If in Formula I R3, R4, and one of either R2, or R1, are hydrogen atoms and the other of R2, and R1 is a methyl radical and n is 1 then the polymer would be a homopolymer of ??-hydroxy butyrate, sometimes referred to as PHB. If in Formula I R3 and R4 are hydrogen and one of R1 and R2 is hydrogen and the other is an ethyl radical and n is 1 then the polymer would be a homopolymer of ??-hydroxy vale