Polyisobutylene‐based polyurethanes with unprecedented properties and how they came about

Abstract

This highlight concerns the birth, development, and present status of unique polyurethanes consisting of polyisobutylene soft segments and conventional hard segments (PIBbased PUs) exhibiting unprecedented combinations of mechanical properties and oxidative/hydrolytic/biological stability. Impetus for developments was to improve the rather poor chemical resistance of conventional polyurethanes by replacing their soft segments with polyisobutylene segments. Research started in the 1980s with the synthesis of a,x-polyisobutylene diols (HO-PIB-OH) by the inifer technique and preparation of PIB-based PUs, which indeed exhibited outstanding stabilities, however, had poor mechanical properties. Because of cumbersome early techniques and expensive reagents, worldwide research and industrial interest waned and developments went into hibernation. Recent discoveries, including living isobutylene polymerization, improved end-functionalizations, inexpensive ingredients, and new insight into PU morphology, lead to simple and less expensive synthesis strategies and, consequently, to resumption of fundamental and applied research. Presently, we can produce kilogram quantities of polyurethanes and polyureas with unprecedented combinations of excellent physical-mechanical-environmental-biological and processing properties. This highlight focuses on facts and insights, which occurred since the discovery and shaped developments. These events are worth reviewing and analyzing because they illustrate how contemporary academic research is driven by curiosity (fun) and economic considerations (money).

Polyisobutylene-based polyurethanes: VII. structure/property investigations for medical applications

“…The preparation of allyl‐ and hydroxyl‐telechelic PIB (A‐PIB‐A and HO‐PIB‐OH), and the two step prepolymer preparation of PIB‐based PUs, has been described . Polymers were purified by washing their hexane solutions sequentially with aqueous NaHCO 3 and water, and precipitating into methanol.…”

Cationic half‐sandwich scandium complex for the synthesis of polyisobutylene with high molecular weight under mild conditions

“…Polyisobutylene and isobutylene–isoprene copolymer (IB‐IP copolymer) attracted a lot of attention in scientific research and industrial application in recent decades, because of their excellent thermal and oxidative stability, chemical resistance, biocompatibility, high hysteresis, and low permeability to gases . To obtain polyisobutylene with high molecular weight ( M n ), the cationic polymerization process of polyisobutylene‐based elastomers is always subjected to energy and environmental issues, such as the use of low temperature (–100 °C) and noxious chlorinated solvents, so the relatively high temperature procedures as well as environmental friendly systems are pursued and have been proposed elsewhere as a desirable option of great scientific interests …”

Hydroxy-telechelic poly(ethylene-co-isobutylene) as a soft segment for thermoplastic polyurethanes

“…PIB was also shown to be biocompatible and approved by the Food and Drug Administration (FDA) for food-related applications. 4 As early as in 1970, Zapp et al prepared PIB-based PUs utilizing sec-hydroxy-telechelic PIB. 2,3 Due to the PIB component, the oxidative, hydrolytic, and thermal stability along with the barrier properties of these PUs are far superior to conventional PUs containing polyesters and polyethers as soft segments.…”