What are the monomers used for preparation of PHBV?

PHBV stands for Poly $\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate.

It is a biodegradable copolymer obtained by the copolymerisation of 3-hydroxybutanoic acid (\beta$-hydroxybutyric acid) and 3-hydroxypentanoic acid (\beta$-hydroxyvaleric acid).

Answer: $\beta$-Hydroxy butyric acid and $\beta$-Hydroxy valeric acid