FILLERS FOR POLYMERS

Abstract

This invention relates to a composite material comprising a core comprising an organosilica such as a polyhedral oligomeric silsesquioxane (POSS) and a functionalized elastomeric polymer such as poly(n-butyl acrylate) bonded onto said core. The elastomer is preferably functionalised with an amine moiety. The present invention also relates to a polymer comprising a resin such as Bisphenol A diglycidylether (DGEBA) and the aforementioned composite material, and a method for making the composite material. The composite material can improve both the material strength and material toughness of the polymer into which it is mixed.

Claims

1. A composite material comprising a chalcogen core and a functionalized elastomeric polymer bonded onto the chalcogen core.

2. The composite material according to claim 1, wherein the chalcogen core comprises a composition selected from the group consisting of organosilica, silica, clay, graphene oxide, carbon nanotubes, carbon black, glass fibres and any mixture thereof or wherein the chalcogen core comprises organosilica.

3. (canceled)

4. The composite material according to claim 2, wherein the organosilica is polyhedral oligomeric silsesquioxane (POSS) or wherein the polyhedral oligomeric silsesquioxane (POSS) is an octahedral oligomeric silsesquioxane.

5. (canceled)

6. The composite material according to claim 1, wherein the functionalized elastomeric polymer is covalently bonded onto the chalcogen core or wherein the elastomeric polymer is a thermoset elastomer or a thermoplastic elastomer.

7. (canceled)

8. The composite material according to claim 1, wherein the elastomeric polymer is selected from the group consisting of poly(n-butylacrylate), polysiloxane, polyisoprene, polybutadiene, polychloroprene, polyisobutylene, polyacrylate, polyvinyl polyvinylidine, poly(methyl methacrylate) and any mixture thereof or wherein the elastomeric polymer is poly(n-butylacrylate).

9. (canceled)

10. The composite material according to claim 1, wherein the elastomeric polymer is a polymer that has a glass transition temperature below −30° C.

11. Use composite material according to claim 1, wherein the elastomeric polymer is functionalized with a functional group selected from the group consisting of amine, epoxy, ester, hydroxyl, vinyl, urethane, isocyanate and any mixture thereof or wherein the elastomer polymer is functionalized with amine.

12. (canceled)

13. A polymer comprising a resin and a composite material comprising a chalcogen core and a functionalized elastomeric polymer bonded onto the chalcogen core.

14. The polymer according to claim 13, wherein the composite material is present in the polymer in an amount of up to 40 wt % or in the range of 0.1 wt % to 15 wt %.

15. (canceled)

16. The polymer according to claim 13, wherein the resin comprises polymerizable groups selected from the group consisting of amine, epoxy, ester, hydroxyl, vinyl urethane, isocyanate and any mixture thereof or wherein the resin comprises epoxy groups.

17. (canceled)

18. The polymer according to claim 13, wherein the resin is bisphenol A diglycidylether.

19. A method of synthesizing a composite material comprising a chalcogen core and a functionalized elastomeric polymer bonded onto the chalcogen core comprising: providing a chalcogen core; activating the core; contacting the activated core with an elastomeric polymer; and functionalizing the elastomeric polymer with a reactive functional group.

20. The method according to claim 19, wherein the chalcogen core comprises octahedral oligomeric silsesquioxane or wherein the octahedral silsesquioxane is octa(3-hydroxy-3-methylbutyldimethylsiloxy)-POSS.

21. (canceled)

22. The method according to claim 19, wherein the activating operation is performed by converting the hydroxyl group of octahydroxy poly octahedral silsesquioxane to a bromo group.

23. The method according to claim 19, wherein the activated core is octabromopropionyl poly octahedral silsesquioxane.

24. The method according to claim 19, wherein the elastomeric polymer is poly(n-butyl acrylate).

25. The method according to claim 19, wherein the contacting step is performed in the presence of a base.

26. The method according to claim 19, wherein the contacting step forms a covalent bond between the activated core and the elastomeric polymer.

27. The method according to claim 19, wherein the functional group is amine.

28. The method according to claim 19, wherein the functionalizing operation is performed by contacting the elastomeric polymer with an amino-containing compound.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0090] The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

[0091] FIG. 1

[0092] [FIG. 1] is a schematic showing the synthetic route of the POSS-(PnBA-NH.sub.2).sub.8.

[0093] FIG. 2

[0094] [FIG. 2] is a .sup.1 NMR spectra of (a) POSS-(PnBA-Br).sub.8 and (b) POSS-(PnBA-NH.sub.2).sub.8 in CDCl.sub.3.

[0095] FIG. 3

[0096] [FIG. 3] is the Gel Permeation Chromatography (GPC) trace of POSS-(PnBA-Br).sub.8 with THF as eluent.

[0097] FIG. 4

[0098] [FIG. 4] is a graph showing the thermogravimetric analysis (TGA) cure of POSS-(PnBA-NH.sub.2).sub.8.

[0099] FIG. 5

[0100] [FIG. 5] is the proposed reaction mechanism for filler dispersion in an epoxy polymer matrix.

[0101] FIG. 6

[0102] [FIG. 6] refers to a FESEM image (A) and TEM micro images having a scale bar representing 5 μm (B) and 1 μm (C), showing the dispersion of the filler in epoxy polymer matrix (at 2 wt % loading) having uniform size (≦1 (μm).

EXAMPLES

[0103] Non-limiting examples of the invention and a comparative example will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

Example 1

Composite Material

[0104] n-Butyl acrylate (n-BA) (≧99%, Aldrich) was purified by passing through a short column with neutral alumina oxide just before use to remove the inhibitor. Octa(3-hydroxy-3-methylbutyldimethylsiloxy)-POSS was purchased from Hybrid Plastics. 2-Bromoisobutyryl bromide (98%, Aldrich) and cysteamine (˜95%, Aldrich) were used as received. Diglycidyl ether of bisphenol A epoxy resin (DGEBA, D.E.R. 332) from Dow Chemicals and Diethyltoluenediamine (Ethacure 100-LC) hardener from Albemarle were used as the polymer matrix. The ethanol (laboratory grade) was supplied from Merck.

Synthesis of POSS-Br.SUB.8

[0105] POSS-Br.sub.8 was synthesized according to the procedure in He et al., Journal of Polymer Science: Part A: polymer chemistry Vol 46, 766-776 (2008). The characterization for it may be referred to this reference. In particular, POSS-OH.sub.8 (3.508 g, 2.05 mmol), triethylamine (3.20 mL, 23.00 mmol) and dried THF (70 mL) were added to a two-neck round-bottom flask under nitrogen atmosphere. After the mixture was cooled to 0° C. in an ice-water bath, 2-bromopropionyl bromide (2.69 mL, 23.00 mmol) was added dropwise to the mixture. The reaction mixture was stirred for 1 h at 0° C., then was further stirred overnight at room temperature. THF was evaporated under reduced pressure. The residue was dissolved in CH.sub.2Cl.sub.2, and the organic phase was successively washed with saturated NaCl aqueous solution and deionized water. The organic phase was dried by anhydrous MgSO.sub.4, followed by concentration. The crude product was purified by silica gel chromatography (first hexane, then THF) to provide the product as an extremely viscous light yellow oil (67% yield).

[0106] Synthesis of POSS-(PnBA-Br).sub.8

[0107] POSS-(PnBA-Br).sub.8 was synthesized via single-electron-transfer living-radical-polymerization (SET-LRP) as shown in FIG. 1. POSS-Br.sub.8 (0.577 g, 0.21 mmol), n-butyl acrylate (20 mL), N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA) (0.35 mL, 1.03 mmol) and acetone (10 mL) were added to a Schlenk flask with a rubber stopper. The reaction system was degassed by purging nitrogen flow for 15 min before adding nano copper powder (0.026 g, 0.41 mmol). The flask was purged for another 5 min and sealed under nitrogen atmosphere. The polymerization lasted for 1.5 h at 30° C., then was stopped by diluting with THF. The solution was passed through a short alumina column to remove the copper compound. After removal of most of solvent on rotary evaporator, the residue was precipitated in an excess mixture of methanol/water (v:v 1:1). The product was dried under vacuum until constant weight. (M.sub.n,NMR=22,480 g/mol) (46% yield). POSS-(PnBA-Br).sub.8 was characterized by .sup.1 H nuclear magnetic resonance (.sup.1H NMR) and Gel permeation chromatographic (GPC) equipments. The .sup.1H NMR spectrum is shown in FIG. 2a and the GPC spectrum is shown in FIG. 3.

[0108] Synthesis of POSS-(PnBA-NH.sub.2).sub.8

[0109] POSS-(PnBA-NH.sub.2).sub.8 was synthesized via thio-bromo “Click” reaction (as shown in FIG. 1). POSS-(PnBA-Br).sub.8 (3.50 g, 0.156 mmol), triethylamine (0.19 mL, 1.37 mmol) and cysteamine (0.105 g, 1.36 mmol) were dissolved in THF (20 mL). The reaction mixture was stirred overnight at room temperature, then concentrated under reduced pressure. The residue was precipitated in excess mixture of methanol/water (v:v 1:1) to obtain the product POSS-(PnBA-NH.sub.2).sub.8 (93% yield). POSS-(PnBA-NH.sub.2).sub.8 was characterized using .sup.1H NMR (FIG. 2b) and thermogravimetric analysis (TGA) (FIG. 4). As compared with the .sup.1H NMR spectrum of POSS-(PnBA-Br).sub.8 (FIG. 2a), the methane protons (—SCH.sub.2CH.sub.2NH.sub.2) and methane protons (—SCH.sub.2CH.sub.2NH.sub.2) of cysteamine can be seen more clearly (FIG. 2b), demonstrating successful modification of POSS-(PnBA-Br).sub.8 by amine groups. In the thermogravimetric analysis (TGA) cure of the POSS-(PnBA-NH.sub.2).sub.8 filler (FIG. 4), the decomposition stage ranging from about 265° C. to 430° C. could be ascribed to the polymer of n-butylacrylate. The weight fractions of the rubber poly(n-butylacrylate) and POSS are approximately 92.40% and 7.60%, respectively, which are consistent with the theoretical values (92.33% and 7.67%).

Example 2

POSS-Rub/Epoxy

[0110] POSS-(PnBA-NH.sub.2).sub.8 was dispersed in ethanol and sonicated for 30 min to improve its dispersion in the solvent medium. After that, epoxy resin (Epoxy D.E.R. 332) was mixed with the filler solution and the mixture was homogenized for 30 min. The solvent was removed at 75° C. under vacuum condition after homogenization. After the solvent is completely removed, a hardener (Ethacure 100-LC from Albemarle) was homogeneously mixed with the mixture at a weight ratio of 61 g of epoxy resin to 16 g of hardener. After that, the mixture was degassed under vacuum at 40° C. for 2 h, and poured into a glass mould. Then, the mixture was cured at 130° C. for 2 h, 160 for 2 h and 230° C. for 5 h. This sample is denoted as POSS-Rub/Epoxy. This process is shown in FIG. 5, where 502 denotes the elastomeric polymer poly(n-butylethylene), 504 denotes the epoxy resin and 506 denotes heating. FIG. 6 shows the morphology of the filler in the polymer matrix and the filler dispersion. As can be seen from FIG. 6, POSS-(PnBA-NH.sub.2).sub.8 dispersed in the polymer matrix has a uniform size (less than 1 micron) within the matrix.

Comparative Example 1

Neat DER 332

[0111] Epoxy resin (Epoxy D.E.R. 332 from Dow Chemicals) was mixed with hardener (Ethacure 100-LC from Albemarle) and the mixture was homogenized for 30 min. The weight ratio is 61 g of resin to 16 g of hardener, according to the material datasheet recommendation. After that, the mixture was degassed under vacuum at 40° C. for 2 h and poured into a glass mould. Then, the mixture was cured at 130° C. for 2 h, 160 for 2 h and 230° C. for 5 h. This sample is denoted as Neat DER 332.

Comparative Example 2

POSS/Epoxy

[0112] Commercial Octa-Ammonium POSS (from Hybrid Plastics) was dispersed in ethanol and sonicated for 30 min to improve the filler dispersion in solvent medium. After that, epoxy resin (Epoxy D.E.R. 332) was mixed with the POSS solution and the mixture was homogenized for 30 min. The solvent was removed at 75° C. under vacuum condition after homogenization. After the solvent was completely removed, the hardener (Ethacure 100-LC from Albemarle) was homogeneously mixed with the mixture with weight ratio of 61 g of epoxy resin to 16 g of hardener. After that, the mixture was degassed under vacuum at 40° C. for 2 h, and poured into a glass mould. Then, the mixture was cured at 130° C. for 2 h, 160 for 2 h and 230° C. for 5 h. This sample is denoted as POSS/Epoxy.

Example 3

Comparison

[0113] Method of Characterization

[0114] High resolution Transmission Electron Microscopy (HRTEM) micrographs were taken with a Philips CM300 at 300 kV. The samples with a thickness of approximately 100 nm were microtomed at room temperature using a diamond knife and collected on 200 mesh copper grids.

[0115] Field Emission Scanning Electron Microscope (FESEM) micrographs were taken using FESEM, JEOL-6700F conducted in high resolution mode with a large objective aperture at 200 kV.

[0116] Dynamic Mechanical Analysis: The storage modulus and glass transition temperature (Tg) of the nanocomposite were measured with a TA 2980 dynamic mechanical analyzer using single cantilever mode. The geometry of the specimens is 35 mm (length)×10 mm (width)×3 mm (thickness). Scans were conducted in a temperature range of 30-250° C. at a heating rate of 3° C./min and a frequency of 1 Hz.

[0117] Mechanical Property: The flexural modulus was determined by 3-point bending test according to the ASTM Standard D 790-96. The composite was cut to specimen size of 55×13×2.2 mm.sup.3. The tests were conducted with crosshead speed of 1.2 mm/min, at a span length of 40 mm. The sample was cut to dog-bone shape for tensile modulus test, according to ASTM D 638-03. The dimension was 55×3.2 to 3.5×2.2 mm.sup.3. The test was carried using the Instron 5569 Table Universal testing machine at tensile speed of 1 mm/min.

[0118] Impact property: The impact resistance was determined using pendulum-impact tester, according to ASTM Standard D 4812-99.

[0119] Comparison

[0120] Table 1 shows the mechanical, thermal and impact properties of the studied composite materials. It can be seen that addition of POSS-(PnBA-NH.sub.2).sub.8 significantly improves both materials strength (evaluated via the tensile property) and toughness (evaluated via the impact resistance). With only 1 wt % of POSS-(PnBA-NH.sub.2).sub.8, the impact resistance, elongation at break and tensile strength increased almost 77%, 110%, and 45%, respectively. The improvement of the nanocomposite strength and toughness is clearly due to the incorporation of POSS-(PnBA-NH.sub.2).sub.8 which contains the rigid segment (i.e., POSS) to improve the material strength and the soft-ductile segment (i.e., PnBA) to enhance the material toughness and flexibility.

[0121] For comparison purpose, the toughness and strength of a polymer matrix comprising just the commercial available POSS without modification (POSS/Epoxy) was evaluated. Unlike the result with POSS-Rub/Epoxy, the strength of the polymer increased with the POSS filler content (i.e., ↑10% with 1 wt % filler), but the impact resistance significantly decreased (i.e., ↓>50% with 1 wt % filler). In addition, When the POSS content increased by more than 1 wt %, only the nanocomposite strength increased, whereas its toughness reduced significantly. This result indicates that the unmodified POSS solely improves the material strength, but not the material toughness.

[0122] The experiment results suggest that the typical filler cannot solve the contradicting problem between material strength and material toughness, but POSS-(PnBA-NH.sub.2).sub.8 can solve this challenge by improving material strength as well as material toughness.

TABLE-US-00001 TABLE 1 Summary of mechanical, thermal and impact properties of neat epoxy resin, POSS/epoxy and POSS-Rub/epoxy nanocomposite. Glass Fracture Filler Tensile Property Impact transition toughness, Content Max Strength Tensile E Elongation at Storage Resistance temperature, K.sub.ic Sample (wt %) (MPa) (MPa) break (%) E (MPa) (kJm.sup.2) T.sub.g (° C.) (MPa .Math. m.sup.1/2) Neat DER 332 0 48.4 ± 4.19 2.4 ± 0.02 2.7 ± 0.27 2.5 ± 0.17 31.16 ± 5.82 203.4 ± 0.18 1.25 ± 0.08 POSS/Epoxy 0.5 49.0 ± 12.6 2.4 ± 0.11 3.1 ± 1.22 2.4 ± 0.09 16.19 ± 1.68 199.5 ± 1.12 1.25 ± 0.02  (↑ 1%) (↑ 15%) (↓ 48%) 1 54.3 ± 10.4 2.4 ± 0.05 3.0 ± 0.81 2.5 ± 0.15 14.38 ± 3.30 195.6 ± 0.08 1.29 ± 0.88 (↑ 10%) (↑ 11%) (↓ 54%)  (↑ 3%) 1.5 59.9 ± 11.9 3.1 ± 0.33 2.3 ± 0.83 2.8 ± 0.11 15.27 ± 1.72 188.6 ± 1.12 1.54 ± 0.13 (↑ 23%) (↓ 15%) (↓ 51%) (↑ 23%) 2 66.8 ± 2.75 3.3 ± 0.06 2.4 ± 0.11 3.0 ± 0.02 10.03 ± 15.79 145.8 ± 0.93 1.65 ± 0.56 (↑ 38%) (↓ 11%) (↓ 68%) (↑ 32%) POSS- 0.5 67.5 ± 8.35 2.4 ± 0.02 4.7 ± 1.22 2.4 ± 0.13 34.96 ± 4.24 189.1 ± 2.13 1.26 ± 0.05 Rub/Epoxy (↑ 39%) (↑ 74%) (↑ 13%) (↑ <1%) 1 69.6 ± 11.6 2.4 ± 0.05 5.7 ± 2.15 2.5 ± 0.08 55.12 ± 3.51 190.1 ± 1.25 1.49 ± 0.03 (↑ 45%) (↑ 110%)  (↑ 77%) (↑ 20%) 1.5 74.2 ± 14.5 2.5 ± 0.07 4.9 ± 1.59 2.4 ± 0.12 45.32 ± 4.26 188.2 ± 0.59 1.55 ± 0.54 (↑ 53%) (↑ 82%) (↑ 45%) (↑ 24%) 2 68.9 ± 4.33 2.5 ± 0.01 4.2 ± 0.58 2.4 ± 0.20 42.64 ± 2.06 185.2 ± 0.58 1.63 ± 0.11 (↑ 43%) (↑ 56%) (↑ 37%) (↑ 30%) Note: E = modulus

INDUSTRIAL APPLICABILITY

[0123] The composite material may be useful as a filler in a polymer matrix to improve both the material strength and material toughness at the same time. The composite material may be useful as an alternative filler for polymers.

[0124] The polymer comprising the composite material may be useful in paints, coatings and adhesives. The polymer comprising the composite material may be useful in structural composite materials. The polymer comprising the composite material may also be useful in structural components in industrial tooling, infrastructure, electronics, automotive, marine, aerospace, off-shore and biological applications. The polymer comprising the composite may be further useful in sporting goods and in packaging materials. The method for manufacturing the composite material may be useful in time- and cost-effective manufacture of the composite material.

[0125] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.