MXPA00010443A - Polymerization process using high-temperature multifunctional initiators. - Google Patents

Abstract

The present invention depicts a process for the preparation of polymers and copolymers from unsaturated ethylenic monomers using peroxidic initiation systems where at least one of them is a cyclic peroxidic initiator derived from ketones and where at least the 20% of total active oxygen, preferably the 60-70%, is attributable to the cyclic initiator. The cyclic peroxidic initiators present the general formula 1-111 wherein: the substituents R1-R8 are equal or different, each of them being independently, a hydrogen atom, a halogen or a selected group of alkyl radicals, linear or branched, cyclic or acyclic, saturated or unsaturated, substituted or not substituted having a number of carbon atoms from 1 to 30; of aromatic hydrocarbon radicals, having a number of carbon atoms from 6 to 13, substituted or not substituted, wherein one or more carbon atoms are replaced by heteroatoms selected from the VA Group of the Elements Periodic Table, of chemical functions as alcohols, alkyl halides, aromatic or aliphatic, substituted or not substituted amines, amides, nitrile and carboxylated functions. The cyclic initiators of formula I-III present a performance in the process of polymeric initiation, higher than its counterparts, this is; aliphatic dialkylketone peroxides and can be compared to the performance of other peroxides commercially known and used at an industrial level. Among the more relevant advantages reached with the use of the cyclic peroxides depicted in the present invention there can be mentioned: high speed of polymerization, high molecular weights of the obtained products and reduction of the reaction by-products, which are attributed to secondary reactions of peroxides during their decomposition.

Description

"POLYMERIZATION PROCESS USING MULTIFUNCTIONAL HIGH TEMPERATURE INITIATORS" BACKGROUND OF THE INVENTION In general, in polymerizations and radical copolymerizations, an increase in the polymerization rate may occur by an increase in the concentration of the initiator and / or an increase in the reaction temperature. Such an increase results in a decrease in the molecular weight of the synthesized polymers and therefore a variation in the final properties of the products. For this reason, in recent years there has been great interest in polymerization processes that allow not only increase the speed of polymerization but at the same time allow to maintain, and even increase, the molecular weight of the polymers produced, reason why which the multifunctional initiators have received great attention since they allow to solve the aforementioned problems to a great extent. Prior to the present invention, a large number of patents have been reported which describe polymerization processes of styrene in one or several stages using mixtures of two or more initiators, which results in a synergism between the initiators employed leading to high polymerization rates, without detriment to molecular weights. For example, in the U.S. Pat. No. 2,656,334 and 2,907,756, the polymerization in each of the stages is isothermally conducted, however, the great disadvantage of these processes are the extremely long polymerization times, which make these processes little applicable on an industrial scale. In the Canadian patent CA Pat. 892,672, Squire and Gammon describe a process for the polymerization of vinic monomers in the presence of one or more radical initiators by establishing a temperature program throughout the reaction. In said document it is established that the molecular weight can be increased by the addition of small amounts of a crosslinking agent such as divinylbenzene; however, no evidence is reported where it is demonstrated that the increase in molecular weight of the polymers can be attributed to the use of polyfunctional initiators. Mace in the U.S. Pat. No. 3,817,965 describes a process for the emulsion polymerization of vinyl monomers in order to obtain high molecular weight products. In this process, the temperature of the suspension increases rapidly from 95 ° C to 100-150 ° C and then increases linearly until reaching, in a second stage, a temperature range of 120-160 ° C. Under these conditions the molecular weight can be controlled essentially by an adjustment in the increase of the temperature. In these cases, the radical initiators used are of the peroxidic type, with mixtures of them being used in many cases, where at least one of the initiators has more than one peroxidic bond in its structure. On the other hand, several peroxides from ketones have been described in the literature as radical initiators for the polymerization of unsaturated ethylenic monomers. For example, the U.S. Pat. No. 3,149,126 reports some peroxides derived from the interaction of the 1,3- and 1,4-diketones, which can be used as catalysts in polymerization reactions and cross-linking of polymers. The U.S. Pat. No. 3,003,000 describes a method for obtaining multifunctional peroxides, which are constituted by mixture of linear and cyclic peroxides in a very low proportion as a consequence of secondary reactions. Said mixtures have been efficiently used as reaction catalysts for diesel combustion. The German patent DE Pat. 21 32 315 reports on trimetric peroxides of cycloketone and in particular tricycloalkylideneperoxides of which it is said that they can be used in polymerization but the patent describes fundamentally the most relevant aspects on the synthesis of these structures. Despite the efforts made in the search and use of new initiators for the optimization of polymerization conditions and processes, there still persists the need in the art of polymerization initiators, to find peroxides that provide a good performance and that are profitable and applicable at industrial level. This and other objectives will be presented in the summary and will be detailed in the description of the present invention.

DESCRD7TION OF THE INVENTION The present invention describes the use of multifunctional cyclic peroxidic initiators of general formula I-III, as initiators of the polymerization and radical copolymerization of unsaturated monomers. The cyclic peroxide initiators correspond to the general formulas I-III wherein: the substituents R * -R8 are the same or different, each of which is independently a hydrogen atom, a halogen or a selected group of alkyl radicals, linear or branched, cyclic or acyclic, saturated or unsaturated, substituted or unsubstituted, with number of carbon atoms from 1 to 30; of aromatic hydrocarbon radicals, with number of carbon atoms of 6 to 13, substituted or unsubstituted, where one or more carbon atoms is replaced by heteroatoms selected from Group VA of the Periodic Table of the Elements, of idroxyl functional groups, halogens , amines, saturated groups, among others; without this being exclusive for any other chemical function, which may be susceptible to protection in the formation stage of the corresponding peroxide.

The cyclic peroxide initiators of formula I-III described in the present invention, unlike other similar or similar ones reported in other patents, were prepared by methods perfected by Eyler G.N .; Cañizo AL; Alvarez E.E .; and Cafferata L.F.R .; Tetrahedr Letts. 34, 1745-46 (1993), C.M. Mateo, G.N. Eyler, E.E. Alvarez and AL Cañizo; Information Technology, Vol 9, No. 2 (1998) from those already described in the U.S. patent. Patent No. 3,003,000; the article by Milas, N.A. and Golubovic, To J. Am. Chem. Soc; 81, p. 5824-26 (1959) and Story in the American patents No. 3,925,421 and 3,960,897, respectively. Ketones that can be used for the synthesis of the cyclic peroxide initiators of formula I-III include, for example; acetone, acetophenone, methyl-n-amyl ketone, ethylamyl ketone, dimethyl ketone, diethyl ketone, dipropyl ketone, methyl ethyl ketone, ethyl butyl ketone, ethyl propyl ketone, methyl isoamyl ketone, methyl ethyl ketone, methyhexyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, methyl propyl ketone, methyl t-butyl ketone, isobutyl heptyl ketone, diisobutyl ketone, fluorenone , norbornendione, 2,4-pentanedione, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, 3,5-octanedione, 5-methyl-2,4-hexanedione, 2,6-dimethyl-3 , 5-heptanedione, 2,4-octanedione, 5,5-dimethyl-2,4-hexanedione, 6-methyl-2,4-heptanedione, 1-phenyl-1, 3-butanedione, 1-phenyl-1, 3 -pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-2,4-pentanedione, methylbenzyl ketone, phenyl methyl ketone, phenylethyl ketone, methylchloromethyl ketone, methyl bromomethyl ketone, and products of the mixtures of any of the aforementioned ketones. Among the cyclic ketones which can be used for the synthesis of the cyclic peroxides I-rp, mention may be made of: cyclopentanone, 2-methylcyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, t-butyl cyclohexanone, -t-butylamylcyanohexanone, 4-methoxycyclohexanone, 3,3,5-trimethylcyclohexanone, 2-chlorocyclohexanone, cycloheptanone, cyclooctanone, 2-chlorocyclooctanone, cyclononanone, cyclodecanone, cycloundecanone, cyclododecanone, cyclotridecanone, cyclotetradecanone, cyclopentadecanone, cyclohexadecanone, cycloheptadecanone, cyclooctadecanone , cyclononadecanone, and cycloeicosanone and any ketone with the appropriate R groups that allow the synthesis of cyclic peroxides such as those mentioned in the present invention.

The cyclic peroxides described in the present invention can be used as efficient polymerization initiators and, in particular, for the preparation of polystyrene homopolymers and copolymers, poly (methyl methacrylate), poly (butyl acrylate), poly (butyl methacrylate) ), poly (acrylonitrile) and block and / or grafted copolymers, including polybutadiene-g-polystyrene (HIPS), derivatives of the aforementioned polymers. In the particular case of the polymerization of styrene, when the cyclic peroxides described in the present invention are employed as polymerization initiators, high polymerization rates, high conversions and high molecular weights can be obtained simultaneously. In turn, the residual monomer content and the content of dimers and trimers are substantially reduced, which cause yellowing in the final products if their content is greater than 2%. It should be mentioned that such results are obtained indistinctly if the polymerization is carried out by a mass process, solution, and / or suspension. In the present invention the polymerizations are carried out by conventional processes and the amount of initiator can be varied according to the structural differences of each initiator employed, its thermal stability, the polymerization temperature and the type of monomer. The polymerization temperature in most cases can vary in the range of 70 to 250 ° C and preferably in the range of 80-200 ° C and more preferably in the range of 110 to 150 ° C. Below 70 ° C, in most cases, the polymerization takes place only at very long intervals of time due to the extremely low decomposition rate. At temperatures of the order of 180-200 ° C, the polymerization takes place at a high speed but with evident detriment in the molecular weights of the materials and hence their properties. At temperatures close to 250 ° C, the decomposition of the cyclic peroxides is almost instantaneous, so one can not speak of a polymerization induced by the peroxides of formula I-III. The reactions can be carried out by a process in stages or with temperature-time ramps, with initial temperatures preferably of 90 ° C and final 150-180 ° C, depending on the initiator used and the polymerization process chosen. An important condition for the polymerization to take place is that at least 20% of the total active oxygen contained in the peroxides is attributed to the multifunctional cyclic peroxides described in the present invention. Preferentially 70% of the total active oxygen in the peroxide composition used for the polymerizations and copolymerizations should be attributed to the multi-national cyclic peroxide. The advantages provided both to the polymerization processes and to the final products obtained are shown below in comparative examples.

The multifunctional cyclic peroxides according to the present invention can be used in the polymerization of a large variety of monomers, such as olefinic monomers or unsaturated, substituted or unsubstituted ethylenic monomers, for example; acrylic and methacrylic monomers, acrylonitrile, methacrylonitrile, acrylamide, styrene, α-methylstyrene, p-methylstyrene and halogenated styrenes, divinylbenzene, ethylene, butadiene, isoprene, chloroprene, vinylacetate, vinylpropionate, isobutene, 4-methylpentene. These are non-exclusive examples of any other monomer or mixtures of monomers that can be radically polymerized.

Finally, the polymerization process of the present invention can be used for the introduction of functional groups in the polymer chains. This can be achieved by using the cyclic peroxides of formula I-III which have functional groups (R ^ R8) in their structure, among them: hydroxyls, halogens, amines, saturated groups, among others; without this being exclusive for any other chemical function, which may be susceptible to protection in the formation stage of the corresponding peroxide.

The present invention is illustrated with different examples, which are illustrative but in no way limiting.

EXPERIMENTAL PART All the polymerizations were carried out in clean and dry glass tubes in which variable amounts of the cyclic initiator of formula I-III (0.005-0.02 M) and monomer were added, which were homogenized by stirring. Subsequently, the tubes were degassed by cooling-heating cycles between room temperature and liquid nitrogen temperature. The tubes were sealed under vacuum and immersed in an oil bath at constant temperature, comprised in the range of 70-250 ° C and preferably in the range of 80-200 ° C and more preferably in the range of 110-150. ° C depending, fundamentally, on the initiator employed. Kinetic monitoring was carried out at 15, 30, 45, 60, 90, 180, 240 and 360 minutes. After the pre-established times the products were isolated and analyzed. A blank experiment conducted under the same experimental conditions gave different results to those in which non-zero amounts of cyclic peroxides I-III were used in the formulations. From the supernatants the amount of residual dimers and trimers was determined by G.C-M.S. chromatography. Likewise, the residual monomer content was determined by gas chromatography coupled with detector for Head Space using toluene as internal standard. The molecular weight of the polymers was determined by gel permeation chromatography (GPC) using polystyrene standards. The values of Mw for all the products analyzed fall within the range of application of industrial processing processes such as extrusion, injection molding, etc., while the polymerization rate can be increased by a factor of 4 with respect to a polymerization in white.

EXAMPLE 1.- Mass polymerization of styrene using acetone triperoxide (TPA) as initiator.

The TPA corresponds to the cyclic peroxide initiators of formula I described in the present invention where R ^ R6 = CH3. Table 1 shows the results of the polymerization of styrene in the presence of TPA as a radical cyclic initiator at 150 ° C. It is observed that there is indeed initiation by the cyclic initiator, reaching conversions of the order of 97% and molecular weights of 2.21 x 105 g / mol. If the polymerization temperature is changed to 180 ° C, so that the half-life of the initiator is one hour, the conversions and molecular weights are of the order of 99% and 0.70 x 105 g / mol, respectively.

Table 1.- Characteristics and experimental conditions of the polystyrenes obtained at 150 ° C, using TPA as initiator.

Time Conversion Mn x 10"5 Mw x 10" 5 Experiment I (min.) (%) (G / mol) (g / mol) 1 15 10.79 1.35 2.48 1.8 2 30 25.84 1.21 2.21 1.8 3 45 44.33 1.07 2.01 1.9 4 60 53.82 1.22 2.11 1.7 5 90 87.40 1.06 2.20 2.1 6 180 95.00 0.46 1.00 2.4 7 240 96.00 0.93 2.07 2.2 8 360 96.17 0.91 1.96 2.1 EXAMPLE 2.- Mass polymerization of styrene using cyclohexanone diperoxide (DPCU) as initiator.

Polymerization of the styrene initiated with DPCH was carried out at 150 ° C (n-1.43 hours). Table 2 shows the results of said polymerization as well as the characteristics of the polymers obtained. These results show that after 6 hours of polymerization it is possible to reach conversion values and molecular weights comparable to those of Example 1. On the other hand, the evolution of the conversion and molecular weight has a similar behavior to the previous one.

Table 2.- Characteristics and experimental conditions of the polystyrenes obtained at 150 ° C, using DPCH as initiator, [DPCH] = 0.01M.

Conversion time Mn x 10_ Mw x 10"Experiment (min.) (G / mol) (g / mol) 1 15 12.09 1.56 2.90 1.9 2 30 25.14 1.40 2.66 1.9 3 45 36.02 1.36 2.58 1.9 4 60 44.35 1.41 2.70 1.9 5 90 59.41 1.47 2.63 1.8 6 180 84.83 1.22 2.14 1.8 7 240 91.44 1.27 2.52 2.0 8 360 96.17 1.48 2.69 1.8 EXAMPLE 3.- Mass polymerization of styrene using diethyl ketone triperix (TPDEQ as initiator.

The TPDEC corresponds to the formula II described in the present invention where R'-R6 = C2H5. Table 3 reports the characteristics of the polymers obtained from TPDEC at different temperatures.

Table 3.- Characteristics of the polystyrenes obtained at different temperatures using TPDEC as initiator. [TPDEC] = 0.01M, t. of polymerization = 6 hours Conversion Mn x 10"5 Mw x 10, -5 Temperature ro / I = Mw Mn (g / mol) (g / mol) (° C) 120 92.0 2.50 5.32 2.1 130 98.2 1.61 3.24 2.0 For this particular initiator, regardless of the polymerization temperature, the initiation capacity is much higher compared to the previous examples. Likewise, it is observed that although the concentration of initiator is low at 6 hours of polymerization (16.7% and 4% of initiator for 130 and 120 ° C respectively), the conversion values reached are high. With regard to molecular weights, the possibility of obtaining PS with such a large variation of molecular weights by means of a simple variation of the polymerization temperature, broadens the spectrum of applications of the synthesized materials, being in all cases acceptable from the commercial point of view.

EXAMPLE 4.- Mass polymerization of styrene using diethyl ketone triper-oxide (TPDEQ as initiator at different temperatures and concentration of cyclic initiator.

The TPDEC primer was evaluated at two different concentration levels (0.01 and 0.02 M) at 130 and 120 ° C respectively. Table 4 reports the characteristics of the materials obtained under these conditions.

Table 4.- Characteristics of polystyrenes obtained from TPDEC at different temperatures and initiator concentrations T = 130 ° C Conversion Conversion Mn x 10'5 Mw x 10'5 of initiator I = Mw / Mn (%) (g / mol) (g / mol) (mol / L) 0. 01 98.0 1.61 3.24 2.0 0.02 99.0 1.21 2.30 1.9 T = 120 ° C Conversion Conversion Mn x 10"5 Mw x 10" 5 of initiator I = Mw / Mn (%) (g / mol) (g / mol) (mol / L) 0.01 92.0 2.50 5.32 2.1 0.02 99.0 1.74 3.16 1.8 Regarding the polymerization carried out at 120 ° C, an increase in the concentration of initiator causes a substantial increase in the conversion according to the data 13 reported in Table 4. Likewise, the molecular weights decrease as a consequence of a decrease in the kinetic chain length caused in turn by an increase in the concentration of radicals. However, even when the molecular weights have decreased, they are substantially higher than those obtained by initiation with a monofunctional initiator (Mw (BPO, 6hs) = 9.0 x 104 g / mol) under the same experimental conditions and the values fall within of commercial acceptance limits.

EXAMPLE 5.- Mass polymerization of styrene using diperoxide depinacolone (DPP) as initiator.

The DPP corresponds to the general formula I described in the present invention where RI = R3 = CH3 and R2 = R4 = -C (CH3) 3 The results of said polymerization are presented in Table 5.

Table 5.- Characteristics and experimental conditions of the polystyrenes obtained at 150 ° C, using DPP as initiator, [DPP] = 0.01M.

Conversion time Mn x 10- Mw x 10"5 Experiment (min.) (G / mol) (g / mol) 1 15 11.0 0.99 1.78 1.8 2 30 25.2 1.07 1.80 1.7 3 45 38.8 1.08 1.88 1.7 4 60 62.6 1.09 1.89 1.7 5 90 81.9 1.24 2.35 1.9 6 180 95.7 1.02 1.86 1.8 7 240 99.4 1.16 2.36 2.0 8 360 99.9 1.08 2.21 2.0 14 After 6 hours of polymerization, the residual monomer was analyzed and a concentration of 230 ppm was determined. If it is taken into account that with some initiators currently employed in the industry, the concentration of residual monomer is of the order of 300-450 ppm, the advantage offered by this initiator in the polymerization of styrene is appreciable. On the other hand, the high conversion values and therefore high polymerization rates, together with the high molecular weights presented by the polymers obtained, demonstrate the excellent performance on the part of this initiator.

EXAMPLE 6.- Mass polymerization of methyl methacrylate using diethyl ketone trioxide (TPDEQ as initiator.

The polymerization of methyl methacrylate (MMA) was carried out using a TPDEC concentration of 0.01M. After 6 hours of polymerization, a conversion of 99.9% and weight average molecular weight (Mw) of the order of 310.00 g / mol was determined. As expected, the polymerization rate is higher, under the same experimental conditions, than in the case of polymerization of styrene, an order of magnitude higher. The evolution of the molecular weight with the polymerization time confirms the sequential decomposition of the initiator.

EXAMPLE 7.- Mass polymerization of styrene using combined initiation systems In the case of TPDEC as initiator of styrene polymerization, different initiation systems were evaluated at different experimental conditions. For this purpose, different low temperature initiators were used, such as benzoyl peroxide (BPO), tert-butylperoxy-2-eti-Hexanoate (IB-1) and l, l-bis [tert-butylperoxy] cyclohexane (IB-2). Table 7 shows the three different initiation systems, which were evaluated in a two-stage polymerization process, under the conditions 15 experimental ones that are detailed. In all cases, the total concentration of initiators is 0.01M and the TPDEC concentration is 0.005M.

Table 7.- Binary initiation systems: experimental conditions and characteristics of the synthesized materials.

EXAMPLE 8. ~ Mass polymerization of styrene using tetrafunctional initiators.

The styrene polymerization was carried out under the same experimental conditions as those described for example 2, using in this case in particular a tetrafunction initiator of general formula III according to that described in the present invention where the substituents R! -R8 = CH3 In this case, the results of the polymerization were very encouraging since the conversion values were 99.9% after 4.5 hours of polymerization and the molecular weights Mw in the range of 300,000-520,000 g / mol, the latter depending on the concentration of initiator used (0.01M and 0.005M respectively). 17

Claims (10)

CLAIMS What we claim is:

1. - A process for the polymerization and / or radical copolymerization of unsaturated monomers, where the initiation system is formed by at least one peroxidic initiator where, under suitable experimental conditions, said peroxide can be decomposed and where at least 20% of the total content of active oxygen is attributable to a cyclic peroxide from ketones, with formulas I-III. p III wherein: the substituents R! -R8 are the same or different, each of which is independently, a hydrogen atom, a halogen or a selected group of alkyl radicals, linear or branched, cyclic or acyclic, saturated or unsaturated, substituted or unsubstituted, with number of carbon atoms from 1 to 30; of aromatic hydrocarbon radicals, with number of carbon atoms of 6 to 13, substituted or unsubstituted, where one or more carbon atoms is replaced by heteroatoms selected from Group VA of the Periodic Table of the Elements, of chemical functions such as alcohols, alkyl halides, substituted or unsubstituted, aromatic or aliphatic amines, amides, nitrite and carboxylated functions. 18

2. - A process according to claim 1, wherein the polymerization can be carried out in a process in stages or by temperature-time ramps.

3. - A process according to claim 1, wherein the polymerization can be carried out at temperatures comprised between 70-250 ° C, and the total peroxide content is 0.001-30% by weight based on the weight of polymer and / or copolymer .

4. - A process according to claim 1 wherein the cyclic peroxides can be combined with any other mono- or polyfunctional peroxide initiator or initiator of the azo type or radical initiators that generate by decomposition, radicals centered on the carbon or on another heteroatom and at least the 20% of the total active oxygen content is attributable to the cyclic peroxide from ketones of formula I-III.

5. - A process according to claim 1 wherein the cyclic peroxides can be obtained from ketones such as acetone, acetophenone, methyl n-ammonetone, ethylbutyl ketone, ethylpropyl ketone, methyl isoamyl ketone, methylheptyl ketone, methylhexyl ketone, ethylamyl ketone. dimethyl ketone, diethyl ketone, dipropyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, methyl propyl ketone, methyl t-butyl ketone, isobutyl heptyl ketone, dibutylbutylketone, fluorenone, norbornendione, 2,4-pentanedione, 2,4-hexanedione, 2,4-heptanedione, 3 , 5-heptanedione, 3,5-octanedione, 5-methyl-2,4-hexanedione, 2,6-dimethyl-3,5-heptanedione, 2,4-octanedione, 5,5-dimethyl-2,4-hexanedione ,

6-methyl-2,4-heptanedione, l-phenyl-1,3-butanedione, 1-phenyl-1,3-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-2,4- pentanedione, methylbenzyl ketone, phenyl methyl ketone, phenylethyl ketone, methyl chloromethyl ketone, methyl bromomethyl ketone, and products of the mixtures of any of the aforementioned ketones, by the synthesis method described herein.

7. - A process according to claim 1 wherein the cyclic peroxides can be obtained from cyclic ketones such as: cyclopentanone, 2-methylcyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, t-butylcyclohexanone , 4-t-butylamylcyclohexanone, 4-methoxycyclohexanone, 3,3,5-trimethylcyclohexanone, 2-chlorocyclohexanone, cycloheptanone, 19-cyclooctanone, 2-chlorocyclooctanone, cyclononanone, cyclodecanone, cycloundecanone, cyclododecanone, cyclotridecanone, cyclotetradecanone, cyclopentadecanone, cyclohexadecanone, cycloheptadecanone, cyclooctadecanone, cyclononadecanone, and cycloeicosanone and any ketone with the appropriate R groups that allow the synthesis of cyclic peroxides mentioned in claim 1, according to the synthesis method described herein.

8. - A process according to claim 1 wherein at least one of the unsaturated monomers is selected from any styrenic, acrylic, methacrylic, olefinic and diene monomers, substituted or unsubstituted.

9. - A process according to claim 1 which can be carried out by mass, solution, suspension or emulsion techniques.

10. - A process according to claim 1 which can be carried out by a mass-extrusion process, reactive processing or combinations of processes. twenty