Copolymers of 4-vinyl:phthalic acid, anhydride or ester(s) - are useful as components of polymer alloys

The use of copolymers (I) contg. 0.1-99.9 wt% 4-vinylphthalic anhydride, 4-vinyl-phthalic acid and/or dialkyl 4-vinylphthalate ester (II) and 99.9-0.1 wt% vinyl and/or diene comonomer(s) (III) as components of polymer alloys is claimed. ADVANTAGE - (I) have a desirable combination of properties as components of polymer alloys, e.g. markedly better heat distortion temp. than corresp. styrene homopolymers, together with the possibility of reactive phase coupling (via acid or anhydride gps.) (I) are therefore useful as compatibilisers in polymer alloys and for the prodn. of polymeric networks; copolymers contg. more than 50 wt% 4-vinylphthalic acid units are soluble in aq. alkali and are therefore also useful for the prodn. of resist materials. In an example, 4-Vinylphthalic acid was prepd. by bromination of phthalic acid with bromine in aq. NaOH soln., followed by reaction with ethylene for 16 hrs. at 100 deg. C and 40 bar in the presence of Et3N, Pd(OAc)2, tri-o-tolyl-phosphine and DMF, pptn. with CaCl2, soln. and acidifcation. The acid obtd. was sublimed at 90 deg. C and 0.03 mbar to give 4-vinylphthalic anhydride (VPA). A copolymer contg. 10.5 wt% VPA and 89.5 wt% styrene (by FT-IR analysis) was prepd. by radical polymerisation in acetonitrile with AIBN as initiator, followed by re-pptn. from THF/methanol. The prod. had Mn, 5700; Tg, 91 deg. C (cf. 4900, 74 deg. C for 100% styrene homopolymer); a copolymer of 67.4 wt% VPA and 32.6 wt% styrene was soluble in aq. NaOH soln., with Mn = 2200 and Tg = 160 deg. C.