Synthesis and characterization of polyisobutylene-block-polyamides as novel thermoplastic elastomers

Lauren Renee Kucera, University of Southern Mississippi

Abstract

Academic research has focused on two main areas of the living carbocationic polymerization (LCP) of isobutylene (IB): (1) the in-depth study and understanding of mechanistic features of the polymerization, and (2) the utilization and manipulation of the unique aspects of PIB in order to produce practically useful polymeric materials. The research included in this dissertation focuses mainly on the latter objective. This work details three main areas of research: (1) the copolymerization of PIB and polyamides (PA) to form novel thermoplastic elastsomers (TPEs), (2) the mechanical, physical and thermal properties of the novel PIB-PA materials, and (3) the use of click chemistry in the formation of PIB-PA copolymers. In the first study, polyisobutylene (PIB) and polyamide (PA) multiblock copolymers were synthesized via an amidation reaction to make a thermoplastic elastomer. A difunctional carboxylic acid-terminated polyamide was reacted with a primary amine-terminated polyisobutylene (H 2 N-PIB-NH 2 ) in bulk under nitrogen at 215°C to form the segmented copolymers. A series of copolymers were synthesized with varying molecular weights of both the PIB and PA, as well as varying types of PA. 13 C NMR, GPC, and MALDI-TOF-MS were used to confirm the structure of the prepolymers and copolymer, as well as determine the molecular weight. In the second study, the thermal, physical, and mechanical properties of the series of PIB-PA copolymers were examined. DSC, TGA, DMA, density, water contact angle, and mechanical testing were used to fully characterize these novel copolymers. PIB-PA samples were also compared to samples of polyether-block-amide (PEBAX) provided by Arkema as a comparison to industrial grade TPEs. In the final study, azide-alkyne click chemistry was used, as a second method, in the synthesis of segmented multi-block PIB-PA copolymers. The synthesis was performed by reacting a difunctional yne-terminated PA with an azide-terminated PIB in bulk under nitrogen at 200°C with and without a copper(I) catalyst. 13 C NMR, GPC, FTIR, and MALDI-TOF-MS were used to confirm the structure of the prepolymers and copolymer, as well as determine the molecular weight.