Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
DeChristian Guthrie - Savannah State University
Co-Author(s): Pascal Binda, Savannah State University, Savannah, GA
Polyesters are commonly useful in industries such as packaging and bio-medical for drug delivery devices because of their extensive properties including biodegradability. Based on similar methods used by Hong and Chen of Colorado State University for the copolymerization of MBL and ɛ-CL using La[N(SiMe3)2]3 as catalyst, the lanthanide catalysts will successfully polymerize MBL to produce ring-opening polyester PMBL at low temperatures. Ring opening polymerization of cyclic esters have been successful using heteroleptic lanthanide complexes (LLnX). New lanthanide complexes [LDLaN{Si(CH3)2] (1), and LDLaOMe (2) were synthesized from an acid-base ligand exchange reaction with ligand H2LD and corresponding homoleptic lanthanide compound La[N{(Si(CH3)3}2)]3 at -50°C in toluene for 4 hours. Complexes (1) and (2) were tested as catalysts for the ring opening homopolymerization of MBL (α-methylene-γ-butyrolactone). Polymerizations were tested at temperatures in the range of -45 to 130°C and characterized by 1H NMR. Based on findings from 1H NMR, the polymerizations were achieved at different temperatures. The conversion of MBL was greater with 0.5 mol % catalyst at -45°C compared to polymers obtained with 0.2 mol % catalyst. Complex (2) was also more reactive than (1) and produced more polymer as a result. Future research involves DSC and GPC analyses of polymers, free-radical cross-linking using 2,2’-Azobisisobutyronitrile (AIBN) and low dose gamma radiation.
Funder Acknowledgement(s): Department of Defense
Faculty Advisor: Pascal Binda, bindap@savannahstate.edu
Role: All syntheses including ligand, heteroleptic catalyst, and polymerizations were done by me.