Structural engineering of polyurethane coatings for high performance applications

This paper reviews methods of modifying polydimethylsiloxane (PDMS) polymers to improve their properties for biomedical applications. The modification methods are discussed under three different categories: bulk, surface and other modification techniques. Surface modification techniques include physical and chemical techniques to modify polymer surfaces. Bulk modification techniques include blending, copolymerization, interpenetrating polymer networks (IPNs) and functionalization. The third category includes less common modification techniques.

© 2001 Society of Chemical Industry

Modification of polysiloxane polymers for biomedical applications: a review

Modern cationic vinyl polymerization

The nanophase separated hard segment domains in solvent cast films of a segmented polyurethane and a segmented polyamide elastomer were imaged in real space using phase and topographical information from tapping-mode AFM techniques. A styrene triblock copolymer was used as a control to demonstrate the contrast mechanisms. For the segmented polyurethane and polyamide elastomers, contrast results from local stiffness variations of hard domains beneath a ca. 1 nm thick soft segment overlayer. Domain sizes and dispersity, shape, orientation, spacing, and uniformity in space are uniquely extracted from these real space AFM data. The ca. 7 nm diameter domains were relatively symmetric and uniformly space filling in the polyurethane. They were lamellar or sheetlike in the segmented polyamide elastomer, with a high aspect ratio and no curvature. There was no obvious correlation of lamellae orientation with macrocrystal aggregate (spherulite) position in the polyamide copolymer, while no such aggregates exist in t...

Tapping-Mode AFM Studies Using Phase Detection for Resolution of Nanophases in Segmented Polyurethanes and Other Block Copolymers

Soybean-oil-based waterborne polyurethane dispersions: effects of polyol functionality and hard segment content on properties.

Preparation de polymeres a base de poly(tetramethylene oxyde), methylene bis(phenylisocyanate-4,4' et butanediol (ou bis[hydroxy-4butyl] methylene bis[phenylcarbamate]-4,4'

Properties of polyether-polyurethane block copolymers: effects of hard segment length distribution

: A series of polyurethane block polymers based on hydroxybutyl-terminated poly(dimethylsiloxane) soft segments of molecular weight 2000 were synthesized. The hard segments consisted of 4,4'-methylenediphenylene diisocyanate (MDI) which was chain extended with either 1,4-butanediol (BD) or N-methyldiethanolamine (MDEA). The MDEA-extended materials were ionized using 1,3-propane sultone. The weight fraction of hard segments was in range 0.13-o.39. The morphology and properties of these polyurethane elastomers were studied by variety of techniques. All of these short segment block copolymers showed nearly complete phase separation. The zwitterionomer materials exhibited ionic aggregation with the hard domains. Hard segment crystallinity or ionic aggregation did not affect the morphology. Hard domain cohesion was found to be a more important factor than hard domain volume fraction in determining the tensile and viscoelastic properties of these elastomers. (Author)

Polydimethylsiloxane–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

Properties of polyisobutylene polyurethane block copolymers: 2. Macroglycols produced by the ‘inifer’ technique

A series of polyurethane block copolymers based on hydroxybutyl terminated poly(chloropropylmethyl-dimethylsiloxane) and poly(tetramethylene oxide) soft segments of molecular weights 2100 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) that was chain extended with either 1,4-butanediol (BD) or N-methyldiethanolamine (MDEA). The materials chain extended with MDEA were ionized using 1,3-propane sultone. The weight fraction of the hard segments was in the range 0.30–0.45. The effect of mixed soft segments, chain extenders, and zwitterionization on the extent of phase separation and physical properties was studied by utilizing differential scanning calorimetry and dynamic mechanical, stress-strain, and Fourier Transform Infrared spectroscopy experiments. All of these short segment block copolymers showed nearly complete phase separation. The zwitterionomer materials exhibited ionic aggregation within the hard domains. Although hard segment crystallinity or ionic aggregation did not affect the morphology, hard domain cohesion was important in determining the tensile and viscoelastic properties of these elastomers.

Poly(chloropropylmethyl‐dimethylsiloxane)–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

The properties of a series of polyisobutylene (PIB) based polyurethanes were studied and compared to those reported in the literature for polyether, polyester, and polybutadiene-based polyurethanes. Good phase separation was reflected in the invariance of the soft segment Tn with increasing hard segment content. Increasing hard segment content resulted in larger domains, higher modulus and lower ultimate elongation. The modulus above the soft segment Tn was higher than that previously reported for polyurethanes of similar hard segment contant; improved phase separation and short contour lengths of the PIB chains were cited as possible causes of this behavior. Stress-strain data indicated a change from isolated to interconnected domain morphology with incerasing hard segment contant. Generally similar trends were seen for all types of urethanes. The overall properties of polybutadiene polyurethanes were closest to those of the polyisobutylene polyurethanes studied. The properties of both of these systems were suggested to suffer from significant synthesis problems in urethane formation due to the incompatibility of the nonpolar hydrocarbon soft segment and the polar diol chain extender. Preliminary environmental tests indicated that polyisobutylene based materials exhibit improved hydrolytic stability and reduced moisture permeability compared to polyether and polyester polyurethanes and greater oxidative stability compared to polybutadiene based materials.

P. E. Gibson

Papers

Properties of polyether-polyurethane block copolymers: effects of hard segment length distribution

Polydimethylsiloxane–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

Properties of polyisobutylene polyurethane block copolymers: 2. Macroglycols produced by the ‘inifer’ technique

Poly(chloropropylmethyl‐dimethylsiloxane)–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

Properties of polyisobutylene‐polyurethane block copolymers: I. Macroglycols from ozonolysis of isobutylene‐isoprene copolymer