High molecular weight polylactic acid synthesized by applying different binary catalyst

Sanjay Kumar Singh and Prashant Anthony*
Department of Chemistry Sam Higginbottom Institute of Agriculture, Technology & Sciences, Formerly AAI-DU, Deemed-to-be-University, Allahabad-211007, Uttar Pradesh, India.

A B S T R A C T
With the extensive growth of polymers in the modern times and its use almost inevitable, problem of environment pollution has emerged owing to the waste produced from petroleum based non degradable plastics. To overcome this problem researchers all over the world are working to minimize the pollution from polymeric waste, they have concentrated their efforts in mainly two directions viz. to either make the polymer they are using biodegradable to some extent or to use the biopolymer which in turn are biodegradable to replace the petroleum based polymer. One of such polymers which has caught the eyes of researchers is polylactic acid (PLA) it is one of the most useful biopolymers produced by molasses of sugar cane. It has good mechanical properties, physical properties, compatibility with most polymers and biodegradability. Therefore it has managed to find use almost in all the prominent fields of applications like in medicine, packaging and several other areas. It was observed that The properties of PLA changed with the change of molecular weight. The high molecular weight PLA has better properties as compared to low molecular weight PLA. However difficulty is observed in synthesis of high molecular weight PLA, due to high demand and short supply in the market, the researchers are working to  developed new and better ways for synthesis of high molecular weight PLA. This present paper addresses the issue; we have tried to synthesize high molecular weight of PLA by applying various binary catalysts such as tin chloride/maleic anhydride, tin chloride / phthalic anhydride and tin chloride/p-toluene sulfonic acid combinations in direct polycondensation synthesis reaction.  The product obtained was characterized by several methods mainly molecular weight of synthesized polylactic acid was determined by Gel Permeation Chromatography (GPC). According to given data of GPC analysis the molecular weight of PLA was changed with the change of binary catalyst. The results obtained were supported by FTIR spectral analysis. The structure of synthesized PLA was determined by employing FTIR and H^-1 NMR spectral analysis.
Keywords: Synthesis of polylactic acid, Uses of different catalysis, characterization by GPC, FTIR and H¹ NMR