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Polyurethane copolymers based on α,ω-dihydroxypropyl poly(dimethylsiloxane) (PDMS) with a range of soft segment contents were prepared by two-stage polymerization, and their microstructures, thermal, thermomechanical, and surface properties, as well as in vitro hemo- and cytocompatibility were evaluated. All utilized characterization methods confirmed the existence of moderately microphase separated structures with the appearance of some microphase mixing between segments as the PDMS (i.e., soft segment) content increased. Copolymers showed higher crystallinity, storage moduli, surface roughness, and surface free energy, but less hydrophobicity with decreasing PDMS content. Biocompatibility of copolymers was evaluated using an endothelial EA.hy926 cell line by direct contact, an extraction method and after pretreatment of copolymers with multicomponent protein mixture, as well as by a competitive protein adsorption assay. Copolymers showed no toxic effect to endothelial cells and all copolymers, except that with the lowest PDMS content, exhibited resistance to endothelial cell adhesion, suggesting their unsuitability for long-term biomedical devices which particularly require re-endothelialization. All copolymers exhibited excellent resistance to fibrinogen adsorption and adsorbed more albumin than fibrinogen in the competitive adsorption assay, suggesting their good hemocompatibility. The noncytotoxic chemistry of these synthesized materials, combined with their nonadherent properties which are inhospitable to cell attachment and growth, underlie the need for further investigations to clarify their potential for use in short-term biomedical devices.

Novel macroporous functionalized copolymers with different cross-linker concentrations and porosity parameters were synthesized by reaction of the pendant epoxy groups of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EGDMA)) with hexamethylene diamine, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and α,ω-diaminopropyl poly(dimethylsiloxane). The copolymers were prepared in forms of spherical beads and characterized by Fourier transform infrared (FTIR), 13 C and 29 Si solid-state NMR, mercury porosimetry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Copolymers prepared with the higher cross-linker concentrations have better thermal stability, higher glass transition temperatures, higher specific surface areas, and smaller pore diameters that correspond to half of the pore volumes. Our results show that functionalization significantly changed porosity parameters, mechanism of thermal degradation, and increased thermal stability in comparison with the initial copolymers. These macroporous copolymers could potentially have many applications, i.e. for sorption of heavy and precious metals or as material for gas chromatography columns.

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Novel poly(dimethylsiloxane)-based polyurethane nanocomposites (TPU-NCs) were synthesized using in situ polymerization with the nanoclay, Cloisite 30B. DSC, TGA and DMTA analyses showed that TPU-NCs with organoclay content ≤5 wt % exhibited increased thermal stability, storage modulus and hard segment melt temperatures, but decreased degrees of crystallinity. TPU-NCs displayed increased surface hydrophilicity and enhanced surface free energy with increasing organoclay content. SWAXS confirmed intercalated formations of organoclays in the nanocomposites. Individual clay particles on surfaces of TPUs with lower organoclay loadings (1 or 3wt %), or organoclay agglomerates in TPUs with higher amounts of organoclay (≥ 5 wt %) were detectable using SEM. The relatively smooth and homogeneous character of pure TPU and the distinctly heterogeneous and rough surfaces of TPU-NCs were detected via AFM. Among the nanomaterials prepared, TPU-NC with 1 wt % of organoclay provided the best balance between organoclay concentration and the functional properties desired in biomedical applications.