Structure–property relationships of thermoplastic polyurethane elastomers based on polycarbonate diols

Abstract

The phase-separation behavior and morphology of polycarbonate-based polyurethanes were investigated as a function of the soft-segment molecular weight and chemical structure and the 4,4 0 -diphenylmethane diisocyanate/1,4-butanediol based hard-segment contents. Polarized optical microscopy and atomic force microscopy images showed that the surface morphologies changed as the soft-segment molecular weight and hard-segment content varied and also when the sample preparation conditions were modified. An increase in the soft-and hardsegment lengths led to increased phase separation with respect to the lower molecular weight soft segment, and this showed an interlocked and connected morphology of intermixed soft and hard domains. The surface morphology of phase-separated polyurethanes with hard segments composed of more than four to five 4,4 0 -diphenylmethane diisocyanate units contained globular hard-segment domains formed by spherulites, in which the size and connectivity between the branched lamellae changed with the hard-segment size. Interlamellar areas related to the soft segment were seen in the spherulites. Variations in the hard-segment spherulites were observed for polyurethanes based on soft segments of different molecular weights.

Electrospun vascular grafts with improved compliance matching to native vessels

“…Both the as-spun and solvent induced fusions storage moduli were characterized by a lower plateau modulus, broad T g transition, and melting transition (T m ) from 30–40 °C attributed to melting of crystalline soft domains. 43 In contrast, the heat-treated meshes exhibited a higher plateau modulus, sharper T g transition, and reduced (12 hr) or eliminated (24 hr) melting transition. These data indicate a reduction in soft segment crystallinity and an increase in phase separation in the electrospun meshes after heat treatment which was not observed for meshes with solvent-induced fiber fusions.…”

Influence of Poly(ε‐caprolactone) Molecular Weight and Coumarin Amount on Photo‐Responsive Polyurethane Properties

“…Photo‐reversible polymers have attracted much attention in the last few years due to their photo‐responsiveness, which gives the ability to build up reversible crosslinked networks under UV light, that is, under the natural illumination of the low concentration UV component of sunlight or under artificial successive UV light irradiations . They can be processed in several forms, i.e., as films, coatings, hydrogels, or aerogels, and have attracted interest in many industrial sectors for applications including biosensors, adhesives, chemical storage, coatings for the automotive industry, drug delivery, and for self‐healing purposes . Since crosslinked materials are difficult to recycle, photo‐reversible materials also have importance in facilitating recycling or reusability .…”

Structural and Surface Properties of Novel Polyurethane Films

“…PC-PUs with aromatic NCO component are distinguished by excellent toughness, flexibility, durability, chemical-and biostability, and biocompatibility, and thus they are already used or tested in modern medical treatment (cardiovascular implants, heart valves, blood pumps; reconstructive surgery, tissue repair, etc.) [3][4][5][6][7][8]. Compared to PE-PUs, PC-PUs display better in vivo and in vitro chemical stability [8].…”