Improving the molecular weight and synthesis of a renewable biomimetic adhesive polymer

Renewable materials are in demand to replace the petroleum-based glues we use on a daily basis. Such substitutions will not take place until bio-based adhesives can meet or exceed the performance of current materials. Work presented here examines several chemical parameters in order to improve the molecular weight and synthetic strategy for a polymer that combines polylactic acid with mussel mimicking catechol, ("catechol-PLA"). Altering the polymerization time as well as the deprotection time and temperature afforded better control over both molecular weights and yields. Dispersity and molecular weight were shown to both be parameters tunable to improve adhesion strength. Cross-linking with iron improved the adhesion of low molecular weight polymers, bringing performance up to that of the longer chain counterparts. Such cross-linking and molecular weight effects were seen to alter the balance of adhesive and cohesive interactions. Such development and understanding of renewable polymer systems may help to hasten future competition with petroleum-based adhesives.