Polylactide (PLA ) is a biobased–biodegradable polymer which is derived from lactic acid and has numerous potential applications, some of which are limited by its moisture barrier and thermal properties. Prior studies have been inconsistent about how moisture sorption in PLA varies with crystallintity and molecular weight.

This research is a systematic study of how moisture sorption in PLA depends on molecular weight and aliphatic content via end group modification. PLA with varying aliphatic content was achieved by initiating ring opening polymerization of L-lactide with different long chain aliphatic fatty alcohols. Molecular weight was controlled by varying the ratio of L-lactide monomer to alcohol (C16 Palmityl, C10 Decyl, C4 Butyl) initiator and triethylaluminum ethoxide was used as a catalyst because of the better control over molecular weight.

PLA with different molecular weight and with varying end groups have been synthesized and characterized by GPC, DSC, and NMR. Moisture sorption in PLA was measured with Quartz Crystal Microbalance (QCM). Initial experiments of QCM have shown that by increasing the aliphatic content of the end group there was a significant decrease of up to 15% in the moisture sorption of water in PLA.