Polymers based on block copolymers

Details Polymers based on block copolymers Polymers based on block copolymers

1997-09-12

2000-07-11

Berman, Susan W.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Compositions to be polymerized by wave energy wherein said...

522 39, 522 42, 522 36, 522904, 522135, 522136, 522137, 522142, 522144, 522148, 351159, 351160R, 351160H, 525 90, 525 92C, G02C 702, G02C 704, C08F 250, C08F28700

Patent

active

060874120

DESCRIPTION:

BRIEF SUMMARY
The invention relates to novel polymers based on segmented copolymers, for example block copolymers, that are suitable especially for the production of mouldings, and also to mouldings comprising such polymers, and to the use of the polymers in the production of mouldings and to methods of producing the polymers and the mouldings. Preferred mouldings are ophthalmic lenses, especially contact lenses. The polymers are distinguished from known polymers inter alia by the fact that they contain radicals of photo-initiators incorporated at the interfaces of the blocks. The coupling of the blocks is carried out in a photochemical reaction that allows the segment length of the terminal or pendant polymer blocks being grown on to be substantially controlled. According to the invention a segmented copolymer is to be understood as being a block copolymer, graft copolymer, especially a comb copolymer or star copolymer.
The segmented copolymers according to the invention correspond to the general formula I ##STR2## wherein Macro is an m-valent radical of a macromer from which the number m of groups R.sub.x --H has been removed, or --S-- wherein R.sub.N is hydrogen copolymerisable vinyl monomer by replacing the vinyl double bond by a single bond, suitable to act as a polymerisation chain-reaction terminator, and
The segmented copolymers of formula I according to the invention may be built up from the following constituents: other than a bond, secondly a photoinitiator of formula B photoinitiator that forms the less reactive free radical on cleavage of the photoinitiator, and thirdly a vinyl monomer incorporated as component "A" into the segmented copolymer, wherein A is as defined above.
The macromer of formula A suitable according to the invention has a number m of groups --R.sub.X H, which groups are hydroxy groups (including those that are a component of a carboxy group --COOH), amino groups or lower alkylamino groups (including those that are a component of an amide group --CONR.sub.N) or mercapto groups. Those groups are co-reactive with the isocyanate group of the photoinitiator of formula B. A macromer of formula A is suitably reacted with m mol equivalents of the photoinitiator of formula B to form a macromer of formula (C) ##STR3##
The macromer of formula C so formed, which contains m photoinitiators of formula B bonded via a bridge --O--CO--NH--, --CO--NH--, --NR.sub.N --CO--NH--, --CO--NR.sub.N --CO--NH-- or --S--CO--NH--, is reacted in a further step with p mol equivalents of a vinyl monomer incorporated as component "A" into the copolymer of formula I. Chain-reaction termination is effected, for example, by the less reactive free radical of the photoinitiator R.sub.aa of formula B or by other suitable chain-reaction terminators present in the reaction mixture under the reaction conditions, such as H free radicals or OH free radicals or free radicals formed from solvents. The symbol R.sub.a is preferably the component R.sub.aa of the photoinitiator of formula B.
The definition "bond" for R.sub.x is applicable only in the case where an OH group in the macromer is present as a component of a COOH group. A COOH group reacts with an isocyanate group with the removal of CO.sub.2 and with the formation of a bond "--CO--NH--". Only in that case is R.sub.x a bond in the reaction product, but not in a starting material containing the group "R.sub.x --H".
The index p is preferably a number from 5 to 200, especially a number from 10 to 100.
The index m is preferably a number from 2 to 15, especially a number from 2 to 5.
The groups bonded to the macromer of formula A, of which, depending on the meaning of the index m, there may be from 1 to 100, are either terminal or pendant, or terminal and pendant.
In an especially preferred embodiment, the macromer of formula A has two terminal groups R.sub.x H. A segmented copolymer of formula I according to the invention formed therefrom, that is to say a block copolymer of formula I, is also especially preferred and is referred to in this invention as a tri-block copolymer: the

REFERENCES:
patent: 4977293 (1990-12-01), Hatton et al.
patent: 5070170 (1991-12-01), Robertson et al.
patent: 5334681 (1994-08-01), Mueller et al.
patent: 5371147 (1994-12-01), Spinelli et al.
patent: 5527925 (1996-06-01), Chabrecek et al.
patent: 5532112 (1996-07-01), Kohler et al.
patent: 5612389 (1997-03-01), Chabrecek et al.

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