From thermoplastic elastomers to designed biomaterials

Abstract

This highlight is about my metamorphosis from a cationic polymerization chemist to a biomaterialist (no pun intended) and some of the main events on the road. My earlier career faded away with the discovery of living cationic polymerizations, chronicled in my 1999 highlight, but it also put me on the road to designed biomaterials. My new career started with, and still focuses on, the creation of new polymeric architectures, mainly by cationic techniques, for toughened bone cements, injectable intervertebral discs, nonclogging artificial blood vessels, and amphiphilic networks for controlled drug delivery and immunoisolatory membranes. The enormous complexities of immunoisolation of pancreatic islets are now center stage, and lately we have been using all kinds of techniques to make unique membranes to correct type 1 diabetes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2951–2963, 2005

Nitroxide‐Mediated Polymerization of Methyl Methacrylate Using an SG1‐Based Alkoxyamine: How the Penultimate Effect Could Lead to Uncontrolled and Unliving Polymerization

“…), PMMA is a technical polymer, used in many applications from house furnishing to optic fibers as well as in the building industry. As it is biocompatible, this polymer can also be involved in bone cement formulations, in drug delivery [1,2] and artificial nerves conduits [3] [2-hydroxyethyl methacrylate (HEMA)]. Considerable efforts have been devoted to improve the controlled polymerization of this kind of monomers, in terms of molecular characteristics, overall architecture, nature of end-groups, regio-and stereoselectivities, and particularly block the copolymer design.…”

Medical applications of poly(styrene-block-isobutylene-block-styrene) (“SIBS”)

“…Schematic of polyisobutylene with its alternating secondary and quaternary carbons and lack of labile pendent groups as compared to poly(methylmethacrylate) with its ester side group. The search for PIB-based thermoplastic elastomers, i.e., for elastomers that contains PIB rubbery segments covalently linked to readily thermally-and/or solutionprocessible glassy segments, led the lead author to Kennedy's laboratory at The University of Akron where such polymers were already synthesized [27]. Kennedy's patents protecting the triblock copolymer SIBS were licensed by Corvita Corporation (Miami, FL, Acquired by BSC, Natick, MA) and strengthened by additional patents covering applications in the medical implant arena [28][29][30].…”

“…Living cationic polymerization, a seminal discovery in polymer science, lead not only to SIBS but also to many novel compositions useful for a variety of industrial and medical applications [27].…”

Improved Hydrophilicity from Poly(ethylene glycol) in Amphiphilic Conetworks with Poly(dimethylsiloxane)

“…However, because of its incompatibility with other polymers, phase separation always occurs in their mixtures and thus leads to opaqueness as well as reduced mechanical properties [43]. Covalently crosslinking two types of polymer chains at least can prevent a macroscopic demixing, and this method may result in a phase-separated morphology with domains that remain in the nanoscale range [44][45][46][47][48][49]. Baron introduced PEG into PDMS to form tri-block copolymers, to prepare contact lenses that had the required oxygen permeability and water content balance [37].…”