A METHOD TO PREPARE A PRECURSOR FOR A POLYMER OR TO PREPARE A POLYMER COMPRISING AT LEAST ONE UNIT HAVING A TERTIARY AMINE AND A PENDANT CARBOXYL GROUP AND A PRECURSOR OR POLYMER COMPRISING SUCH UNIT

Abstract

The invention relates to a method to prepare a precursor for a polymer or to prepare a polymer, the polymer comprising at least one unit of formula (I) or at least one unit of formula (II) having a tertiary amine and a pendant carboxyl group

##STR00001##

Furthermore the invention relates to a precursor or polymer comprising at least one unit of formula (I) and/or at least one unit of formula (II) and to the use of such precursor or such polymer in extrusion, injection moulding, compression moulding, transfer moulding, foam moulding, thermoforming, rotation moulding or 3D printing

Claims

1. A method to prepare a polymer or to prepare a precursor for a polymer, said method comprising the steps of a) providing at least one compound Y comprising a first functional group and a second functional group, said first functional group comprising an anhydride group, a pair of carboxyl groups or a pair of derivatives of a carboxyl group, said anhydride group, said pair of carboxyl groups or said pair of derivatives of a carboxylic group of said first functional group comprising a first carbonyl group, a second carbonyl group, a first carbon atom positioned next to said first carbonyl group, a second carbon atom positioned next to said second carbonyl group and optionally a third carbon atom positioned between said first carbon atom and said second carbon atom, said first carbon atom, said second carbon atom and said optional third carbon atom being independently from each other substituted or non-substituted and, said second functional group comprising a polymerisable group P1, whereby in case a unsaturated bond is present between said first carbon atom and said second carbon atom, said unsaturated bond between said first carbon atom and said second carbon atom is not considered as polymerisable group P1 of said second functional group and whereby in case the bond between said first carbon atom and said second carbon atom is part of a cyclic or aromatic structure comprising an unsaturated bond in said cyclic or aromatic structure, said unsaturated bond present in said cyclic or aromatic structure is not considered as polymerisable group P1 of said second functional group; b) providing an alcohol Z or a mixture of alcohols comprising alcohol Z or reacted with alcohol Z, said alcohol Z comprising at least one hydroxyl functional group and at least one polymerisable group P2, said alcohol Z further comprising a nitrogen atom, said nitrogen atom having three substituents comprising at least one carbon atom, said alcohol Z comprising a first carbon atom, a second carbon atom and optionally a third carbon atom between said nitrogen and said at least one hydroxyl functional groups of said alcohol Z, said first carbon atom, said second carbon atom and said optional third carbon atom being independently from each other substituted or non-substituted; c) contacting said compound Y provided in step a) and said alcohol Z or said mixture of alcohols provided in step b).

2. The method according to claim 1, wherein said polymerisable group P1 of said second functional group of compound Y comprises an unsaturated carbon-carbon, a carboxyl group, an anhydride group, a pair of carboxyl groups or a pair of derivatives of a carboxyl group.

3. The method according to claim 1, wherein said compound Y comprises a polyanhydride comprising at least two cyclic anhydride groups.

4. The method according to claim 1, wherein said polymerisable group P2 of said alcohol Z comprises an unsaturated carbon-carbon bond, a carboxyl group, a derivative of a carboxyl group or a hydroxyl functional group.

5. The method according to claim 1, wherein said compound Z comprises a beta-amino-alcohol having one, two or three hydroxyl functional groups.

6. The method according to claim 1, wherein said compound Y and said alcohol Z are contacted in step c) in a molar ratio of alcohol Z to compound Y lower than 2, whereby the molar ratio is defined in terms of the total number of hydroxyl functional groups of alcohol Z or the total number of hydroxyl functional groups of all alcohols of the mixture of alcohols comprising alcohol Z in case mixture of alcohols is used divided by the total number of anhydride functional groups and pairs of carboxyl groups or derivatives of a carboxyl group of compound Y.

7. The method according to claim 1, wherein said alcohol Z is provided by contacting an amine V and a compound X, said amine V comprising at least one reactive NH bond and said compound X comprising at least one epoxide group, in a molar ratio V to X ranging between 0.5 and 1.5, said molar ratio being defined in terms of the number of said reactive NH bonds and the number of said epoxide functional groups.

8. A precursor for preparing a polymer, said precursor comprising at least one unit of formula (I) and/or at least one unit of formula (II) ##STR00022## with C.sub.1, C.sub.2, C.sub.3 and C.sub.4 being carbon atoms, whereby C.sub.1 and C.sub.2 being positioned next to a carbonyl group, C.sub.3 being positioned next to an oxygen atom and C.sub.4 being positioned next to a nitrogen atom; A comprising a linear saturated or unsaturated bond between C.sub.1 and C.sub.2 or comprising a chain connecting C.sub.1 and C.sub.2 by means of an additional carbon atom C.sub.A, whereby at least one of C.sub.1, C.sub.2 or C.sub.A is substituted with a group R.sub.x, said group R.sub.x being a polymerisable group or a polymeric group; A comprising a bond between C.sub.1 and C.sub.2 or comprising a chain connecting C.sub.1 and C.sub.2 by means of an additional carbon atom C.sub.A, whereby said bond A or said chain A is a part of an aromatic or a cyclic structure, said aromatic or said cyclic structure being substituted with at least one group R.sub.x, said group R.sub.x being a polymerisable group or a polymeric group; B comprising a bond between C.sub.3 and C.sub.4 or a chain connecting C.sub.3 and C.sub.4 by means of an additional carbon atom C.sub.B, with each of C.sub.3, C.sub.4 and C.sub.B being independently from each other non-substituted or substituted, with the bond B between C.sub.3 and C.sub.4 being a linear saturated bond or unsaturated bond or with the bond B between C.sub.3 and C.sub.4 or the chain B connecting C.sub.3 and C.sub.4 being part of an aromatic or cyclic structure; R.sub.3 and R.sub.4 not being hydrogen; and said at least one unit of formula (I) and/or said at least one unit of formula (II) having at least one open attachment site allowing to form a polymer.

9. The precursor according to claim 8, wherein the substituents of the carbon atoms C.sub.1, C.sub.2 and C.sub.A are independently from each selected from the group consisting of hydrogen, a halogen, a hydroxyl functional and substituents comprising at least one carbon and/or wherein in case one or more of the carbon atoms C.sub.1, C.sub.2 and C.sub.A belong to an aromatic or cyclic structure, said aromatic or cyclic structure being substituted a substituent selected from the group consisting of hydrogen, a halogen, a hydroxyl functional and substituents comprising at least one carbon; and/or wherein the substitutents of the carbon atoms C.sub.3, C.sub.4 and C.sub.B are independently from each selected from the group consisting of hydrogen, a halogen, a hydroxyl functional and substituents comprising at least one carbon and/or wherein in case one or more of the carbon atoms C.sub.3, C.sub.4 and C.sub.B belong to an aromatic or cyclic structure, said aromatic or cyclic structure being substituted a substituent selected from the group consisting of hydrogen, a halogen, a hydroxyl functional and substituents comprising at least one carbon.

10. The precursor according to claim 8, wherein said unit of formula (I) or said unit of formula (II) comprises a further polymerisable group or polymeric group R.sub.y in addition to said polymerisable group or polymeric group R.sub.x.

11. The precursor according to claim 8, wherein said precursor forms a network.

12. The precursor according to claim 11, wherein said network forms a covalent adaptable network.

13. A polymer precursor for preparing a polymer, said precursor comprising at least one unit of formula (I) and/or at least one unit of formula (II) ##STR00023## with C.sub.1, C.sub.2, C.sub.3 and C.sub.4 being carbon atoms, whereby C.sub.1 and C.sub.2 being positioned next to a carbonyl group; whereby C.sub.3 being positioned next to an oxygen atom and C.sub.4 being positioned next to a nitrogen atom; A comprising a linear saturated or unsaturated bond between C.sub.1 and C.sub.2 or comprising a chain connecting C.sub.1 and C.sub.2 by means of an additional carbon atom C.sub.A, whereby at least one of C.sub.1, C.sub.2 or C.sub.A is substituted with a group R.sub.x, said group R.sub.x being a polymeric group; A comprising a bond between C.sub.1 and C.sub.2 or comprising a chain connecting C.sub.1 and C.sub.2 by means of an additional carbon atom C.sub.A, whereby said bond A or said chain A is a part of an aromatic or a cyclic structure, said aromatic or said cyclic structure being substituted with at least one group R.sub.x, said group R.sub.x being a polymeric group; B comprising a bond between C.sub.3 and C.sub.4 or a chain connecting C.sub.3 and C.sub.4 by means of an additional carbon atom C.sub.B, with each of C.sub.3, C.sub.4 and C.sub.B being independently from each other non-substituted or substituted, with the bond B between C.sub.3 and C.sub.4 being a linear saturated bond or unsaturated bond or with the bond B between C.sub.3 and C.sub.4 or the chain B connecting C.sub.3 and C.sub.4 being part of an aromatic or cyclic structure; R.sub.3 and R.sub.4 not being hydrogen; and said at least one unit of formula (I) and/or said at least one unit of formula (II) having at least one open attachment site allowing to form a polymer.

14. The precursor according to claim 8 for use in extrusion, injection moulding, compression moulding, transfer moulding, foam moulding, thermoforming, rotation moulding or 3D printing.

15. The polymer according to claim 13 for use in extrusion, injection moulding, compression moulding, transfer moulding, foam moulding, thermoforming, rotation moulding or 3D printing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0140] The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

[0141] FIG. 1a and FIG. 1b shows a strategy for the synthesis of a polymer according to the present invention;

[0142] FIG. 2 shows the glass transition temperature of different networks having an increased amount of added beta-amino diol (N?0 to N?100) synthesised according to the strategy shown in FIG. 1;

[0143] FIG. 3 shows the tensile properties of the different networks having an increased amount of added beta-amino diol. FIG. 3(a) shows the tensile strength (top) and the maximum strain (bottom) as a function of the increased amount of added beta-amino diol and FIG. 3(b) shows the stress (MPa) as a function of the strain (%);

[0144] FIG. 4 shows the stress-relaxation curves of the different networks having an increased amount of added beta diol (N?0 to N?100) at 160? C.;

[0145] FIG. 5 compares the stress-relaxation curves at 160? C. of a composition having no amine (N?0), a composition having an internal tertiary amine (N?100) and a composition having an external amine (N?0+tributyl amine);

[0146] FIG. 6 shows the frequency sweep measurements at different temperatures of N?20;

[0147] FIG. 7 shows a further strategy for the synthesis of a polymer according to the present invention;

[0148] FIG. 8 shows the glass transition temperature of different networks having an increased amount of Pripol 2033 in the polyol mixture synthesized according to the strategy shown in FIG. 7;

[0149] FIG. 9 shows a still a further strategy for the synthesis of a polymer according to the present invention.

DESCRIPTION OF EMBODIMENTS

[0150] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings are only schematic and are non-limiting. The size of some of the elements in the drawing may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0151] When referring to the endpoints of a range, the endpoints values of the range are included.

[0152] When describing the invention, the terms used are construed in accordance with the following definitions, unless indicated otherwise.

[0153] The term and/or when listing two or more items, means that any one of the listed items can by employed by itself or that any combination of two or more of the listed items can be employed.

[0154] The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

EXAMPLES

Example 1

[0155] a. Material Synthesis

[0156] FIG. 1(a) shows the synthesis of a network 6 according to the present invention by adding a diol 3 or a combination of diols 3, 5, and a triol 4 to a dianhydride monomer 1. FIG. 1(b) shows the formation of a network of a composition according to the present invention schematically.

[0157] The diol comprises for example 1,6-hexanediol (HD, 3). In case a combination of diols is used examples comprises 1,6-hexanediol (HD, 3) and N-methyl diethanolamine (MDEA, 5). The triol comprises for example trimethylolpropane (TMP, 4). The dianhydride used in the example was synthesized from Pripol 2033 (reference 2 in FIG. 1).

[0158] First, a benchmark network was synthesized with 1,6 hexanediol (HD,3) and trimethylolpropane (4) in the polyol mixture. Next, a library of tertiary amine containing materials was synthesized by a drop-in approach by gradually replacing hexanediol (3) with N-methyl diethanolamine (MDEA, 5). The corresponding networks were named N-x, where x denotes the percentage of amino-alcohol in the diol mixture. The amounts of diols, triols and dianhydride is specified in Table 1.

[0159] More Details about the Synthesis Method are Given Below:

[0160] An amount trimethylolpropane (TMP) is put in a plastic cup (SpeedMixer?) together with a mixture of 1-6-hexanediole (HD) and N-methyl diethanolamine (M DEA). The cup is subsequently heated in an oven at 80? C. for 5 min to melt the alcohol mixture. Pripol-dianhydride was added and the monomers were mixed using a SpeedMixer? (3500 rpm, 60 s). The heating and mixing step was repeated once to obtain a homogeneous mixture. The cup was put in an oven at 100? C. for 2 h, followed by a curing under vacuum at 100? C. for 16 h to remove last traces of toluene (from dianhydride) and suppress amine oxidation. The obtained (foamed) network was cut in small pieces and pressed in a hot press for 20 min (or 60 min for N?0) at 150? C. (2t) to obtain a homogeneous and transparent network.

TABLE-US-00001 TABLE 1 Pripol dianhydride Network (mmol) HD (mmol) MDEA (mmol) TMP (mmol) N-0 6.20 2.48 2.48 N-20 6.20 1.98 0.50 2.48 N-40 6.20 1.49 0.99 2.48 N-60 6.20 0.99 1.49 2.48 N-80 6.20 0.50 1.98 2.48 N-100 6.20 2.48 2.48

[0161] b. Material Properties

[0162] To evaluate the materials the glass transition temperature, tensile strength and the dynamic properties such as stress-relaxation of the different compositions (N?0 to N?100) were determined.

[0163] Glass Transition

[0164] Differential scanning calorimetry (DSC) was used to measure the glass transition temperatures of the networks. DSC analyses were performed with a Mettler-Toledo 1/700 under nitrogen atmosphere. The samples were analyzed in aluminium sample pans which contained 5-15 mg of the sample. Glass transition temperatures (T.sub.g's) were determined in the second heating step using the STARe software of Mettler-Toledo. Measurements were performed in a temperature range of ?50-100? C. with a rate of 10 Kmin.sup.?1. The glass transition temperatures of the different networks having an increased amount of added beta-amino diol (N?0 to N?100) are shown in FIG. 2.

[0165] The benchmark material N?0 had a rather low glass transition temperature of 10? C., resulting from the flexible Pripol-dianhydride. Interestingly, by replacing hexanediol (partially) with MDEA, the T.sub.g linearly increased as a function of amine percentage, reaching up to 38? C. for N?100. This trend can be rationalized by the decrease in free volume that is caused by the additional ionic interactions.

[0166] Tensile Strength

[0167] Stress-strain experiments were performed with a Tinius-Olsen H1OKT tensile tester using a strain rate of 10 mm/min, with a pre-load stress of 0,005 Pa. Flat dog bone-type specimen with an effective gage length of 12 mm, a width of 2 mm and a thickness varying between 1.5 and 2 mm were used. The samples were cut using a Ray-Ran dog bone cutter.

[0168] The results are shown in FIG. 3. FIG. 3(a) (top) shows the Young's- or E-modulus as a function of the increasing amount of beta-amino diol. FIG. 3(a) (bottom) shows the maximum strain (%) as a function of the increasing amount of beta-amino diol. FIG. 3(b) shows the stress (MPa) as a function of the strain (%)

[0169] From FIG. 3(a) (top) can be concluded that the Young's- or E-modulus, a measure of the stiffness, is drastically increasing from N?0 up to N?60 by almost a factor of ten (39 and 290 MPa respectively). However, this increase tended to level off at higher amine concentration. Linked to the E-modulus, the maximal strain of the networks showed a decreasing trend, making them more brittle (FIG. 3(a) (bottom)). Interestingly, the stress at break remained more or less constant for all the materials (FIG. 3(b)). Although applicant does not want to be bound by any theory, the observed trend can be assigned to the increased cross-link density caused by the ionic bonds.

Dynamic Properties

Stress-Relaxation

[0170] The dynamic behaviour of the networks was quantified with stress relaxation measurements using rheology.

[0171] The rheology experiments were conducted on an Anton-Paar MCR 302 rheometer in shear geometry with a plate diameter of 8 mm. A compression force between 0.1 N and 5N and a deformation within the linear viscoelastic region were applied. The samples had a thickness of around 2 mm and were cut with a hollow puncher of Boehm with a diameter of 8 mm. In particular, stress-relaxation, frequency sweep and creep experiments were carried out by this instrumentation.

[0172] The relaxation curves of the different networks at 160? C. are depicted in FIG. 4. The acceleration effect of the neighbouring tertiary amine was clearly observed as well on material level. Indeed, going from the benchmark network (N?0) to N?20 caused an immense drop in relaxation time (515 seconds vs 28 seconds respectively). Faster exchange could be obtained by further increasing the amine-content. Although this further acceleration was less pronounced compared to the first jump (from 0 to 20%), a relaxation time of ?1.1 seconds was finally obtained for N?100. This means that the complete replacement of hexanediol with N-methyl diethanolamine caused an increase in exchange kinetics with a factor of 500.

[0173] The above described results show an acceleration of the transesterification of a composition according to the present invention. Although applicant does not want to be bound by any theory, the acceleration seems to be due to the double neighbouring group effect. In order to verify the double internal catalysis hypothesis, the stress-relaxation and frequency sweep measurements were determined for a reference material containing the same amount of amine as the N?100 sample but as an external amine. For the reference sample 100% (with respect to diol) of tributyl amine was added to the N?0 formulation. Although an acceleration of the exchange rate was observed for the reference network, the internal amine again exceeded this effect with a factor of five (1.1 s and 5.5 s respectively, see FIG. 5(a)).

[0174] In the previously mentioned determination of the dynamic properties stress-relaxtion experiments were used. The data obtained from such a stress-relaxation experiments are typically normalised with respect to the initial relaxation modulus. To do this in a reproducible way, an initial modulus (Go) is determined from the plateau in the beginning of the measurement, as shown for example for N?0 in FIG. 5(a). However, if relaxation is fast (T<10), this plateau is very small or even absent, which makes the normalisation less convenient and thus the calculation of the relaxation time (?) less accurate. As exemplified in the relaxation curve of N?100 (??1.1 s) in FIG. 5(a), the ultra-fast exchange of the double-NGP networks resulted in relaxation curves without such initial plateau.

[0175] Alternative to stress-relaxation, frequency sweep experiments can be used to measure the relaxation time, which is then defined as the inverse of the angular frequency (?) at the cross-over between the storage (G) and loss modulus (G). Frequency sweeps measurements were performed on N?20, although the transesterification rate in this network was too slow to observe a cross-over (FIG. 6). In this case, the point of interest was the plateau in storage modulus between 1 and 10 rad/s. Because this plateau value remained constant for every temperature, this confirmed that exchange happened without a significant drop in cross-link density.

[0176] c. Industrial Relevant Processing

Melt-Flow Index

[0177] Extrusion is one of the most important and used techniques in the processing of thermoplastics. As a prerequisite for extrusion, polymer materials need to show sufficient flow at the applied temperatures. Because of the low relaxation times that were obtained, the possibility to use the composition N?100 in industrial processes and in particular in extrusion was explored. The flow of N?100 was determined via a Melt-Flow Index (MFI) measurement using a Zwick 4100 apparatus, where a sample of the network was pushed through a die having a diameter of 2.095 mm at 150? C. under a standardised load of 2.16 kg. Subsequently, the MFI was calculated from the mass that could flow through the die as a function of time. For N?100 at 150? C. a MFI of 6 g/10 min was calculated. It is important to note that the flow had stopped quickly after cooling at the bottom plate, which resulted in a good retention of the shape of the rods.

Extrusion

[0178] After the MFI-measurements of N?100, which showed sufficient flow, processing via extrusion was attempted with the use of a double-screw mini-extruder (Haake Minilab of Thermo Scientific) at 150? C. Initially, a speed of 5 rpm was applied, which yielded a homogeneous extrudate. At higher speeds some defects were observed. Nevertheless, the extrusion experiments provided an interesting proof of concept to process the double NGP networks according to the present invention.

Determination of Network Dissociation During Processing

[0179] In the MFI-measurement and extrusion, viscous flow was observed for N?100 at 150? C. Interestingly, in both experiments, no further flow was observed when the applied heat and pressure were removed, which enabled a good retention of the obtained shape.

[0180] Although applicant does not want to be bound by any theory it is assumed that the ultra-fast relaxation that was observed for N?100 (and other double-NGP networks) was caused by a fast reshuffling of the cross-links rather than a decross-linking. This explains the stable shape of the network after processing and avoids the need of an additional heating step afterwards to re-cure the material.

Example 2

[0181] FIG. 7 shows the synthesis of a network 8 according to the present invention by adding a polyol mixture comprising N-methyl diethanolamine (MDEA, 5) and optionally Pripol 2033 (2) and trimethylolpropane (TMP, 4) to 4,4-(4,4-Isopropylidenediphenoxy)bis(phthalic anhydride) (bisphenol A dianhydride, 7) using dioxane as solvent.

[0182] The ratio of MDEA and Pripol 2033 in the polyol mixture was varied according to the amounts specified in Table 2. The resulting networks were named P-x, where x denotes the percentage of Pripol 2033 in the mixture of MDEA and Pripol 2033.

[0183] More Details about the General Synthesis Method are Given Below:

[0184] The required amounts of MDEA, Pripol 2033, and TMP as specified in Table 2 were dissolved in 5 mL dioxane in a plastic cup (SpeedMixer?). Solid bisphenol A dianhydride (9.61 mmol) was added and the monomers were mixed using a SpeedMixer? (2500 rpm, 120 s). The resulting mixture was heated to 100? C. for 10 min under ambient atmosphere after which the mixing step was repeated. The heating and mixing step was repeated once or optionally twice to obtain a homogeneous solid or highly viscous liquid. The mixture was heated a further 40 min to 100? C. under ambient atmosphere, followed by a curing under vacuum at 100? C. overnight (approximately 16 h). The obtained (foamed) network was ground to a fine powder and finally heated to 160? C. for 60 min under ambient atmosphere to remove the last traces of solvent.

TABLE-US-00002 TABLE 2 Bisphenol A Pripol dianhydride MDEA 2033 TMP T.sub.g T.sub.deg, 5% Network (mmol) (mmol) (mmol) (mmol) (? C.) (? C.) P-0 9.61 3.84 0 3.84 154 311 P-10 9.61 3.46 0.38 3.84 146 299 P-20 9.61 3.07 0.77 3.84 140 279 P-30 9.61 2.69 1.15 3.84 136 283 P-40 9.61 2.31 1.54 3.84 126 324 P-50 9.61 1.92 1.92 3.84 117 341

[0185] To evaluate the materials, their glass transition temperature and degradation temperature were determined via dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively.

[0186] DSC analyses were performed with a Mettler-Toledo 1/700 under nitrogen atmosphere. The samples were analyzed in aluminium sample pans which contained 5-20 mg of the sample. The samples were heated from an initial temperature to 150? C., cooled to the initial temperature, heated to 200? C., cooled to the initial temperature and heated to 200? C. The initial temperature was at least 40? C. below the glass transition temperature (T.sub.g) of the material and the heating/cooling rate was 10? C.min.sup.?1. T.sub.g's were determined in the third heating step using the STARe software of Mettler-Toledo. In the case of networks P-x, the initial temperature was 35? C. and the obtained glass transition temperatures are listed in Table 2 and shown in FIG. 8.

[0187] Thermogravimetric analyses were performed with a Mettler Toledo TGA/SDTA 851e instrument under nitrogen atmosphere at a heating rate of 10? C. min.sup.?1 from 25? C. to 800? C. The thermograms were analyzed with the STARe software of Mettler-Toledo. The temperature at which 5% of the initial sample mass had volatilized (T.sub.deg, 5%) for each network P-x is listed in Table 2.

Example 3

[0188] FIG. 9 shows the synthesis of a network 14 according to the present invention by first reacting N-methylethanolamine (NMEA, 10) and/or dibutylamine (DBA, 11) with a molecule 9 comprising two epoxide groups. The produced polyol mixture 12 is then mixed with a dianhydride monomer 13 to obtain network 14.

[0189] Epoxide 9 comprises for example bisphenol A diglycidyl ether (9a), 1,4-butanediol diglycidyl ether (9b), or poly(propylene glycol) diglycidyl ether (Mn=380 g/mol, 9c). Corresponding polyol mixtures 12a, 12b, or 12c with an average alcohol functionality of 2.5 were obtained by mixing the respective epoxide 9 with NMEA and DBA according to the amounts specified in Table 3. Dianhydride monomer 13 comprises for example 4,4-(4,4-Isopropylidenediphenoxy)bis(phthalic anhydride) (13a), 4,4-oxydiphthalic anhydride (13b), 3,3,4,4-biphenyltetracarboxylic dianhydride (13c). The networks were named 14xy where x denotes the used polyol 12x and y denotes the used dianhydride monomer 13y and were obtained by mixing the respective compounds according to the amounts specified in Table 4.

[0190] More Details about the General Synthesis Method are Given Below:

[0191] The required amounts of epoxide 9, NMEA, and DBA as specified in Table 3 were mixed and heated to 100? C. overnight in a closed glass vial, after which the mixture was allowed to cool to room temperature. Next, finely ground dianhydride monomer 13 was added to an aliquot of the obtained polyol 12 according to the amounts specified in Table 4 in a plastic cup (SpeedMixer?) and mixed using a SpeedMixer? (2500 rpm, 120 s). The resulting mixture was heated to 100? C. for 10 min under ambient atmosphere after which the mixing step was repeated. The heating and mixing step was repeated once to obtain a homogeneously dispersed anhydride. The highly viscous to solid mixture was heated a further 40 min to 100? C. under ambient atmosphere, followed by a curing under vacuum at 140? C. overnight (approximately 16 h). The obtained (foamed) network was ground to a fine powder.

TABLE-US-00003 TABLE 3 Epoxide 9 NMEA DBA Equivalent weight Polyol (mmol) (mmol) (mmol) (OH, g/mol) 12a 29.38 (9a) 14.69 44.06 228.74 12b 49.44 (9b) 24.72 74.17 173.47 12c 52.63 (9c) 26.32 78.95 244.57

TABLE-US-00004 TABLE 4 Net- Polyol 12 Dianhydride Dianhydride T.sub.g T.sub.deg, 5% T.sub.press work (g) 13 (mmol) 13 (g) (? C.) (? C.) (? C.) 14aa 2.197 (12a) 4.80 (13a) 2.500 (13a) 106 321 180 14ab 3.687 (12a) 8.06 (13b) 2.500 (13b) 127 287 180 14ac 3.887 (12a) 8.50 (13c) 2.500 (13c) 138 288 180 14ba 1.666 (12b) 4.80 (13a) 2.500 (13a) 89 308 150 14bb 2.796 (12b) 8.06 (13b) 2.500 (13b) 105 278 180 14bc 2.948 (12b) 8.50 (13c) 2.500 (13c) 121 276 180 14ca 2.349 (12c) 4.80 (13a) 2.500 (13a) 102 257 150 14cb 3.942 (12c) 8.06 (13b) 2.500 (13b) 99 244 180 14cc 4.156 (12c) 8.50 (13c) 2.500 (13c) 117 248 180

[0192] To evaluate the materials, their glass transition temperature (T.sub.g) and degradation temperature (T.sub.deg, 5%) were determined via dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively, as detailed in example 2. The resulting values are listed in Table 4.

[0193] All the ground networks could be pressed into a homogeneous and semi-transparent network using a hot press at 4 metric tons for 15-30 min at a temperature above the T.sub.g of the material (T.sub.press, Table 4).

Example 4

[0194] A network according to the present invention is synthesized according to the strategy and experimental procedure detailed in example 3 whereby the dianhydride monomer 13 is replaced with an alternative dianhydride monomer comprising a cyclic or aromatic structure with at least two anhydride groups as substituents, for example pyromellitic dianhydride (PMDA), bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCODA), and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA). Optionally, the polyol 12 can be diluted with a solvent, for example dioxane or N-methyl-2-pyrrolidone (NMP), prior to addition of said dianhydride monomer.

[0195] Networks were obtained by processing the precursors of polyol 12, PMDA or BCODA or NTCDA as dianhydride monomer and optional solvent according to the amounts specified in Table and as detailed in example 3. If NMP is added as solvent, the heating steps under ambient atmosphere of the mixture of polyol, dianhydride monomer, and NMP are performed at 120? C. instead of 100? C. and the heating and mixing step was repeated until a clear solution was obtained.

TABLE-US-00005 TABLE 5 Dianhydride T.sub.g T.sub.deg, 5% T.sub.press Entry Polyol 12 monomer Solvent (? C.) (? C.) (? C.) 1 5.243 g 12a 2.500 g PMDA None 151 262 180 2 4.608 g 12a 2.500 g BCODA 5 mL 85 215 150 NMP 3 4.265 g 12a 2.500 g NTCDA None 42 272 120 4 3.977 g 12b 2.500 g PMDA 2.5 mL 120 237 180 NMP 5 3.495 g 12b 2.500 g BCODA 2.5 mL 49 293 140 dioxane 6 5.606 g 12c 2.500 g PMDA None 117 232 150 7 4.927 g 12c 2.500 g BCODA 2.5 mL 50 254 140 dioxane

[0196] To evaluate the materials, their glass transition temperature (Tg) and degradation temperature (T.sub.deg, 5%) were determined via dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively, as detailed in example 2. The resulting values are listed in Table 5.

[0197] All the ground networks could be pressed into a homogeneous and semi-transparent network using a hot press at 4 metric tons for 15-30 min at a temperature above the T.sub.g of the material (T.sub.press, Table 5).

Example 5

[0198] A network according to the present invention is synthesized according to the strategy and experimental procedure detailed in example 3 whereby the dianhydride monomer 13 is replaced with an alternative monomer comprising at least two pairs of carboxyl groups, for example 1,2,3,4-cyclopentanetetracarboxylic acid (CPTA) and 1,2,3,4-butanetetracarboxylic acid (BTA). Optionally, the polyol 12 can be diluted with a solvent, for example N-methyl-2-pyrrolidone (NMP), prior to addition of said monomer.

[0199] Networks were obtained by using the precursors of polyol 12, CPTA or BTA as replacement of dianhydride monomer 13 and optional solvent according to the amounts specified in Table 6. The compounds were processed as described in detail in example 3 whereby the heating steps under ambient atmosphere were performed at 120? C. instead of 100? C. and increased in length from 10 min to 30 min and from 40 min to 90 min, respectively.

TABLE-US-00006 TABLE 6 Dianhydride T.sub.g T.sub.deg, 5% T.sub.press Entry Polyol 12 monomer Solvent (? C.) (? C.) (? C.) 1 4.646 g 12a 2.500 g CPTA None 115 271 180 2 4.884 g 12a 2.500 g BTA 2.5 mL 74 246 150 NMP

[0200] To evaluate the materials, their glass transition temperature (T.sub.g) and degradation temperature (T.sub.deg, 5%) were determined via dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively, as detailed in example 2. The resulting values are listed in Table 6.

[0201] All the ground networks could be pressed into a homogeneous and semi-transparent network using a hot press at 4 metric tons for 15-30 min at a temperature above the T.sub.g of the material (T.sub.press, Table 6).