Coordination insertion of L-lactic acid

Abstract

Poly(L-lactide) (PLLA) is a well-known biodegradable polymer, which has a wide range application in the biomedical, textile, and packaging fields. PLLA is one of the polymers, which can be derived from agricultural resources such as corn, cassava, and potato by mean of fermentation to produce L-lactic acid as monomer. In this work, we attempted to synthesize high molecular weight PLLA via ring-opening polymerization and chain extension. We studied L-lactide synthesis from L-lactic acid. PLLA has been synthesized by L-lactide ring opening. The effects of two initiator (stannous (II) 2-ethylhexanoate and creatine hydrate) were investigated. Suitable conditions for polymerization using stannous (II) 2-ethylhexanoate and creatine hydrate was120 degrees celsius at the reaction time 24 hours and 48 hours respectively. [superscript1]H NMR and [superscript13]C NMR were used for PLLA characterization. GPC and DSC were used to determine the molecular weight and T[subscripeg] of PLLA. The results showed that by ring-opening polymerization of L-lactide using stannous (II) 2-ethylhexanoate and creatine hydrate as the initiators, PLLA with wide range molecular weight of 10,000-30,000 was obtained. In addition, chain extender was used in this study in order to further increase the molecular weight of PLLA. Tolylene 2,4 diisocyanate terminated poly 1,4-butanediol prepolymer could be more effectively used to increase molecular weight of PLLA than 1,6-hexamethylene diisocyanate, Suitable ratio ratio of PLLA to tolylene 2,4-diisocyanate terminated poly 1,4-butanediol prepolymer was 1:1.1 and gave T[subscriptg] at 45.1 degrees celsius.