BLENDS OF OLIGOPEPTIDE TERMINAL POLYISOBUTYLENE OR POLYSTYRENE
20200347217 ยท 2020-11-05
Inventors
- Emmanuel Croisier (Lausanne, CH)
- Holger Frauenrath (Lausanne, CH)
- Su Liang (Lausanne, CH)
- Veronique Michaud (Lausanne, CH)
Cpc classification
C08L2205/02
CHEMISTRY; METALLURGY
C08L89/00
CHEMISTRY; METALLURGY
C08L2205/025
CHEMISTRY; METALLURGY
C08L23/22
CHEMISTRY; METALLURGY
C08L89/00
CHEMISTRY; METALLURGY
C08L101/00
CHEMISTRY; METALLURGY
C08L101/00
CHEMISTRY; METALLURGY
C08L23/36
CHEMISTRY; METALLURGY
C09D123/36
CHEMISTRY; METALLURGY
International classification
C08L23/36
CHEMISTRY; METALLURGY
C08H1/00
CHEMISTRY; METALLURGY
C08L23/22
CHEMISTRY; METALLURGY
C08L89/00
CHEMISTRY; METALLURGY
C09D123/36
CHEMISTRY; METALLURGY
Abstract
Various blends of polymers are disclosed, comprising oligopeptide functionalised polymers such as polyisobutylene and polystyrene. Mono-functionalised and di-functionalised polymers (each containing 0 to 5 peptide units beyond its terminal amide group) may be blended with each other and/or with non-functionalised polymers to produce blended compositions. Such compositions are of use, for example, in vibrations dampers. Certain blends also exhibit self-healing properties.
Claims
1. A polymer blend, comprising: a first oligopeptide-terminal polymer component selected from the group consisting of: a hydrophobic, flexible polymer having a glass transition temperature below 20 C. and only one monodisperse oligopeptide end group, the monodisperse oligopeptide end group having 1 to 5 amino acid repeating units; and a hydrophobic, flexible polymer having a glass transition temperature below 20 C. and two monodisperse oligopeptide end groups; and at least one additional polymer component selected from the group consisting of: a hydrophobic, flexible polymer that is different from said first oligopeptide-terminal polymer component and that has a glass transition temperature below 20 C. and only one monodisperse oligopeptide end group, the monodisperse oligopeptide end group having 1 to 5 amino acid repeating units; and a hydrophobic, flexible polymer that is different from said first oligopeptide-terminal polymer component and that has a glass transition temperature below 20 C. and two monodisperse oligopeptide end groups.
2. The polymer blend according to claim 1, wherein at least one of said first oligopeptide-terminal polymer component and said at least one additional polymer component comprises repeating units selected from the group consisting of isobutylene, butadiene, siloxane, acrylate, and fluoropolymer units.
3. The polymer blend according to claim 1, wherein at least one of said first oligopeptide-terminal polymer component and said at least one additional polymer component comprises one or more of isobutylene, isoprene or styrene units.
4. The polymer blend according to claim 1, wherein said first oligopeptide-terminal polymer component and said at least one additional polymer component include a hydrophobic, flexible isobutylene polymer having a glass transition temperature below 20 C. and only one monodisperse oligopeptide end group, the monodisperse oligopeptide end group having 1 to 5 amino acid repeating units, blended with a hydrophobic, flexible styrene polymer having a glass transition temperature below 20 C. and only one monodisperse oligopeptide end group, the monodisperse oligopeptide end group having 1 to 5 amino acid repeating units.
5. The polymer blend according to claim 1, wherein an oligopeptide moiety of said first oligopeptide-terminal polymer component comprises L-alanine units.
6. The polymer blend according to claim 1, wherein a polymer segment of at least one of said first oligopeptide-terminal polymer component and said at least one additional polymer component is selected from the group consisting of: polyisobutylene, poly(isobutylene-co-isoprene), polyisoprene, polybutadiene, polysiloxane, polyacrylate, poly(ethylene-co-butylene), hydrogenated poly(isoprene), hydrogenated poly(butadiene), and a fluoropolymer.
7. The polymer blend according to claim 6, wherein said fluoropolymer is poly(tetrafluoroethylene-co-ethylene).
8. The polymer blend according to claim 1, wherein said first oligopeptide-terminal polymer component and said at least one additional polymer component include a hydrophobic, flexible polyisobutylene polymer having one or two monodisperse oligopeptide end groups blended with a hydrophobic, flexible polystyrene polymer having one or two monodisperse oligopeptide end groups.
9. The polymer blend according to claim 1, in the form of a shape-persistent thermoplastic elastomer.
10. The polymer blend according to claim 1, wherein each of said oligopeptide end groups of said first oligopeptide-terminal polymer component and said at least one additional polymer component is the same.
11. The polymer blend according to claim 10, wherein each of said oligopeptide end groups of said first oligopeptide-terminal polymer component and said at least one additional polymer component has the same 2 amino acid repeating units beyond its terminal amide group.
12. The polymer blend according to claim 1, comprising interpenetrating supramolecular polymer networks in which two or more specific supramolecular interactions result in the formation of two or more independent, interpenetrating supramolecular networks with different transition temperatures, that is, deaggregation temperatures.
13. A vibration damping material comprising the polymer blend according to claim 12.
14. The vibration damping material according to claim 13, being a composite material including one or more of the following: a plasticizer; and a reinforcing filler comprising carbon fibre, carbon black, or silica particles.
15. The vibration damping material according to claim 13, in a form adapted to reduce vibration within a vehicle, the form being a pad or other layer which can be interposed between members of the vehicle subject to vibration.
16. A vehicle which includes the vibration damping material according to claim 13.
17. The vehicle according to claim 16, which is a motor vehicle or an aerospace vehicle.
18. A method of vibration damping which involves use of the polymer blend according to claim 1 upon or within a structure or a vehicle.
19. A polymer blend, comprising: at least one hydrophobic, flexible polymer having a glass transition temperature below 20 C. and only one monodisperse oligopeptide end group, the monodisperse oligopeptide end group having 1 to 5 amino acid repeating units; and at least one hydrophobic, flexible polymer having a glass transition temperature below 20 C. and two monodisperse oligopeptide end groups.
20. The polymer blend according to claim 19, wherein said at least one hydrophobic, flexible polymer having only one monodisperse oligopeptide end group and said at least one hydrophobic, flexible polymer having two monodisperse oligopeptide end groups comprise the same type of polymer segment.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] In order that the invention may be further described, more easily appreciated and readily carried into effect by those skilled in the art, reference will now be made to embodiments by way of non-limiting example only and with reference to the accompanying drawings, in which:
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DETAILED DESCRIPTION OF EXAMPLES
[0080] As shown in the drawings and referring in particular to
[0081]
[0082] Differently from all previous examples of supramolecular networks, the aggregation of the oligopeptide-terminated polymers that constitute the basis of the present invention that comprise chiral and monodisperse (molecularly defined) oligopeptides as hydrogen-bonded ligands results in a highly selective formation of small hydrogen-bonded aggregates from compounds with short oligopeptides (such as M0-M1, D0-D1), flexible single -sheet tapes from compounds with medium-size oligopeptides (such as M2-M3, D2-D3), or rigid stacked -sheet fibrils from compounds with longer oligopeptides (such as M4-M5, D4-D5), because the helical conformation of single oligopeptide -strands, the induced helical twisting of -sheets, and finally the number of stacked -sheets are intimately interrelated. This length-dependent self-assembly is even self-sorting, that is, specific in the sense that the different nanostructures obtained from different oligopeptide segments coexist in bulk. It is this particular feature that has enabled us to tailor the thermomechanical properties of the blends. Thus, mixtures of molecules with matching oligopeptide termini (identical oligopeptide length and amino acid sequence) gave rise to thermoplastic elastomers that were inherently reinforced with -sheet tapes or fibrils. By contrast, blends of derivatives with non-matching oligopeptide termini (different oligopeptide length or amino acid sequence, including non-functionalized polymers) formed novel interpenetrating supramolecular networks. It is worth noting that in both cases, network formation allows for dynamic network reorganization processes and may give rise to self-healing or thermoresponsive materials. In this regard, polyisobutylene soft segments have proven to be of high interest, due to their conformational dynamics and resulting macroscopic properties. See in particular the manifold examples. Further examples of blends of non-functionalised and oligopeptide-terminated derivatives of flexible and hydrophobic polymers, such as polyisoprene, polybutadiene, polyacrylates, polysiloxanes, or fluoropolymers, share the same structural features and properties and are embraced by the current invention.
[0083] Referring in particular to
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[0086] Peak deconvolution of the amide I regions of samples of PIB-Ala.sub.n-Ac M0-M5 as well as Ac-Ala.sub.n-PIB-Ala.sub.n-Ac D0-D5 are shown in bulk (see
[0087]
[0088] The monofunctional compounds M0-M5 and the difunctional compounds D0-D5 exhibited distinctly length-dependent aggregation properties. According to IR spectroscopy, M4-M5 and D4-D5 gave rise to highly ordered and strongly aggregated antiparallel -sheet structures both in bulk and in solution. M2-M3 and D2-D3 were only aggregated in bulk materials. The end groups in M0-M1 and D0-D1 were too short to induce -sheet formation either in the bulk or in solution. Atomic force microscopy (AFM) imaging then established a link to the corresponding nanoscopic morphologies for the monofunctional derivatives M0-M5. Thus, rigid and many micrometres long fibrils with diameters of a few nanometres were observed for M5 and M4 on both highly oriented pyrolytic graphite (HOPG) and SiO.sub.2 substrates. The dimensions of fibrils obtained from M5 suggested that they were formed from 4-6 stacked -sheet tapes. In the case of M4, the fibrils were formed from 2-4 stacked -sheet tapes, according to their cross-sections determined by AFM imaging. M3 gave rise to long flexible fibrils or tapes on HOPG that were thinner than those of M4 and exhibited an epitaxial orientation with the substrate. In the case of M2, we observed laterally aggregated tape-like features on HOPG with lengths on the order of a few hundred nanometres. The epitaxial orientation of the tape-like features from M2-M4 on HOPG as well as their absence on SiO.sub.2 substrates suggested that they had not already been present in solution but formed upon drying of the sample on the AFM substrate, in agreement with the IR spectroscopic results. Hence, our results prove that longer oligopeptides did not only result in the expected increase in aggregation strength but that superstructure formation was also affected, due to the molecular chirality of an oligo(L-alanine) segment. We proved that we selectively obtained rigid stacked -sheet fibrils from the longest oligopeptides (n 4 alanine residues); single -sheet tapes from medium-size oligopeptides (n=2-3 alanine residues) in the bulk; and weak, undefined aggregates from short hydrogen-bonded end groups (n=0-1 alanine residues).
[0089] Referring in particular to
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[0092] Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and temperature-dependent solid-state IR spectroscopy proved that M0-M2 and D0-D2 were straightforwardly processable below their degradation temperature of 250 C. Moreover, M2 and D2 exhibited detectable reversible thermal transitions at 170 C. and 178 C., respectively, according to DSC, that solid state IR spectroscopy proved to be associated with -sheet deaggregation.
[0093] Referring in particular to
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[0096] Shear rheology on the monofunctional derivatives M0-M5 in comparison to unmodified polyisobutylenes revealed a transition of mechanical properties from moderately viscous liquid (M0-M1) to a rubbery behaviour (M4-M5) as a function of the number of n alanine residues. Starting with the -sheet tape-forming derivatives M2-M3, the materials exhibited shear moduli exceeding those of high molecular weight polyisobutylenes, although the molecular weight of the attached polymer (MW 1,200) was far below the entanglement length of PIB (15,000) and the monofunctional derivatives cannot form hydrogen-bonded networks. The storage and loss moduli at 1 rad/s within the series leveled off towards G0.6 MPa and G0.06 MPa, indicating that a further increase of the oligopeptide length would not substantially affect the materials' mechanical properties anymore. The network-forming difunctional derivatives D0-D2 showed even more drastic changes in mechanical properties as a function of oligopeptide length, and D2 was already a brittle hard solid (G=2 MPa). While the notion of a mechanical reinforcement is certainly well in line with previous examples of supramolecular networks, the observed drastic dependence of aggregation behaviour and mechanical properties on the number of hydrogen-bonding sites allows for further tailoring of the materials' thermomechanical properties in blends of the investigated compounds. See in particular the disclosed examples.
[0097] Referring in particular to
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[0103] Binary blends of monofunctional and difunctional derivatives with matching oligopeptide segments were found to give rise to supramolecular networks that were inherently reinforced by the incorporated -sheet aggregates. Specifically, binary blends of the thermally processable compounds M2 and D2 with the compositions (by weight) M2/D2 99:1 (Example 1), 95:5 (Example 2), 9:1 (Example 3), 7:3 (Example 4), 5:5 (Example 5), and 1:9 (Example 6) were obtained by dissolving mixtures of the compounds in tetrachlorethane (TCE), stirring the solutions at room temperature for 16 h, removing the solvent in vacuo, and drying the resulting materials in high vacuum at 120 C. for 3 days. Independent of their composition, the blends exhibited solid state IR spectra with amide I regions indistinguishable from the pure compounds and underwent a single-step melting transition at 160-170 C. associated with the deaggregation of all -sheet structures. The blends yielded rubbery materials with shear moduli that exceeded those of even high molecular weight PIB (0.2 MPa) by an order of magnitude even for low fractions of D2. Thus, the storage moduli already reached G=0.6 MPa upon the addition of 5 wt % D2 (Examples 2-6) and leveled off toward G 2 MPa for 10 wt % D2 (Examples 3-6). At the same time, the latter materials (Examples 3-6) experienced a sharp decrease of their moduli and viscosities at their melting temperatures. Hence, we obtained inherently reinforced polyisobutylene-based thermoplastic elastomers that exhibited superior shear properties and showed lower creep behaviour at room temperature, but yielded well-processable melts at elevated temperatures, well below their decomposition temperature.
[0104] Table 1 shows representative values of storage moduli G, loss moduli G, loss factors tan , and viscosities |*| for different grades of polyisobutylenes, M0-M5, D0-D2, as well as Examples 1-6.
[0105] Referring in particular to
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[0114] Binary and ternary blends of compounds with non-matching oligopeptides (different oligopeptide length or amino acid sequence, including non-functionalised polymers) were found to give rise to novel interpenetrating supramolecular networks. Specifically, binary blends (compositions by weight) of M2/D1 1:4 (Example 7), M2/polyisobutylene MW 75'000 (Example 8), M2/polyisobutylene MW 35'000 (Example 9), as well as the ternary blend M2/D2/polyisobutylene (MW 35'000) 4:1:5 (Example 10) were obtained by dissolving mixtures of the compounds in tetrachlorethane (TCE), stirring the solutions at room temperature for 16 h, removing the solvent in vacuo, and drying the resulting materials in high vacuum at 120 C. for 3 days. The annealing temperature was chosen such that it was below the melting transition of the tape-forming component M2 but above the softening temperature of the second network-forming component (D1 or polyisobutylene). In the case of Example 7, the gelation point of M2 and the entanglement point of D1 were superimposed in their blends, resulting in materials with both a gelation and an entanglement point within a similar frequency range (in a classical rheological frequency sweep at 25 C.). Thus the material exhibited a large frequency region with pronounced liquid-like behaviour (that is, G>G) at room temperature, confined by two regions of solid elastomer-like (G>G) behaviour at higher and lower shear frequencies, as seen from a rheological time-temperature superposition (TTS) master curve at 25 C. (all shift factors log a.sub.T and log b.sub.T. for the TTS master curves listed in Table 2). Whilst high molecular weight polyisobutylene materials may exhibit such regions of liquid-like behaviour at temperatures just above their glass transition temperature of T.sub.g65 C., Example 7 showed such behaviour over a large temperature range and a broad frequency range at room temperature, exhibiting a large loss factor of up to tan =2.0 in this region, which is unprecedented in related materials. Upon heating Example 7 above the materials' glass-transition temperature of about T.sub.g=55 C., both its storage and loss moduli as well as viscosity first closely followed those of D1. At about 65 C., where pure D1 is already in its liquid regime, the storage and loss moduli became similar to those of M2 and remained constant up to the melting transition at above 139 C. The pronounced effect of the minority component M2, the two-stage temperature transition, and the superimposed rheological properties of the pure components in the blend provide sufficient evidence for the presence of two independent hydrogen-bonded superstructures, resulting in an interpenetrating supramolecular network. Whereas the high frequency boundary of the liquid-like region can be assigned to the hydrogen-bonded network formed by D1, the low frequency boundary is associated to a percolation network of the M2 -sheet tapes.
[0115] The observed pronounced liquid-like behaviour (in a certain temperature and mechanical frequency range), that is, the apparent molecular level properties approaching liquid-like properties (such as flow) in a solid and macroscopically shape-persistent polymer materials is the prerequisite for the self-healing properties of the materials disclosed here.
[0116] For the various blends of M2, D2, and polyisobutylenes (Examples 8-10), Solution-phase IR spectra in chlorinated solvents showed that all mixtures remained non-aggregated in solution. This enabled us to obtain homogenous blends from solution, so as to obtain hydrogen-bonded aggregates from M2 dispersed in PIB as a matrix material (Examples 8-9) that can be cross-linked using the difunctional network-forming difunctional D2 (Example 10). Solid-state infrared (IR) spectroscopy of the bulk materials revealed strongly aggregated and highly ordered antiparallel -sheet structures. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) proved that the materials were thermally stable (against degradation) up to at least 250 C. All materials exhibited sharp and reversible thermal transitions at temperatures of 169-178 C. Comparing the enthalpies of fusion of pure M2 and D2 (16-17 J/g) to those of the blends (6-6.5 J/g), we concluded that 75-80% of the oligopeptide-modified components were aggregated into -sheet tapes or fibrils in the blends. Moreover, temperature-dependent solid-state IR spectroscopy on the materials proved that the observed transition was associated to -sheet deaggregation in all cases. Visualization of the nanoscopic morphologies of the obtained aggregates by means of atomic force microscopy (AFM) imaging of continuous 1 m thick films drop-cast from TCE solution onto SiO.sub.2 substrates proved that -sheet tape or fibril structures were present in those bulk materials.
[0117] In order to evaluate the mechanical properties of Examples 8-10, we tested their rheological properties in comparison to unmodified higher molecular weight polyisobutylenes (MW 35'000, 75'000, and 200,000). Compared to Smactane, PIB (MW 200'000) showed lower storage (G) and loss moduli (G) over the whole range of frequencies (10.sup.4-10.sup.6 rad/s) or temperatures (45 C.-105 C.) investigated, but a slightly higher and broader peak of the loss factor tan (as a function of frequency), corresponding to its glass transition. Likewise, pure M2 and the blends M2/PIB (Examples 8-9) showed significantly lower storage and loss moduli over a frequency range of 10.sup.4-10.sup.3 rad/s, but significantly higher loss factors of tan 1 for a large frequency range. Examples 8 and 9, for instance, gave rise to a soft rubber-like material with storage and loss moduli G and G that were very similar to one another over almost the complete range of investigated frequencies, as determined from a TTS master curve at room temperature (all shift factors log a.sub.T and log b.sub.T. for the TTS master curves listed in Table 2). As a result, the loss factor of Examples 8 and 9 peaked at tan =1.1 at a reduced frequency of about a.sub.T=510.sup.4 rad/s and never fell below tan =0.6 in the reduced frequency range of a.sub.T=10.sup.3-10.sup.6 rad/s. The ternary blend M2/D2/PIB (MW 35'000) 4:1:5 (Example 10) possesses higher storage and loss moduli as well as similar loss factors compared to Smactane, but with even improved moduli and loss factor at low frequencies, due to the addition of D2 which acts as a network forming crosslinker, resulting in an extra reinforcement of the materials. Moreover, the obtained master curves had a substantially different shape as compared to either pure M2 or unmodified polyisobutylenes. Specifically, the rubbery plateau in the low-frequency regime was absent, indicating that neither does M2 just serve as a filler, nor does the polyisobutylene matrix just act as a diluting solvent. One can therefore attribute the large temperature and frequency range of high loss factor tan values to an interpenetration of the PIB entanglement network and a percolation network formed by the M2 -sheet tapes. The resulting supramolecular networks exhibit an improved vibration damping performance was attributed to improved energy dissipation by the high fraction of pendant polymer chains incorporated into the network.
[0118] Such interpenetrating supramolecular networks as described here provide an alternative to traditional IPNs for the preparation of high-performance vibration damping materials. In order to evaluate the performance of Examples 8-10 with other damping materials, we tested their shear vibration damping characteristics of the in comparison to unmodified higher molecular weight polyisobutylenes (MW 35'000, 75'000, and 200,000), as well as Smactane, a commercially available high performance damping material with excellent damping properties specifically at low temperatures. To this end, we employed a random vibration modal analysis test on a sandwich structure representing a typical constrained damping layer application. The test structure was designed specifically to investigate the structural damping performance of the material in low frequency vibration (30-40 Hz), which is typical for the first vibration modes of many steel or aluminium panels used in automotive or aerospace applications. The specimen with a free length of 54 mm was fixed at one end while a weight of 4.6 g was clipped to the other one. The beam was excited using a pseudo random signal using a vibration shaker driven through an open loop random vibration controller. Accelerometers were used to monitor the base and tip accelerations and reconstruct the frequency response function of the system around its first resonance peak. The modal damping ratio was obtained by single-degree-of-freedom modal curve fitting of the resonance peak in the complex domain.
[0119] All results of the damping tests and derived damping ratios are listed in Table 3.
[0120] The first resonance frequency for steel, in this particular set up, occurred at 32 Hz and was slightly damped by steel itself and its clamping on the base (0.4%). However, damping ratio significantly increased to 2.9% once Smactane was used as the damping layer in the sandwich structure. By comparison, while unmodified high molecular weight PIB (MW 200'000) exhibited a low damping ratio of 1.4%, the damping ratios were 3.2% for pure M2, 2.6% for the binary blend M2/PIB (MW 75'000) (Example 8), 2.5% for the binary blend M2/PIB (MW 35'000) (Example 9), and 3.4% for the ternary blend M2/D2/PIB (MW 35'000) (Example 10). Examples 9 and 10 thus showed excellent damping ratios, even exceeding those of the commercially available high-performance damping material Smactane and by far surpassing those of unmodified PIB that is considered to possess good damping properties and is already used in damping applications on a technological scale.
[0121] Moreover, we complemented our results with detailed finite element (FE) simulations of the sandwich beam vibration tests. We performed the simulations also on other high-performance damping materials as a reference, including Smactane, Soundcoat Dyad 601 and 3M ISD 130.54 using their rheology data as the input to the FE simulations. In qualitative agreement with the experimental results, the finite element simulations resulted in damping ratios of Examples 8-10 above those of the reference materials.
[0122] The damping properties of the investigated materials at low temperatures were obtained using the loss moduli G obtained from rheological frequency sweep experiments at those temperatures and calculating the dissipated energies during one cycle of oscillatory stress-strain test from the area of the corresponding Lissajous curves (corrected for the imposed strain).
[0123] The calculated damping properties at low temperatures are listed in Table 4.
[0124] All of the investigated materials and, in particular, the ternary blend M2/D2/PIB (MW 35'0000) (Example 10) exhibit excellent damping properties at temperatures of 45 C. and below, down to their glass transition temperatures at about T.sub.g65 C., even exceeding those of Smactane and in marked contrast to PIB (MW 200,000) that possesses lower loss moduli over the whole range of frequencies (0.1-100 rad/s) tested at 45 C.
[0125] All commercial reference materials (except PIB) are composites with formulations highly optimized for damping performance. It is worth noting that, as a consequence, our materials were light (with a density of 0.92 g/cm.sup.3 compared to 1.18 g/cm.sup.3 for Smactane) and did not require any additional fillers or low molecular weight plasticizers. Moreover, as the ideal damping characteristics depend on the application, the versatility offered by the use of oligopeptide-modified polymers as additives to commercial elastomers appears to provide an excellent pathway towards lightweight, low-creep, and high-performance constrained layers for vibro-acoustic damping.
[0126] Referring in particular to
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2. PREPARATIVE EXAMPLES
2.1 Instrumentation and Methods
[0130] NMR Spectroscopy was carried out on a Bruker Avance 300 spectrometer operating at a frequency of 300.23 MHz for .sup.1H and 75.49 MHz for .sup.13C nuclei, or on a Bruker Avance 400 spectrometer operating at a frequency of 400.23 MHz for .sup.1H and 100.63 MHz for .sup.13C nuclei. Deuterated solvents were purchased from Cambridge Isotope Laboratories. The spectra were calibrated to the respective residual proton peaks of the deuterated solvents (.sup.1H NMR: 7.26 ppm CDCl.sub.3, 6.0 ppm TCE-d.sub.2, 5.32 ppm, DMSO-D.sub.6, 3.31 ppm CD.sub.3OD; .sup.13C NMR: 77.16 ppm CDCl.sub.3, 49.00 ppm CD.sub.3OD, 39.52 ppm DMSO-D.sub.6).
[0131] SolutionPhase FTIR Spectra were recorded on a Spectrum One IR spectrometer from Perkin Elmer using a solution-phase cuvette with KBr windows and a light path of 0.5 mm, or on a Jasco FT/IR-6300 Fourier, using a KBr window 323 mm (by Pike Technology). The materials were dissolved in either TCE or CHCl.sub.3 (5 mg/mL). The TCE solutions were stirred for 1 h at 100 C. and left to slowly cool to room temperature. The CHCl.sub.3 solutions were stirred at RT for 1-16 h.
[0132] Solid-State FTIR Spectra were recorded on a Bruker ALPHA FTIR spectrometer or on a JASCO FT/IR 6300 spectrometer using the Miracle ATR accessory from PIKE, as well as on a Varian Fourier Transform spectrometer equipped with a Golden Gate diamond ATR with temperature control up to 200 C.
[0133] High Resolution Mass Spectra were recorded at the Mass Spectrometry Service of EPFL on either an AXIMA Performance device from Shimadzu Biotech for MALDI-TOF and a Q-TOF Ultima from Waters for ESI-TOF, or at the Mass Spectrometry Service of ETH Zurich on a Bruker Daltonics maXis for HiRes-ESI-MS.
[0134] Thermogravimetric Analyses were performed on a TGA Q500 device from TA Instruments, loaded with samples of more than 2 mg. The measurement range was 50-710 C. in a nitrogen atmosphere or 50-914 C. in air. A heating rate of 10 C./min was applied in all cases.
[0135] Differential Scanning calorimetry was performed on a DSC Q1000 from TA Instruments in a nitrogen atmosphere, loaded with samples of more than 2 mg. For the measurement of glass transition or melting temperatures, three measurements were performed in the range of 80 to 400 C. Both the heating and cooling rates were 10 C./min. All data were collected from the second heating cycle.
[0136] Combustion Elemental Analyses were carried out as service measurements at EPFL using EA 1100 CHN Instrument or at the Institute of Organic Chemistry at ETH Zurich using a LECO CHN/900 instrument.
[0137] AFM Imaging was performed on a Nanoscope IIIa instrument. Samples were prepared from stock solutions of the compounds in tetrachlorethane (TCE) at an initial concentration c=10.sup.3 mol/L. The solutions were placed into sealed tubes, vigorously stirred (400 rpm) and heated in an oil bath to 180 C. for 2 h, followed by stepwise cooling 160 C. (1 h), 140 C. (1 h), 120 C. (1 h), and 100 C. (1 h) under continued stirring (100 rpm). Afterwards, the heating was switched off and the solution was allowed to cool to room temperature at the same stirring rate. The solutions were then diluted to a concentration of c=110.sup.4 mol/L or c=510.sup.5 mol/L and spin-coated onto SiO.sub.2 substrates treated with ethanol and ultrapure water (3000 rpm) or onto freshly cleaved HOPG (1800 rpm). The obtained samples were analyzed in tapping mode at room temperature in air, using cantilevers with an average resonance frequency of 75 kHz and scan rates of 0.5-1.5 Hz. The image resolution was 512512 pixels.
[0138] Dynamic Shear Rheology Measurements were carried out on parallel plate rheometers AR 2000, ARES LR2 or ARES from TA Instruments. Disc shaped sample specimen from all materials that were shape-persistent were prepared on a Rittal table press. A force of 2 kN was applied for 30 min at 100 C., after which the specimen were cooled to 20 C. at a force of 1.1 kN for 30 min. Depending on the samples quantity, aluminium plates of 15 mm or 25 mm diameter, as well as stainless steel plates of 25 mm diameter were used. Discs of 12 mm diameter were prepared as well and placed in the centre of the stainless-steel plates (25 mm diameter) with a centring tool. The gap between the plates was in the range of 0.4-2 mm. In the case of non-adhesive samples, the plates were covered with emery paper to avoid wall slipping. Measurements were carried out at temperatures of 45 C. to 250 C. Once the desired temperature was reached, the system was equilibrated for 2 min. Frequency sweeps ranging from 100 rad s.sup.1 to 0.01 rad s.sup.1 were carried out under controlled strain. Depending on the sample composition and temperature, the strain amplitude ranged from 0.03% to 50%. The applied strain was defined such that the sample stayed in its linear viscoelastic domain during the complete frequency sweep.
[0139] Modal Damping Tests were carried out on a RMS 3000 vibration shaker using an HP 35670A vibration controller and signal analyzer in open loop pseudo random vibration analysis. The acceleration of the base and of the tip of the specimen were monitored using two Bruel&Kaer 4517 accelerometer through a B&K Nexus 2692 amplifier. The frequency transfer functions of the different specimens were measured in a frequency range of 10 to 110 Hz with a resolution of 0.125 Hz. The test specimen consisted of a sandwich structure representing a constrained damping layer application. The base substrate was a steel plate with dimensions of 6060.5 mm onto which a damping layer with dimensions of 400.62.2 mm was superimposed. A thin steel plate with dimensions of 400.60.2 mm was used to constrain the top of the damping layer. The sandwich test structure was then clamped with one end to the vibration table over a length of 6 mm, and a mass of 4.6 g was added to the free end of the beam over a length of 5 mm. The added mass has been calculated such that the first bending mode of the sandwich beam is in the range of 30-40 Hz. In order to determine the modal damping ratio the first peak of the frequency response function was first fitted using a complex polynomial fraction least square method integrated in the HP 35670A signal analyzer. The modal damping ratio was then calculated from the real part X and the imaginary part of the first complex pole of the polynomial fraction using the definition =/.
[0140] Finite Element Simulations of the sandwich beam vibration tests have been carried out to compare the damping performance of M2/PIB with other high-performance damping materials in this particular application. The chosen specimen geometry was the same as the sandwich beam specimen used in the experimental modal damping tests (6060.5 mm steel base plate with a 400.62.2 mm damping layer constrained on top by a 400.60.2 mm steel sheet). The base plate was modelled as being clamped to the shaker on one side (imposed displacement, no rotation, over 6 mm) and attached to two steel blocks of 5515 mm. The steel plates were modelled as linear elastic with a Young modulus of 210 GPa, Poisson ratio of 0.3 and mass density of 7,800 kg/m.sup.3. The damping layer materials were all considered incompressible and modelled using an Arruda-Boyce hyperelastic potential (power exponent of 7) with complex shear moduli taken from rheology measurements or literature data (Table 3). The whole specimen was modelled using 2640 3D hybrid quadratic hexahedric elements (14345 nodes) in Simulia Abaqus 6.10 (
2.2 Materials and General Synthesis Procedures
Materials.
[0141] Reagents were purchased as reagent grade from commercial sources and used without further purification. Poly(isobutylene) 1 (Kerocom PIBA) was obtained from BASF and purified from non-functionalized poly(isobutylene) by column chromatography prior to use. Poly(isobutylene) diamine 4 containing about 10% of monofunctional poly(isobutylene) amine was obtained from BASF SE, Germany, and used without further purification. THF, acetonitrile, toluene, dichloromethane and triethylamine were purchased as HPLC grade and dried using a solvent purification system from Innovative technologies. Other solvents were purchased as reagent grade and distilled once prior to use. Thin Layer Chromatography (TLC) Analyses were performed on TLC plates from Merck; UV-light (254 nm) or standard colouring reagents were used for detection. Column Chromatography was conducted on Geduran Silica gel Si 60 from Merck (40-60 m).
[0142] Sample Preparation. For the preparation of films and solid samples of either single compounds or blends, the oligopeptide-polymer derivatives and/or PIB (MW 75,000) were dissolved in either TCE or CHCl.sub.3, the solutions were stirred at room temperature for 1-16 h, and concentrated in vacuo. The resulting materials were dried in HV at 120 C. for 3 days.
[0143] General Procedure A: Peptide Coupling. The carboxylic acid derivative was dissolved in THF. The amine (1 equiv) was added, as well as N-ethyldiisopropylamine (DIEA; 3 equiv) and (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (PyBOP; 1.2 equiv). The solution was stirred for 3-16 h, and the reaction progress was monitored by TLC. The crude product was typically purified by precipitation into water (see General Procedures C or D). Specific purification or sample preparation procedures were performed before further characterization in some cases.
[0144] General Procedure B: Fmoc Deprotection. The Fmoc-protected amine derivatives were dissolved in CHCl.sub.3. Then, a large excess of piperidine (15 equiv) was added, and the solution was stirred overnight. The reaction progress was monitored by TLC. After completion of the reaction, the solvents were removed in vacuo. Unless otherwise noted, the crude product was purified by column chromatography.
[0145] General Procedure C: Precipitation of Compounds Soluble in THF. After completion of the reaction affording the desired compound, the reaction mixture was concentrated to half of its original volume. A large excess of aqueous 1 M HCl solution was added. The resulting precipitate was filtered off, re-dissolved in THF and precipitated again, following the same procedure as described above. After three repetitive precipitations, the crude product was finally dissolved in CH.sub.2Cl.sub.2, CHCl.sub.3 or THF. The solution was dried over MgSO.sub.4 and concentrated in vacuo at 40 C.
[0146] General Procedure D: Precipitation of Compounds Insoluble in THF. After completion of the reaction affording the desired compound, the reaction mixture was diluted with a large excess of aqueous 1 M HCl solution. The precipitate was collected and re-dispersed in THF at 60 C. The product was precipitated again using the same procedure as described above two more times. The precipitate was finally re-dispersed in THF and concentrated in vacuo at 40 C.
2.3 Synthesis Procedures and Analytical Data for 2-3, 5-6, M0-M5 and D0-D5
[0147] Synthesis of PIB.sub.19-Ala.sub.3-Fmoc 2. Following General Procedure A, PIB.sub.19-NH.sub.2 1 (14.55 g, 12.03 mmol) and N-(9-fluorenylmethyloxycarbonyl)-L-alanyl-L-alanyl-L-alanine (6.0 g, 13.23 mmol) were dissolved in THF (250 mL). DIEA (6.18 mL, 36.08 mmol) and PyBOP (7.51 g, 14.43 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (19.2 g, 97%) was obtained as a slightly yellow wax. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.75 (d, J=7.5 Hz, 2H, aromatic H), 7.57 (d, J=7.5 Hz, 2H, aromatic H), 7.52 (m, 1H, NH), 7.38 (d, J=7.4 Hz, 2H, aromatic H), 7.29 (t, J=7.4 Hz, 2H, aromatic H), 7.13 (m, 1H, NH), 6.76 (m, 1H, NH), 5.84 (m, 1H, NH), 4.73-4.29 (m, 5H, Fmoc-CO.sub.2CH.sub.2, 3 CHCH.sub.3), 4.20 (t, J=7.0 Hz, 2H, fluorenyl CH), 3.31-3.07 (m, 2H, CH.sub.2NH), 1.81-0.53 (m, 178H, aliphatic H, 3 CHCH.sub.3). MS (MALDI-TOF, DCTB/NaTFA 10:1): calcd for C.sub.73H.sub.126N.sub.4O.sub.5Na: (n=10[M+Na]+) 1161.9620; found: 1161.8517. R.sub.f: 0.45 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=66 C.
[0148] Synthesis of PIB.sub.19-Ala.sub.3-H 3. Following General Procedure B, PIB.sub.19-Ala.sub.3-Fmoc 2 (17.2 g, 10.46 mmol) was dissolved in CHCl.sub.3 (250 mL). Piperidine (10.35 ml, 104.57 mmol) was added, and the reaction mixture was stirred at room temperature overnight. The crude product was purified by column chromatography (silica gel, gradient CH.sub.2Cl.sub.2.fwdarw.CH.sub.2Cl.sub.2/MeOH 5:1). The final product (10 g, 67%) was obtained as a slightly yellow wax. 1H NMR (400 MHz, CDCl.sub.3) =7.83 (d, J=7.3 Hz, 1H, NH), 7.10 (m, 1H, NH), 6.46 (m, 1H, NH), 4.45 (m, 2H, CHCH.sub.3), 3.51 (q, J=6.9 Hz, 1H, CHCH.sub.3NH.sub.2), 3.4-3.1 (m, 2H, CH.sub.2NH), 1.82-0.65 (m, 178H, aliphatic H, 3 CHCH.sub.3). MS (MALDI-TOF, DHB): calcd for C.sub.58H.sub.116N.sub.4O.sub.3Na: (n=10 [M+Na].sup.+) 939.8940; found: 940.0981. R.sub.f: 0.15 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=68 C.
[0149] Synthesis of Fmoc-Ala.sub.3-PIB.sub.40-Ala.sub.3-Fmoc 5. Following General Procedure A, N-(9-fluorenylmethyloxycarbonyl)-L-alanyl-L-alanyl-L-alanine (4.36 g, 9.61 mmol) and NH.sub.2-PIB.sub.40-NH.sub.2 4 (10.9 g, 4.28 mmol) were dissolved in THF (400 mL). DIEA (2.47 mL, 14.42 mmol) and PyBOP (5.50 g, 10.58 mmol) were added. After 16 h, the crude product was precipitated following General Procedure D. The final product (14.18 g, 94%) was obtained as a white solid. .sup.1H NMR (400 MHz, C.sub.2D.sub.2Cl.sub.4 at 110 C.) =7.81 (d, J=7.5 Hz, 4H, aromatic H), 7.63 (d, J=7.3 Hz, 4H, aromatic H), 7.50-7.41 (m, 5H, aromatic H), 7.4-7.3 (m, 4H, aromatic H), 7.21 (m, 3H, aromatic H), 6.52 (m, 2H, NH), 6.34 (m, 2H, NH), 6.00 (m, 2H, NH), 5.16 (m, 2H, NH), 4.63-4.08 (m, 12H, 6 CHCH.sub.3, 2 Fmoc-CO.sub.2CH.sub.2, 2 fluorenyl CH), 3.37-2.94 (m, 4H, 2CH.sub.2NH), 1.94 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.62-0.98 (m, 346H, aliphatic H, 6 CHCH.sub.3), 0.95 (s, 12H, 2PhC(CH.sub.3)2). MS (MALDI-TOF, DCTB): calcd for C.sub.104H.sub.158N.sub.8O.sub.10Na: (n+m=9 [M+Na].sup.+) 1702.1993; found: 1702.3004. R.sub.f: 0.4 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=55 C.
[0150] Synthesis of H-Ala.sub.3-PIB.sub.40-Ala.sub.3-H 6. Following General Procedure B, Fmoc-Ala.sub.3-PIB.sub.40-Ala.sub.3-Fmoc 5 (11.00 g, 3.2 mmol) was dissolved in CHCl.sub.3 (200 mL). Piperidine (200 ml, 2.02 mol) was added, and the reaction mixture was stirred at room temperature overnight. The next day, the solvent was evaporated in vacuo, and the mixture was washed three times with cold heptane. The crude product was then dispersed in DCM and concentrated in vacuo at 40 C. Finally, the product (7.76 g, 82%) was obtained as a white solid. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.96 (m, 2H, NH), 7.71 (m, 6H, NH2+TFA), 7.47 (m, 2H, NH), 7.38 (m, 1H, aromatic H), 7.21-7.06 (m, 3H, aromatic H), 6.88 (m, 2H, NH), 4.7-4.2 (m, 4H, CHCH.sub.3), 3.41-2.79 (m, 6H, 2 CH.sub.2NH, 1 CH.sub.2NH.sub.2), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.77-0.87 (m, 346H, aliphatic H, 6CHCH.sub.3), 0.80 (s, 12H, 2 PhC(CH.sub.3).sub.2). MS (MALDI-TOF, DHB): calcd for C.sub.82H.sub.155N.sub.8O.sub.6: (n+m=11 [M+H].sup.+) 1348.2065; found: 1348.5963. R.sub.f: 0.05 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=65 C.
[0151] Synthesis of PIB.sub.19-Ac M0. PIB.sub.19NH.sub.2 1 (3.85 g, 3.18 mmol) was dissolved in THF (80 mL). Acetyl chloride (0.454 mL, 6.37 mmol) and pyridine (0.642 mL, 7.96 mmol) were added. The reaction mixture was stirred overnight. The crude product was precipitated following General Procedure C. The final product (3.53 g, 88%) was obtained as a slightly yellow viscous oil. .sup.1H NMR (400 MHz, CDCl.sub.3) =5.36 (m, 1H, NH), 3.47-3.08 (m, 2H, CH.sub.2NH), 1.96 (s, 3H, COCH.sub.3), 1.73-0.60 (m, 169H, aliphatic H). MS (MALDI-TOF, DCTB/NaTFA 10:1): calcd for C.sub.51H.sub.103NONa (n=10 [M+Na].sup.+) 768.7932; found 768.9546. R.sub.f: 0.85 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=67 C.
[0152] Synthesis of PIB.sub.19-Ala-Ac M1. Following General Procedure A, PIB.sub.19-NH.sub.2 1 (3.69 g, 3.05 mmol) and N-acetyl-L-alanine (0.4 g, 3.05 mmol) were dissolved in THF (100 mL). DIEA (1.57 mL, 9.15 mmol) and PyBOP (1.9 g, 3.66 mmol) were added.
[0153] The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (3.9 g, 97%) was obtained as a slightly yellow viscous oil. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.91 (d, J=7.6 Hz, 1H, NH), 6.87 (m, 1H, NH), 4.75-4.36 (m, 1H, CHCH.sub.3), 3.30 (m, 2H, CH.sub.2NH), 2.16 (s, 3H, COCH.sub.3), 1.64-0.84 (m, 172H, aliphatic H, 1 CHCH.sub.3). MS (MALDI-TOF, DCTB/NaTFA 10:1): calcd for C.sub.54H.sub.108N.sub.2O.sub.2Na: (n=10 [M+Na].sup.+) 839.8303; found: 839.6927. R.sub.f: 0.55 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=65 C.
[0154] Synthesis of PIB.sub.19-Ala2-Ac M2. Following General Procedure A, PIB.sub.19NH.sub.2 1 (17.48 g, 14.46 mmol) and N-acetyl-L-alanyl-L-alanine (3.8 g, 18.79 mmol) were dissolved in THF (250 mL). DIEA (4.95 mL, 28.91 mmol) and PyBOP (9.03 g, 17.35 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (19.5 g, 97%) was obtained as a slightly yellow wax. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.44 (m, 1H, NH), 7.00 (m, 1H, NH), 6.74 (m, 1H, NH), 4.70 (m, 1H, CHCH.sub.3), 4.59 (m, 1H, CHCH.sub.3), 3.45-3.09 (m, 2H, CH.sub.2NH), 2.05 (s, 3H, COCH.sub.3), 1.62-0.64 (m, 175H, aliphatic H, 2 CHCH.sub.3). MS (MALDI-TOF, CHCA/NaTFA 1:1): calcd for C.sub.57H.sub.113N.sub.3O.sub.3Na: (n=10 [M+Na].sup.+) 910.8674; found: 910.7816. R.sub.f: 0.4 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=68 C., T.sub.m=170 C.
[0155] Synthesis of PIB.sub.19-Ala.sub.3-Ac M3. PIB.sub.19-Ala.sub.3-H 3 (2.99 g, 2.1 mmol) was dissolved in THF (150 mL). Acetyl chloride (0.3 mL, 4.2 mmol) and pyridine (0.424 mL, 5.25 mmol) were added and the reaction mixture was stirred overnight. The next day, the product was precipitated following General Procedure C. The final product (3.0 g, 98%) was obtained as a slightly yellow wax. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.58 (m, 2H, NH), 7.13 (m, 1H, NH), 6.90 (m, 1H, NH), 4.66-4.55 (m, 3H, CHCH.sub.3), 3.26 (m, 2H, CH.sub.2NH), 2.11 (s, 3H, COCH.sub.3), 1.70-0.57 (m, 178H, aliphatic H, 3 CHCH.sub.3). MS (MALDI-TOF, CHCA/NaTFA 1:1): calcd for C.sub.60H.sub.118N.sub.4O.sub.4Na: (n=10 [M+Na].sup.+) 981.9045; found: 981.8898. R.sub.f: 0.25 (CH2Cl2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=67 C.
[0156] Synthesis of PIB.sub.19-Ala.sub.4-Ac M4. Following General Procedure A, PIB.sub.19-Ala.sub.3-H 3 (2.0 g, 1.41 mmol) and N-acetyl-L-alanine (184.36 mg, 1.41 mmol) were dissolved in THF (200 mL). DIEA (0.722 mL, 4.22 mmol) and PyBOP (877.98 mg, 1.69 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (2.0 g, 90%) was obtained as a white rubber. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.83 (d, J=7.4 Hz, 1H, NH), 7.60 (m, 1H, NH), 7.34 (d, J=6.1 Hz, 1H, NH), 7.27 (m, 1H, NH), 6.80 (m, 1H, NH), 4.89-4.22 (m, 4H, CHCH.sub.3), 3.45-3.09 (m, 2H, CH.sub.2NH), 2.14 (s, 3H, COCH.sub.3), 1.65-0.74 (m, 181H, aliphatic H, 4 CHCH.sub.3). MS (MALDI-TOF, CHCA/NaTFA 1:1): calcd for C.sub.63H.sub.123N.sub.5O.sub.5Na: (n=10 [M+Na].sup.+) 1052.9416; found: 1052.8131. R.sub.f: 0.1 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=66 C.
[0157] Synthesis of PIB.sub.19-Ala.sub.5-Ac M5. Following General Procedure A, PIB.sub.19-Ala.sub.3-H 3 (2.0 g, 1.41 mmol) and N-acetyl-L-alanyl-L-alanine (284.29 mg, 1.41 mmol) were dissolved in THF (200 mL). DIEA (0.722 mL, 4.22 mmol) and PyBOP (877.98 mg, 1.69 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (2.2 g, 95%) was obtained as a white rubber. .sup.1H NMR (400 MHz, C.sub.2D.sub.2Cl.sub.4 and TFA at 65 C.) =7.44 (d, J=6.9 Hz, 1H, NH), 7.16 (m, 3H, NH), 6.81 (m, 1H, NH), 6.56 (m, 1H, NH), 4.67-4.42 (m, 5H, CHCH.sub.3), 3.45-3.09 (m, 2H, CH.sub.2NH), 2.17 (s, 3H, COCH.sub.3), 1.84-0.68 (m, 184H, aliphatic H, 5 CHCH.sub.3). MS (MALDI-TOF, CHCA): calcd for C.sub.66H.sub.128N.sub.6O.sub.6Na: (n=10 [M+Na].sup.+) 1123.9788; found: 1124.3684. R.sub.f: 0.05 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=69 C.
[0158] Synthesis of Ac-PIB.sub.40-Ac D0. NH.sub.2-PIB.sub.40-NH.sub.2 4 (5.00 g, 1.96 mmol) was dissolved in THF (200 mL). Acetyl chloride (0.80 mL, 11.22 mmol) and pyridine (0.9 mL, 11.22 mmol) were added, and the solution was stirred overnight. The next day, the crude product was precipitated following General Procedure C. The final product (4.4 g, 85%) was obtained as a colourless viscous oil. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.37 (m, 1H, aromatic H), 7.23-7.06 (m, 3H, aromatic H), 5.44 (m, 2H, NH), 3.2-2.9 (m, 4H, 2 CH.sub.2NH), 1.98 (s, 6H, COCH.sub.3), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.75-0.86 (m, 328H, aliphatic H), 0.80 (s, 12H, 2 PhC(CH.sub.3).sub.2). MS (MALDI-TOF, DCTB): calcd for C.sub.76H.sub.144N.sub.2O.sub.2Na: (n+m=13 [M+Na].sup.+) 1140.1120; found: 1139.5068. R.sub.f: 0.7 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=55 C.
[0159] Synthesis of Ac-Ala-PIB.sub.40-Ala-Ac D1. Following General Procedure A, N-acetyl-L-alanine (810.0 mg, 6.17 mmol) and NH.sub.2-PIB.sub.40-NH.sub.2 4 (7.00 g, 2.75 mmol) were dissolved in THF (200 mL). DIEA (1.58 mL, 9.26 mmol) and PyBOP (3.53 g, 6.79 mmol) were added. After 16 h, the crude product was precipitated following General Procedure C. The final product (5.12 g, 66%) was obtained as a yellow glue. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.37 (m, 1H, aromatic H), 7.23-7.06 (m, 3H, aromatic H), 6.17 (m, 4H, NH), 4.45 (m, 2H, CHCH.sub.3), 3.25-2.9 (m, 4H, 2 CH.sub.2NH), 2.00 (s, 6H, COCH.sub.3), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.76-0.85 (m, 334H, aliphatic H, 2 CHCH.sub.3), 0.80 (s, 12H, 2 PhC(CH.sub.3).sub.2). MS (MALDI-TOF, DCTB): calcd for C.sub.86H.sub.162N.sub.4O.sub.4Na: (n+m=14 [M+Na].sup.+) 1338.2488; found: 1338.2838. R.sub.f: 0.5 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=54 C.
[0160] Synthesis of Ac-Ala.sub.2-PIB.sub.40-Ala.sub.2-Ac D2. Following General Procedure A, N-acetyl-L-alanyl-L-alanine (700.0 mg, 3.46 mmol) and NH.sub.2-PIB.sub.40NH.sub.2 4 (3.93 g, 1.54 mmol) were dissolved in THF (300 mL). DIEA (0.89 mL, 5.19 mmol) and PyBOP (1.98 g, 3.81 mmol) were added, and the reaction mixture was stirred overnight. The next day, the crude product was precipitated following General Procedure D. The final product (4.0 g, 89%) was obtained as an off-white solid. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.64-7.3 (m, 6H, NH), 7.37 (m, 1H, aromatic H), 7.23-7.06 (m, 3H, aromatic H), 4.7-4.5 (m, 4H, CHCH.sub.3), 3.25-2.9 (m, 4H, 2 CH.sub.2NH), 2.07 (s, 6H, COCH.sub.3), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.77-0.86 (m, 300H, aliphatic H, 4 CHCH.sub.3), 0.80 (s, 12H, 2 PhC(CH.sub.3).sub.2). MS (MALDI-TOF, DCTB): calcd for C.sub.92H.sub.172N.sub.6O.sub.6Na: (n+m=14 [M+Na].sup.+) 1480.3231; found: 1480.6152. R.sub.f: 0.4 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=57 C., T.sub.m=178 C.
[0161] Synthesis of Ac-Ala.sub.3-PIB.sub.40-Ala.sub.3-Ac D3. H-Ala.sub.3-PIB.sub.40-Ala.sub.3-H 6 (1.50 g, 0.50 mmol) was dissolved in THF (200 mL). Acetyl chloride (0.16 mL, 2.23 mmol) and pyridine (0.18 mL, 2.23 mmol) were added, and the reaction mixture was stirred overnight. The next day, the crude product was precipitated General Procedure D. The final product (1.43 g, 92%) was obtained as an off-white solid. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =8.17.5 (m, 5H, NH), 7.38 (m, 2H, aromatic H, NH), 7.21-7.06 (m, 3H, aromatic H), 6.83 (m, 2H, NH), 4.7-4.3 (m, 6H, CHCH.sub.3), 3.35-2.95 (m, 4H, 2 CH.sub.2NH), 2.12 (s, 6H, COCH.sub.3), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.77-0.86 (m, 346H, aliphatic H, 6 CHCH.sub.3), 0.80 (s, 12H, 2 PhC(CH.sub.3).sub.2). MS (ESI-TOF): calcd for C.sub.74H.sub.135N.sub.8O.sub.8Na: (n=8 [M+H+Na].sup.2+) 643.5145; found: 646.5165. R.sub.f: 0.3 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=55 C.
[0162] Synthesis of Ac-Ala.sub.4-PIB.sub.40-Ala.sub.4-Ac D4. Following General Procedure A, N-acetyl-L-alanine (146.0 mg, 1.11 mmol) and H-Ala.sub.3-PIB.sub.40-Ala.sub.3-H 6 (1.50 g, 0.50 mmol) were dissolved in THF (200 mL). DIEA (215.83 mL, 1.67 mmol) and PyBOP (637.3 mg, 1.22 mmol) were added. After 16 h, the crude product was precipitated following General Procedure D. The final product (1.49 g, 91%) was obtained as an off-white solid. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =8.1-7.5 (m, 6H, NH), 7.38 (m, 2H, aromatic H, NH), 7.21-7.06 (m, 4H, 3 aromatic H, NH), 6.83 (m, 2H, NH), 4.7-4.35 (m, 8H, CHCH.sub.3), 3.35-2.95 (m, 4H, 2 CH.sub.2NH), 2.12 (s, 6H, COCH.sub.3), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.77-0.86 (m, 352H, aliphatic H, 8 CHCH.sub.3), 0.80 (s, 12H, 2 PhC(CH.sub.3).sub.2). MS (ESI-TOF): calcd for C.sub.92H.sub.170N.sub.10O.sub.10: (n+m=11 [M+2H].sup.2+) 787.6545; found: 787.1820. R.sub.f: 0.3 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N2) T.sub.g=55 C.
[0163] Synthesis of Ac-Ala.sub.5-PIB.sub.40-Ala.sub.5-Ac D5. Following General Procedure A, N-acetyl-L-alanyl-L-alanine (195.1 mg, 0.96 mmol) and H-Ala.sub.3-PIB.sub.40-Ala.sub.3-H 6 (1.30 g, 0.43 mmol) were dissolved in THF (200 mL). DIEA (0.25 mL, 1.45 mmol) and PyBOP (552.3 mg, 1.06 mmol) were added. After 16 h, the crude product was precipitated following General Procedure D. The final product (1.30 g, 88%) was obtained as off-white solid. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =8.1-7.5 (m, 10H, NH), 7.38 (m, 2H, aromatic H, NH), 7.21-7.06 (m, 3H, aromatic H), 6.85 (m, 1H, NH), 4.7-4.2 (m, 10H, CHCH.sub.3), 3.35-2.95 (m, 4H, 2 CH.sub.2NH), 2.12 (s, 6H, COCH.sub.3), 1.84 (s, 4H, 2CH.sub.2C(CH.sub.3).sub.2Ph), 1.77-0.86 (m, 358H, aliphatic H, 10 CHCH.sub.3), 0.80 (s, 12H, 2PhC(CH.sub.3).sub.2). MS (ESI-TOF): calcd for C.sub.98H.sub.178N.sub.12O.sub.12Na: (n+m=11 [M+Na].sup.+) 1739.3613; found: 1740.5134. R.sub.f: 0.25 (CH.sub.2Cl.sub.2/MeOH 10:1). DSC (10 C./min, N.sub.2) T.sub.g=54 C.
[0164] Synthesis of PS.sub.15-NH.sub.2 7. Styrene (12.19 g, 117.1 mmol) was freshly distilled from CaH.sub.2 prior to use. A rigorously dried 250 mL Schlenk flask was filled with dry cyclohexane (50 mL), and sec-butyl lithium (5.6 mL, 7.8 mmol, 1.4 M solution in cyclohexane) was added slowly via a syringe at 10 C. Under vigorous stirring, styrene was added via a syringe as fast as possible, leading to a yellow to orange color of the solution. The cooling bath was removed and the mixture was stirred for 1 h. Then, 2.5 excess of 1--bromopropyl)-2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentane (5.47 g, 19.5 mmol) dissolved in dry THF (20 mL) was added via a syringe, causing an immediate decoloration. The mixture was stirred for 2 h at room temperature, then was concentrated in vacuo and taken up in THF (100 mL). Then, 1M HCl (35 mL) was added, and stirring was continued overnight. The mixture was concentrated in vacuo, taken up in CH.sub.2Cl.sub.2, washed twice with 1M KOH and once with sat. NaCl solution. The combined organic phases were dried over MgSO.sub.4, filtered, and concentrated in vacuo. The crude product was purified by column chromatography (silica gel, gradient CH.sub.2Cl.sub.2.fwdarw.CH.sub.2Cl.sub.2/MeOH 20:1). The amine terminated polystyrene (9.2 g, 70%) was obtained as a white solid. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.25-6.3 (m, 75H, Ph-H), 2.48 (m, 2H, CH.sub.2NH.sub.2), 2.36-0.5 (m, 58H, 15 CH.sub.2CHPh, 3 CH.sub.2, 1 CHCH.sub.3, 2 CH.sub.3). MS (ESI-TOF): calcd for C.sub.127H.sub.138N: (n=15 [M+H].sup.+) 1678.0858; found: 1677.9187. R.sub.f: 0.35 (CH.sub.2Cl.sub.2/MeOH 10:1).
[0165] Synthesis of PS.sub.15-Ala.sub.3-Fmoc 8. Following General Procedure A, PS.sub.15-NH.sub.2 (5.04 g, 3.01 mmol) and N-(9-fluorenylmethyloxycarbonyl)-L-alanyl-L-alanyl-L-alanine (1.50 g, 3.31 mmol) were dissolved in THF (250 mL). DIEA (1.54 mL, 9.02 mmol) and PyBOP (1.88 g, 3.61 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (6.0 g, 95%) was obtained as a pinkish solid. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.76 (d, J=7.8 Hz, 2H, aromatic H), 7.55 (d, J=7.5 Hz, 2H, aromatic H), 7.41 (t, J=7.4 Hz, 2H, aromatic H), 7.32 (t, J=7.3 Hz, 2H, aromatic H), =7.3-6.3 (m, 75H, Ph-H), 6.23 (s, 1H, NH), 5.20 (s, 1H, NH), 4.50-4.29 (m, 5H, Fmoc-CO.sub.2CH.sub.2, 3 CHCH.sub.3), 4.17 (m, 2H, fluorenyl CH), 3.02 (m, 2H, CH.sub.2NH), 2.5-0.5 (m, 67H, 15 CH.sub.2CHPh, 5 CH.sub.2, 3 CHCH.sub.3, COCH.sub.3).
[0166] Synthesis of PS.sub.15-Ala.sub.3-H 9. Following General Procedure B, PS.sub.15-Ala.sub.3-Fmoc (5.4 g, 2.56 mmol) was dissolved in CHCl.sub.3 (250 mL). Piperidine (5.06 ml, 51.11 mmol) was added, and the reaction mixture was stirred at room temperature overnight. The crude product was purified by column chromatography (silica gel, gradient CH.sub.2Cl.sub.2.fwdarw.CH.sub.2Cl.sub.2/MeOH 50:1). The final product (3.55 g, 75%) was obtained as yellowish powder. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.70 (m, 1H, NH), =7.36.3 (m, 75H, Ph-H), 5.90 (m, 1H, NH), 4.31 (m, 2H, CHCH.sub.3), 3.45 (m, 1H, CHCH.sub.3NH.sub.2), 3.02 (m, 2H, CH.sub.2NH), 2.5-0.5 (m, 67H, 15 CH.sub.2CHPh, 5 CH.sub.2, 3 CHCH.sub.3, COCH.sub.3).
[0167] Synthesis of PS.sub.15-Ala.sub.2-Ac S2. Following General Procedure A, PS.sub.15-NH.sub.2 (3.0 g, 1.79 mmol) and N-acetyl-1-alanyl-1-alanine (0.36 g, 1.79 mmol) were dissolved in THF (250 mL). DIEA (1.22 mL, 7.15 mmol) and PyBOP (1.4 g, 2.68 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (2.2 g, 67%) was obtained as pinkish solid. .sup.1H NMR (400 MHz, CDCl.sub.3) =7.36.3 (m, 75H, Ph-H), 6.10 (d, J=6.1 Hz, 1H, NH), 5.79 (s, 1H, NH), 4.42 (m, 1H, CHCH.sub.3), 4.29 (m, 1H, CHCH.sub.3), 3.02 (m, 2H, CH.sub.2NH), 2.5-0.5 (m, 67H, 15 CH.sub.2CHPh, 5 CH.sub.2, 3 CHCH.sub.3, COCH.sub.3).
[0168] Synthesis of PS.sub.15-Ala.sub.3-Ac S3. PS.sub.15-Ala.sub.3-H (1.2 g, 0.63 mmol) was dissolved in THF (50 mL). Acetyl chloride (136 mL, 1.9 mmol) and pyridine (0.205 mL, 2.54 mmol) were added and the reaction mixture was stirred overnight. The next day, the product was precipitated following General Procedure C. The final product (1.2 g, 98%) was obtained as white solid powder. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.3-6.3 (m, 75H, Ph-H), 5.0-4.6 (m, 3H, NH), 3.75 (m, 3H, CHCH.sub.3), 3.03 (m, 2H, CH.sub.2NH), 2.5-0.5 (m, 70H, 15 CH.sub.2CHPh, 5 CH.sub.2, 4 CHCH.sub.3, COCH.sub.3).
[0169] Synthesis of PS.sub.15-Ala.sub.4-Ac S4. Following General Procedure A, PS.sub.15-Ala.sub.3-H (602.8 mg, 0.319 mmol) and N-acetyl-1-alanine (46.0 mg, 0.351 mmol) were dissolved in THF (30 mL). DIEA (0.17 mL, 0.957 mmol) and PyBOP (602.9 mg, 1.69 mmol) were added. The reaction mixture was stirred overnight. The product was precipitated following General Procedure C. The final product (0.6 g, 95%) was obtained as a white solid powder. .sup.1H NMR (400 MHz, CDCl.sub.3 and TFA) =7.3-6.3 (m, 75H, Ph-H), 5.5-4.6 (m, 4H, CHCH.sub.3), 3.03 (m, 2H, CH.sub.2NH), 2.5-0.5 (m, 73H, 15 CH.sub.2CHPh, 5 CH.sub.2, 5 CHCH.sub.3, COCH.sub.3).
TABLE-US-00001 TABLE 1 Representative rheological data of M0-M5, D0-D2, polyisobutylenes of different molecular weights, as well as the blends M2/D2 99:1 (Example 1), M2/D2 95:5 (example 2), M2/D2 9:1 (Example 3), M2/D2 7:3 (Example 4), M2/D2 5:5 (Example 5), and M2/D2 1:9 (Example 6); storage moduli G, loss moduli G, loss factors tan , and shear viscosities |*|. Materials G/Pa G/Pa tan |*|Pa .Math. s) M0 0.22 139 623 139 M1 249 1250 5.02 1270 M2 42800 14300 0.334 45200 M3 251000 42900 0.171 254000 M4 510000 40200 0.079 511000 M5 633000 63900 0.101 636000 D0 25 2690 109 2690 D1 12300 70700 5.75 71800 D2 2000000 117000 0.059 2010000 PIB-NH.sub.2 (MW 1200) 0.19 32 168 32 H.sub.2N-PIB-NH.sub.2 (MW 1200) 4.99 234 46.9 235 PIB (MW 35000) 13400 24600 1.84 28000 PIB (MW 75000) 64500 42800 0.664 77500 PIB (MW 200000) 231000 25270 0.109 232000 PIB (MW 425000) 188100 11840 0.063 188400 M2/D2 99:1 123000 21800 0.177 125000 M2/D2 95:5 564000 47310 0.084 565000 M2/D2 9:1 495000 29610 0.060 496000 M2/D2 7:3 798000 52780 0.066 800000 M2/D2 5:5 1760000 124000 0.070 1760000 M2/D2 1:9 1500000 93880 0.063 1500000
TABLE-US-00002 TABLE 2 Shift factors log a.sub.T and log b.sub.T and activation energies E.sub.a obtained from the Arrhenius equation for the rheological measurements used in the time-temperature superposition master curves of polyisobutylenes of different molecular weights, pure M2 and D1, as well as the blends M2/D1 1:4 (Example 7), M2/PIB (MW 75000) 5:5 (Example 8), M2/PIB (MW 35000) 5:5 (Example 9), and M2/D2/PIB(MW 35000) 4:1:5 (Example 10). Materials T/ C. log a.sub.T log b.sub.T E.sub.a/J mol.sup.1 PIB (200k) 45 4.474 0.119 1055.8 10 1.677 0.028 25 0 0 105 2.199 0.111 PIB (75k) 45 3.889 0.17 986.91 10 1.684 0.021 25 0 0 65 1.317 0.0048 105 2.271 0.099 PIB (35k) 45 4.492 0.133 1080.16 10 1.689 0.04 25 0 0 65 1.302 0.025 105 2.356 0.166 M2 45 4.317 0.089 1040.6 10 1.65 0.066 25 0 0 105 2.255 0.015 D1 25 3.901 0.033 1735.8 10 2.991 0.137 25 0 0 25 3.93 0.024 M2/D1 1:4 10 2.998 0.112 1585.7 25 0 0 65 1.918 0.115 105 3.928 0.119 25 3.901 0.033 M2/PIB (75k) 5:5 45 4.305 0.033 1078.1 10 1.701 0.035 25 0 0 65 1.282 0.024 105 2.573 0.216 M2/PIB (35k) 5:5 45 4.075 0.145 1111.9 10 1.478 0.065 25 0 0 65 1.901 0.364 105 2.881 0.464 M2/D2/PIB (35k) 4:1:5 45 4.4 0.037 1136.3 10 1.6 0.057 25 0 0 65 1.841 0.186 105 2.677 0.265 Smactane 45 4.342 0.059 1194.3 10 1.746 0.05 25 0 0 65 1.8 0.035 105 3.208 0.045
TABLE-US-00003 TABLE 3 Storage moduli G and loss moduli G used as input in the finite element simulations, and the resonance frequencies and modal damping ratios resulting from these simulations for the reference materials Smactane, PIB (MW 200000), Soundcoat Dyad 601, and 3M ISD 130, as well as M2 and the blends M2/PIB (MW 75000) 5:5 (Example 8), M2/PIB (MW 35000) 5:5 (Example 9), and M2/D2/PIB(MW 35000) 4:1:5 (Example 10). Materials G/MPa G/MPa /Hz Smactane 1.01 0.47 36.1 1.8% PIB (200k) 0.317 0.148 35 0.70% Soundcoat Dyad 601.sup.2 1.26 0.756 36.5 2.6% 3M ISD 130.sup.1 0.094 0.036 34.6 0.20% M2 0.424 0.524 35.3 2.3% M2/PIB (75k) 5:5 0.509 0.442 35.396 1.89% M2/PIB (35k) 5:5 0.377 0.371 35.1 1.7% M2/D2/PIB (35k) 4:1:5 1.48 0.83 36.8 2.8%
TABLE-US-00004 TABLE 4 Calculation of the low-temperature damping properties. Loss modulus G and loss factor tan at 200 rad/s (32 Hz) from a rheological frequency sweep at room temperature, first resonance frequency in the forced vibration tests on sandwich structures, modal damping ratio at room temperature, and calculated dissipated energy W.sub.d at 45 C. and 25 rad/s for steel, Smactane, PIB (MW 200000), M2, M2/PIB (MW 35000) 5:5 (Example 9), and M2/D2/PIB(MW 35000) 4:1:5 (Example 10). G/MPa tan /Hz W.sub.d/J m.sup.3 Steel 32.2 0.4% Smactane 0.47 0.45 34.9 2.9% 5.98 PIB (MW 200000) 0.15 0.45 32.4 1.1% 3.95 M2 0.54 1.3 33.4 3.2% 13.29 M2/PIB (35k) 5:5 0.37 1.0 33.4 2.5% 11.09 M2/D2/PIB (35k) 4:1:5 0.83 0.55 35.6 3.4% 18.95
TABLE-US-00005 TABLE 5 Shift factors log a.sub.T and log b.sub.T for the rheological measurements used in the time-temperature superposition master curves of blends M3/S3/PIB (MW 35000) 9:3:12 (Example 13). Materials T/ C. log a.sub.T log b.sub.T M3/S3/PIB (35k) 45 4.220 0.220 25 2.856 0.115 10 1.600 0.170 25 0 0 65 2.454 0.033