SYNTHESIS OF POSITIVELY CHARGED POLY(LACTIC ACID) FOR PREPARATION OF ELECTROSPUN FIBER

Abstract

Poly(L-lactic acid) (PLLA), a biodegradable and biocompatible polyester, has been widely investigated as a very promising replacement for packaging and biomaterials in many applications. The high hydrophobic character of PLLA posed a challenge in developing a biodegradable polymer having ‘positive’ charges in its structure. In this work, electrospun fiber mats fabricated from commercial-grade PLLA doped with low molecular weight PLLA having two positively charged end groups (PLLAdi+) were prepared with the aim to develop a nano-fiber mat that possessed positive charges in the fibers. PLLAdi+ with molecular weight ranged from 4 to 15 kDa were synthesized by incorporating glycidyl trimethylammonium chloride (GTMAC) into the PLLA chain ends. Up to 55% reduction (from 462 to 208 nm) of fiber diameter was achieved when increasing the PLLAdi+ (4 kDa) content mixed in the commercial PLLA fiber from 10 to 40 wt%. In addition, the fiber diameter also decreased from 650 to 462 nm (28% reduction) when decreasing the molecular weight of PLLAdi+ used from 15 to 4 kDa, as determined by SEM. Besides the size reduction of the fiber when added PLLAdi+, the hydrophilicity of PLLA fiber mat as determined by air-water contact angle was decreased significantly from 137º to 123º (p < 0.05) when 10 wt% PLLAdi+ was added compared to the non-doped mat. The contact angle was also decreased when the PLLAdi+ content increased. The thin and hydrophilic PLLA fibers were successfully prepared and could potentially be used in applications related to aqueous environment.