One way to synthesize a biodegradable polymer using renewable resources as starting materials is by producing polylactic acid PLA from lactic acid, which can be derived from renewable resources like corn starch or sugarcane. The synthesis of PLA involves two main steps: 1 fermentation of renewable resources to produce lactic acid, and 2 polymerization of lactic acid to form PLA.1. Fermentation of renewable resources:Lactic acid can be produced through the fermentation of renewable resources like corn starch or sugarcane. The process involves the conversion of these resources into glucose, which is then fermented by microorganisms e.g., Lactobacillus to produce lactic acid. The fermentation conditions should be optimized to achieve high lactic acid yield, which typically involves maintaining a pH of around 5-6, a temperature of 30-40C, and an appropriate nutrient supply for the microorganisms.2. Polymerization of lactic acid:The polymerization of lactic acid to form PLA can be carried out through two main routes: a polycondensation, and b ring-opening polymerization ROP of lactide, which is the cyclic dimer of lactic acid.a Polycondensation:In this process, lactic acid molecules are reacted together to form PLA with the elimination of water. The reaction is typically carried out at high temperatures 150-200C and under vacuum to remove the water formed during the reaction. The use of a catalyst, such as tin II oxide SnO or tin II alkoxides e.g., tin II 2-ethylhexanoate , can help to increase the reaction rate and achieve higher molecular weight PLA.b Ring-opening polymerization ROP of lactide:This method involves the conversion of lactic acid to lactide, followed by the ROP of lactide to form PLA. The conversion of lactic acid to lactide can be achieved by heating lactic acid at high temperatures 180-230C under vacuum. The ROP of lactide is typically carried out using a catalyst, such as tin II alkoxides e.g., tin II octoate or organometallic complexes e.g., aluminum isopropoxide . The polymerization conditions, such as temperature, reaction time, and catalyst concentration, should be optimized to achieve the desired molecular weight and properties of PLA.To achieve specific properties of the biodegradable polymer, factors such as molecular weight, degree of crystallinity, and stereochemistry can be controlled during the synthesis process. For example, the use of different catalysts or varying the reaction conditions can result in PLA with different stereochemistry e.g., isotactic, syndiotactic, or atactic , which can influence the polymer's properties like thermal stability, mechanical strength, and biodegradation rate. Additionally, blending PLA with other biodegradable polymers or incorporating additives can help to tailor the properties of the final product for specific applications.