Macromolecular Engineering via Carbocationic Polymerization: Branched Structures, Block Copolymers and Nanostructures

Abstract

This article features macromolecular engineering via carbocationic polymerization, the focus of research of the recently established Macromolecular Engineering Research Centre (MERC) at the University of Western Ontario. The fundamental philosophy of MERC is interdisciplinary research with a strong industrial orientation, while emphasizing the quest for fundamental understanding of polymerization processes and polymer structure‐property relationships. First, a brief overview of living polymerizations in general, and living carbocationic polymerizations in particular will be given. This latter technique is of interest because some monomers (e. g., isobutylene) can be polymerized by cationic techniques only, to yield polymers with unique properties (e. g., polyisobutylene with superior chemical and oxidative stability, low permeability and high damping). This will be followed by an overview of our research strategy and a summary of our latest results. These include the development of a fiber‐optic mid‐FTIR method for the real‐time monitoring of low temperature polymerization processes, the discovery that selected epoxides initiate effectively the living carbocationic polymerization of isobutylene, fundamental studies into the mechanism and kinetics of living carbocationic polymerization, and the design and synthesis of various polymer architectures (e. g., branched homo‐ and block copolymers) with improved properties and nanostructured phase morphologies.

Online Monitoring of Polymerizations: Current Status

“…[13] Puskas et al used Fourier transform mid-infrared (FT-MIR) spectrometers for the continuous monitoring of the carbocationic living polymerization of isobutylene and styrene in solution. [14][15][16] Monitoring of metathesis polymerization reactions by in situ FT-MIR spectroscopy was utilized by Weiss and coworkers. [17] In situ attenuated total refection Fourier transform infrared (ATR-FTIR) spectroscopy was also employed to study the kinetics of carbocation-and ring-opening-polymerization processes as well as metallocene-catalyzed copolymerizations, polycondensations, and post-polymerization modifications ( Figure 1).…”

Combinatorial Methods, Automated Synthesis and High‐Throughput Screening in Polymer Research: Past and Present

“…Fluorescent imaging was shown to be applicable to pH sensing in a 96-well microtiter plate format, [109] and an optical biosensor was developed for the fast analysis of streptomycin residues in pasteurized milk. [110] Fiber optic mid-IR [111] or FT-IR [112] probes were developed for the online monitoring of polymerization reactions. Fourier-transform infrared spectroscopy (FT-IR) was used to monitor living isobutylene and ethylene oxide polymerizations, [113] as well as the copolymerization of ethene and 1-hexene.…”

Polyisobutylene‐based biomaterials

“…We continued investigating structure-property relationships in PIB-PS block copolymers, and developed new carbocationic initiators, and new PIB-based structures. [51][52][53][54][55][56][57][58][59][60][61][62][63][64] We consider linear triblock PS-PIB-PS (Fig. 1) the first generation of this new class of TPEs, with multiarm-star PIB-PS being the second generation and arborescent PIB-PS the third generation.…”