Effect of different polyethers on surface and thermal properties of poly(urethane-siloxane) copolymers modified with side-chain siloxane

Abstract

Poly(urethane-dimethylsiloxane) (PU-PDMS) copolymers with 4,4 0 -methylenebis(cyclohexyl isocyanate), different polyethers i.e., poly(oxytetramethylene)diol, poly (ethylene glycol), poly(propylene glycol), and a,x-dihydroxy terminated polydimethylsiloxane extended with 1,4-butanediol in two-step solution polymerization were obtained. The PU-PDMS were modified using 1.25 mol% of polydimethylsiloxane which was incorporated into main polyurethane backbone as a side chain. The structure of the synthesized PU-PDMS was confirmed by FTIR as well as 1 H and 13 C-NMR spectroscopy. The effect of different soft segments on free surface energy (FSE) components and thermal stability of poly(urethane-siloxane) copolymers was investigated. The activation energy of the thermal degradation of PU-PDMS using isoconversional methods (OzawaFlynn-Wall and Friedman) was calculated. It was concluded that molecular mass, thermal stability, and FSE of PU-PDMS copolymers depend on polyol used. The apparent activation energy at first step of degradation in nitrogen generally increases with the extent of conversion which may result from complex mechanism related to formation of decomposition products. Hydrophobic character of side-chain siloxane on surface properties of the PU-PDMS coatings was confirmed. The obtained coatings are generally soft with the relative hardness in the range of 0.120-0.027.

Poly(urethane-dimethylsiloxane) copolymers displaying a range of soft segment contents, noncytotoxic chemistry, and nonadherent properties toward endothelial cells

“…The results revealed that surface free energy of the copolymers decreased with increasing PDMS content in the TPUS-HPs, due to the surface activity of hydrophobic PDMS incorporated into the soft segment. The surface energy values of synthesized TPUS-HPs samples (ranging from 25.4 to 35.0 mJ/m 2 ) were slightly higher than values obtained for the siloxane-urethanes presented in the literature (approximately 20 mJ/m 2 ) 46,47 and silicone control sample (18 mJ/ m 2 ), 47 most likely because PDMS covers only part of the TPU surface. The obtained results confirmed the presence of the both hydrophobic siloxane and hydrophilic urethane groups at the surface, giving slight amphiphilic nature to the surface of the synthesized TPUS-HPs.…”

Thermal degradation studies of poly(urethane–siloxane) thermosets based on co-poly(dimethyl)(methyl, 3-glycidoxypropyl)siloxane and epoxy-terminated urethane oligomer

“…PU-Si materials combine advantages of both homopolymers, i.e., good tensile strength and abrasion resistance which are specific for polyurethane, with low free surface energy and glass transition, great elasticity (especially at low temperature) as well as good thermal, chemical and biological stability which are due to polysiloxanes. Owing to their properties, PU-Si are widely used as protection coatings, membranes or medical implants [1][2][3][4][5].…”

“…However, the investigations on polyurethanes with other siloxane structures including polydimethylsiloxane chains terminated only at one side with two hydroxyl groups [5] or polyhedral oligomeric silsesquioxane (POSS) [8] have been recently developed. The thermal degradation studies were also carried out for poly (urethane-siloxane) networks obtained by sol-gel process [9], by cross-linking with hyperbranched polyester [10], or by moisture curing [11].…”

Influence of rigid segment content on the piezoresistive behavior of multiwall carbon nanotube/segmented polyurethane composites

“…The methylene protons adjacent to oxygen in urethanes (a′) are observed at δ = 3.99 ppm which has high intensity for 50 wt % RS content. The doublet at δ = 4.70–4.75 ppm is assigned to protons in the amino group of urethanes (g), although it may also appear at higher values . The methylene protons adjacent to the ether group (a) in the flexible segment are represented as a triplet in δ = 3.35 ppm.…”