SU440378A1 - The method of producing block copolymers - Google Patents

Description

one

The invention relates to methods for producing block copolymers by radical copolymerization in suspension, solution or weight of vinyl and acrylic monomers.

Of all the known methods for producing block copolymers, the greatest interest is the use of "living polymers, because it allows to obtain block copolymers with a predetermined structure of macromolecules.

The most difficult and critical part of the process is the synthesis of a living polymer whose molecules contain peroxide groups at the end or in the middle of the molecular chain.

A known method of producing polymers with terminal peroxide groups by polymerizing vinyl monomers in the presence of monosubstituted diperoxy derivatives of aliphatic diacids.

The resulting living polymer is used as an initiator in the preparation of block copolymers.

Despite obvious advantages over previously known methods, this method has several disadvantages, the most serious of which are the following.

1. The use of insufficiently active monosubstituted di-peroxide derivatives of aliphatic diacids as initiators compels polymerization to be carried out only at high temperatures (60-95 ° C) and even higher temperatures (by 15-

25 ° C higher than indicated) block copolymerization is carried out.

It is known that if the polymerization of some monomers, for example, vinyl chloride, is carried out at such high temperatures, then

polyvinyl chloride is obtained low molecular weight, branched, rapidly decomposing, etc.

2. The use of di-peroxide compounds results in polymers with a terminal peroxide group. When using the latter as an initiator for the preparation of block copolymers along with block copolymers, an equivalent amount of the homopolymer of the second monomer according to the scheme

A-A-A-A-A-A-A-A-O-O-R-b "B -

-. R. - / .- Jo ij

-B B-B + R-O-B B-B-B-B.

The purpose of the invention is to reduce the temperature of block copolymerization and decrease the amount of homopolymers at 30 months.

For this purpose, as a radical polymerization initiator, triperoxide compounds of the general formula are used to produce block copolymers.

 ROOROOROOR,

where R is cyclopentylidene, cyclohexylidene; R - various functional groups, such as

. "Ww -CeKjOC-, CHjCOClCHO C

II

n o

to o

The amount of peroxide used is 0.02-0.5 wt. % of the amount of monomers.

Vinyl chloride, vinylidene chloride, vinyl acetate, alkyl acrylates and alkyl methacrylates, styrene, divinyl and its derivatives are used as comonomers.

The triperexane compounds used as initiators contain three peroxide chains, of which the two extreme ones decompose at a higher rate at low temperatures than the central one.

The amount of peroxide copolymerization taken and its activity is calculated in such a way that, at the "live copolymer" production stage (first stage), the extreme peroxide chains disintegrate completely by the end of the stage. At this stage, a copolymer is obtained whose macromolecules contain in their central part peroxyl chains of the acyl or dialkyl type.

The temperature of the first stage is 15-50 ° C.

In the second stage, the "living polymer of the second monomer or (comonomers)" is grafted, resulting from the breakdown of peroxide chains in the central part of the copolymer macromolecules obtained in the first stage.

The temperature of the second stage is 50-70 ° С.

Block copolymers are obtained as a result of which macromolecules consist of two different parts (blocks), each block having the structure of a homo- or copolymer, for example

АААААААА-ВВВВВВВВ (type 1) AACACCAAACCACCAA-BBDDDBBDB

(type 2) AAAAAAAA-BBDDDBBDBDDBB (type 3)

The block structure is determined by the comonomer loading order. The length of the block (weight fraction) in the copolymer is controlled by the temperature and the amount of monomers loaded in the first and second stages.

Thus, the method makes it possible to obtain at low temperatures a wide range of relatively pure block copolymers with a predetermined structure of macromolecules.

Example 1-3. 800 g of vinyl chloride, 1600 g of aqueous phase containing 0.08% methylcellulose and 0.3% triperoxide (see table) based on the weight of vinyl chloride are loaded into a 4 l autoclave. The polymerization is carried out at 20 ° C until the pressure in the reactor drops by 1 atm from the initial (in examples 2 and 3, the polymerization temperature is 30 ° C).

The polymer obtained is washed from the emulsifier with water, dried at room temperature and used for block copolymerization. The block copolymerization (second stage) is carried out in glass ampoules at 70 ° C in

for 7 hours Methyl methacrylate, acrylic acid or styrene, respectively, are used as the second comonomer. The obtained block copolymer is washed from the homopolymer with an appropriate solvent (benzene,

water and benzene).

The number of components loaded in the second stage, and the output of the corresponding block copolymer are summarized in the table. 5 The subject invention. The method of producing block copolymers by radical copolymerization of monomers of vinyl and acrylic series in the presence of 5 initiator, characterized in that, in order to lower the temperature of block copolymerization and reduce the impurity of homopolymers, three initiation compounds of the general formula ROOROOROOR, where R - cyclopentylidene, cyclohexylidene; n CH, She -; "" Shch:., Nl-) C-CH SOS (CH) G and i, and OOOO