Effect of Distribution of Substitution on Marine Biodegradability for Paramylon Acetate and Cellulose Acetate

Paramylon acetate and cellulose acetate with different degrees and distributions of substituents were synthesized by two different methods, de-esterification from triesters with NaOH treatment and direct esterification. Paramylon and cellulose acetate obtained by de-esterification exhibited a lower degree of substitution (DS) at C6 and a higher DS at C2 position. All of the acetate samples with different DSs were thermoformable, producing transparent films. However, melt-pressed films obtained through de-esterification exhibited greater flexibility than those prepared via direct esterification. Simultaneously, biochemical oxygen demand (BOD) tests demonstrated that paramylon and cellulose acetate obtained by de-esterification show higher biodegradability than esterification ones with the same DS. This increased biodegradability may be attributed to the lower DS of the acetyl group on C6 for paramylon and cellulose acetate obtained by de-esterification. De-esterification with NaOH treatment was validated as an effective approach for producing polysaccharide esters with excellent mechanical properties and biodegradability for both paramylon and cellulose.