A process of forming a side-chain-functionalized polyhydroxyalkanoate (PHA) material is disclosed. The process includes forming a PHA material having a hydroxyl-terminated side-chain. The process also includes utilizing the PHA material having the hydroxyl-terminated side-chain to form a side-chain-functionalized PHA material having a side-chain with a terminal cross-linkable functional group, for example, sulfhydryl group, in order to form reversibly cross-linked PHA material.