A copolymer represented by the general formula: ##STR1## [wherein, A denotes an alkylene group of 2 to 4 carbon atoms, the --A--O--.sub.a chain may have at least one oxy-alkylene unit bonded in any possible order, a denotes an integer of the value of 1 to 100, R.sup.1 and R.sup.2 independently denote...http://www.google.com/patents/US4471100?utm_source=gb-gplus-sharePatent US4471100 - Copolymer and method for manufacture thereof
