Synthesis,Characterization And Application Of Starch Grafted Copolymer

Biodegradable polymer materials have been attracting more and more research interestsin the last decade. Starch is a potentially useful material for biodegradable plastics because ofits natural abundance and low cost. However, the starch-based materials, such asthermoplastic starch, have some drawbacks, including poor long-term stability caused by thewater absorption, poor mechanical properties, and process ability. Starch graft copolymer idrepresentative of the modification of the starch molecule by chemical derivation. Starch graftcopolymers such as starch–g-polystryrene (PS), have been synthesized by generation freeradicals on starch and reacting these free radicals with the respective vinyl monomers.However, these copolymers with vinyl polymer branches also have limited biodegradabilitybecause of the presence of their non-degradable branch units, although their properties areacceptable for applications. Another effort in chemical modification of starch is graftingstarch with biodegradable polymers.The graft-copolymers such as starch-g-PCL andstarch-g-PLA can be completely biodegraded by bacteria or under natural conditions and haveimproved mechanical performance.The dissertation was focused on the preparation of starch-g-polycaprolatone(st-g-PCL)and starch-g-poly(L-lactide) (st-g-PLA). The structure of st-g-PCL and st-g-PLA wascharacterized with IR, DSC, SEM and WAXD.Several results and conclusions had been achieved:1. Starch-g-polycaprolatone (PCL), was synthesized by using the ring-opening graftpolymerization of a ε-caprolactone (CL) monomer onto starch in the presence of Sn (Oct) 2.The structure of the starch-g –PCL was characterized with IR, DSC, SEM and WAXD.2. A novel biodegradable starch grafted copolymer, starch-g-poly(L-lactide)(st-g-PLA),was synthesized in situ by the ring-opening graft polymerization of a L-lactide(LA) monomer onto the surface of the SM-St granules in the presence of Sn(Oct)2 asacatalyst.3. The property of starch grafted copolymer as controlled release film wasresearched,and this conclusion was achieved : in water,urea dissolved in five seconds,butwhen it was packed with starch grafted copolymer,the release time could reach 24 hours ormore. Among the compare of the three samples, we could see that: the long of the graftedpoly(L-lactide),the better controlled release effect of the starch-g-poly(L-lactide), and thecontrolled release effect of starch-g-polycaprolatone is better than starch-g-poly(L-lactide).