A homopolymer or a copolymer comprises a polymerizable compound represented by formula (I):A--X--COCOOR.sub.1 (I)wherein R.sub.1 represents a hydrogen atom, a C.sub.1 -C.sub.5 alkyl group or an aryl group; X represents an oxygen atom, a sulfur atom, --COO-- or --NR.sub.5 -- wherein R.sub.5 is a hydrogen atom or a C.sub.1 -C.sub.5 alkyl group; A represents a C.sub.3 -C.sub.18 alkenyl, alkynyl, alkenylaryl or alkenylaralkyl group, or a group represented by: ##STR1## wherein R.sub.2 and R.sub.3, which may be the same or different, independently represent a hydrogen atom or a C.sub.1 -C.sub.5 alkyl group; Y represents an oxygen atom or --NR.sub.4 -- wherein R.sub.4 represents a hydrogen atom or a C.sub.1 -C.sub.5 alkyl group; n is an integer of 1 to 5; m is an integer of 1 to 10; and 1 is 0 or an integer of 1 to 20;with the proviso that if Y is present, X is not --NR.sub.5 --. Additionally, disclosed are processes of preparing the homopolymer or copolymer as well as the polymerizable compound.