Date of Award

Summer 8-2007

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Polymers and High Performance Materials

Committee Chair

Dr. Robson Storey

Committee Chair Department

Polymers and High Performance Materials

Committee Member 2

Dr. Robert Moore

Committee Member 3

Dr. Douglas Wicks

Committee Member 4

Dr. Charles Hoyle

Committee Member 5

Dr. William L. Jarrett

Abstract

Aromatic-aliphatic poly[L-lactide-/>-(ethyleneoxyethylene terephthalateco- adipate)-6 -L-lactide] triblock copolymers were synthesized and characterized. Hydroxy-telechelic poly(ethyleneoxyethylene terephthalate-co-adipate) (PEOETA) was first prepared via polycondensation and then utilized as an initiator for the ring opening polymerization (ROP) o f L-lactide (LLA) in the presence of stannous octanoate (Sn(Ocfh). Formation o f the block copolymer was confirmed by *H NMR spectroscopy, GPC, DSC and AFM. The polymerization rate induced by the PEOETA macroinitiator was comparable to that o f a small molecule initiator. The mechanical and degradation properties failed to meet project objectives; therefore we focused more attention to the modification of a-hydroxy acid polymers for use in the creation o f degradable polyurethanes.

Linear poly(D,L-lactide) containing a single pendant carboxylic acid group (BHMBA-PDLLA) was synthesized via ring opening polymerization (ROP) o f D,Llactide using 2,2-bis(hydroxymethyl) butyric acid (BHMBA) as an initiator. Characterization of the BHMBA-PDLLA using NMR spectroscopy and gel permeation chromatography confirmed the presence o f the pendent carboxylic acid group and provided evidence o f a linear architecture. Degradation studies were performed on BHMBA-PDLLA polyesters by immersion into aqueous buffered solution (7.4 pH) held at a constant temperature of 37°C. Complete degradation o f the BHMBA-PDLLA occurred at times much earlier than those o f the controls. These poly(oc-hydroxy acid) polymers have shown promising degradation results when chain-extended using L-lysine diisocyanate methyl ester as the chain-extending agent.

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