CS231235B1 - Process for the preparation of low molecular weight polymers of styrene or methyl methacrylate or their copolymers - Google Patents

Abstract

A method for preparing low molecular weight polymers of styrene or methyl methacrylate or their mutual copolymers by radical polymerization of the respective monomers, in which tetraalkylthiuram disulfides of the general formula R /S— S R'-^ ^-S S ^R \R' are used as radical initiators and at the same time as chain length regulators, where R is CH3, C^, C,^, and R' is CH3, CjjHj, C3H7, C4H9 or R and H' together form -/CH^/^-, -/ch2/4 - —V preferably tetramethylthiuram disulfide at a concentration of 3 to 12 g, preferably 6 to 9 g per 100 cm } of the polymerization batch, the polymerization being carried out at a temperature of 50 to 140 °C for 8 to 16 hours.

Description

231235 2

Low molecular weight polymers based on vinyl monomers can be prepared by ionic, cationic or radical polymerization. AND

Anionic polymerization, in addition to some of the advantages that the polymerization process can be conducted without termination, until the monomer is completely converted, that the length of the polymer chain can be comfortably controlled and that the polymer produced has a molecular weight loss and a number of disadvantages. which result from high demands on experimental technique and on the purity of chemicals, since any moisture or impurity will pre-tether the living ends.

Cationic polymerization is one of the less advantageous forms of oligomer preparation since it is often accompanied by secondary reactions, due to which the structure and thus the properties of the resulting oligomers are altered.

Radical polymerization is a very simple preparation process and has several advantages over ionic polymerization, as suggested by a number of pathogenic polystyrene-protecting patents. Currently, low molecular weight polymers are prepared by free radical polymerization by initiating a vinyl monomer with a peroxide or azo initiator and obtaining the desired molecular weight of the polymer using a molecular weight regulator. Oligomeric polystyrenes are usually prepared using conventional, highly substituted peroxidic initiators such as debenzoyl peroxide, potassium peroxide sulfate, diisopropyl peroxide dicarbonate at high concentrations of 1-106. (ditzopropyl-xantogene disulfide and the like).

The essence of the preparation of low molecular weight polymers of old or methyl methacrylate or their copolymers by radical polymerization of adherent monomers of the present invention is to use tetraalkylthiuram disulfides of the general formula S- as the radical initiator and at the same time the chain length regulator.

R 1 'wherein R is CH 2 C 1, R 2 is R 2 is CH 3, C 8 H 11, C 1 H 4, C 8 H 11, or R 1 and R 1 are taken together to form 3 (tetramethylthiuram disulfide). from about 12 g to about 6 g to about 100 gPolymerization feed, wherein the polymerization is carried out at 50-140 ° C for about 8-16 hours. The advantage of the present invention over the commonly used methods is that the initiator simultaneously coexists as a molecular weight regulator. By choosing the polymerization temperature and the initiator concentration, the rapid polymerization and molecular weight of the polymers can be controlled in a wide range. the more advantageous advantage of the proposed method is that the low molecular weight polymers prepared have chain groups incorporated into the chain ends which can be used for the reaction.

Polymeric initiators. Nature of alkyl monomers. are tetraalkylthiuram disulfides with the same or roediel groups as affecting. solubility of tetraalkylthiuram disulfides 3 231235

The polymerization can be carried out in a block suspension. or in a solution of concentrate of alkylthiursuadi sulphide, preferably with tetramethylthiuram disulphide, from 3 g per 100 µl to 12 g per 100 µm polymerization feed. At lower initiator concentrations, polymers with a molecular weight above 10,000 are formed. The polymerization time depends mainly on the use of the polymerization temperature. Example 1

Styrene-free stabilizer was polymerized in the presence of 4 g of tetramethylthiuramdi sulphide per 100 cm 2 of solution, at 56 ° C for 3.5 hours in a nitrogen atmosphere. Conversion was 3.64%, molecular weight of polystyrene 3n - 5,900, the content of functional groups on the single molecule f - 1.54. The polymer precipitates upon polymerization with methanol. It is filtered off and dried under vacuum. Example 2

The stabilizer-free styrene is polymerized in a block in the presence of 9 g of tetramethylthiuram disulfide per 100 cm 2 of solution. The polymerization time was 9 hours, the temperature was 75.3 ° C, the atmosphere Ng. The polymer was precipitated with methanol, filtered off and dried in the lid. Conversion of 43.11%, molecular weight Hn ~ 3,660, number of functional groups per macromolecule / polymer functionality / f = 1.48.

Example3

Styrene without stabilizer is polymerized in a block in the presence of 6.2 g of tetramethylthiuram disulfide per 100 cm 2 of solution. Polymerization time 5 hours, temperature 90 ° C, atmosphere Kg. The polymer was precipitated with methanol, filtered off and dried in vacuo. Conversion 54.80%, 3n = 4,200, functionality f = 2.05. Example 4

Styrene without stabilizer is polymerized in a block in the presence of 11 g of tetramethylthiuram disulfide per 100 cm 2 of solution. Polymerization time 3 hours 5 minutes, temperature 100 ° C, Hg atmosphere. The polymer is precipitated with methanol, filtered off and dried under vacuum. Conversion 53.56%, 3n = 2,100, functionality f = 1.46. Example 5

Styrene without stabilizer is polymerized in a block in the presence of 11 g of tetramethylthiuram disulfide per 100 cuP of solution, polymerization time of 10 hours at 80 ° C, post-polymerization for 5 hours at 100 ° C. The polymer is precipitated with methanol, filtered off and dried under vacuum. Conversion 72%, Mn = 2 840, functionality f = 1.77. Example 6

The stabilized styrene is polymerized in a block in the presence of 11 g of tetramethylthiuram disulfide per 100 cm 2 of solution. Polymerization time at 80 ° C for 10 hours and 5 hour polymerization at 20 ° C. The polymer was isolated by evaporation of the monomer in vacuo after addition of hydroquinone. Conversion 93.62%, ffln = 3,200, functionality f = 2.08. The polystyrenes prepared had glass transition temperatures Tg of 70-76 ° C and flow temperatures Tt = 90 ° C. 231235 4 Example 7

Styrene-free stabilizer is polymerized in a benzene solution, a volume fraction of 0.8 in the presence of 3.288 g of tetramethylthiuram disulfide per 100 cm 2 solution at 75 ° C.

After 4 hours of polymerization, a yield of 11.7% (polymer) was obtained and isolated by methanolefin. Bn = 3,700,% S = 1.51, 0.87 functionality. Polydispersity coefficient R = 1.85.

Example8

Styrene-free stabilizer is polymerized in a benzene solution, a 0.4 volume fraction of the mono in the presence of 3.288 g of tetramethylthiuram disulfide per 100 cm 2 solution at 75 ° C.

The polymer is isolated by methanol precipitation. After 4 hours of polymerization, the conversion was 5.2%,

Bn = 2,300,% S = 1.48, functionality f = 0.53. Polydispersity coefficient R = 1.45. Example 9

Styrene is polymerized in chloroform solution, monomer volume fraction 0.5, tetramethylthiuram disulfide concentration 9 g per 100 cnP solution, T = 90 ° C, in sealed ampoules.

After 6 hours of polymerization, a 26% conversion is achieved. Example -

Methyl methacrylate is polymerized in a block at 90 ° C in an N9 atmosphere. Concentration of tetramethylthiuram disulfide 1 g per 100 cm of solution. The conversion was determined by isolating the polymer by methanol precipitation, filtration and drying. The conversion of 50% was achieved after 310 minutes of polymerization. The polymer had Bn = 25,040. Example 11

Methyl methacrylate is polymerized under the same conditions as in Example 10, but at 95 ° C. 50% conversion was achieved after 200 minutes of polymerization. The polymer had a molecular weight of Mn = 15,000. Example 12

The polymerization of methyl methacrylate is carried out in a pressure vessel at T05 ° C in a Ng atmosphere. Concentration of tetramethylthiuram disulfide 1 g per 100 cm 2 polymerization batch. The conversion was determined as in Example 10. After a 115-minute polymerization, the conversion was 50%. The polymer had Mn = 14,400. Example 13

The polymerization of methyl methacrylate is carried out as in Example 12, but at 115 ° C.

After 60 minutes of polymerization, 50% conversion was achieved. Number average molecular weight of polymethyl methacrylate Bn = 12,300. * Example 14

To prepare the styrene copolymer with methyl methacrylate, 101.6 cm @ 3 (mol) of styrene, 106 cm @ -1 (mol) of methyl methacrylate and 2 g of TMTD are used. The copolymerization is carried out in sealed cells in an N 2 atmosphere at 115 ° C. The conversion increased linearly with time. After 30 min, the conversion was 34%. The average numerical molar mass determined by GFC is about 14,000. The molar ratio of styrene to MMA in the copolymer was [ST / MMA] = 1: 0.88.

Claims (1)

SUBJECT KNOWS THE FIND Process for the preparation of low molecular weight polymers of styrene or methyl methacrylate or copolymers thereof by radical polymerization of the respective monomers, characterized in that tetraalkylthiuram disulfides of the general formula wherein R is CH 3, C 8 H 8, C? R is CH ^, ΟΟΗΗ, C ^ HH ^, GgH ^, CgH ^ or Together, E and fi 'form - (CH 2) -, - (CH 2) - preferably tetramethylthiuram disulfide at a concentration of 3 to 12 g, preferably 6 to 9 g per 100 µm of polymerization batch, the polymerization being carried out at a temperature of 50 to 140 ° C for 8 to 16 hours.