Surface modification of poly (lactic acid) with an improved alkali-acid hydrolysis method

Abstract

In this article, an improved alkali-acid hydrolysis method was used to enhance the hydrophilicity of poly (l-lactic acid) (PLLA). Compared with the traditional alkali hydrolysis method, whether the alkali solution was sodium hydroxide or calcium hydroxide, the new surface modification method using citric acid as the wash solution brought a significant decrease of PLLA film׳s surface water contact angle and a dramatic increase of PLLA׳s surface roughness in a short time, which indicates that this alkali-acid hydrolysis method can effectively improve the hydrophilicity of PLLA. The evident surface modification effect can be mainly attributed to the catalytic ability of the citric acid׳s carboxyl group to cleave polyester׳s ester bond.