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101.
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STUDY ON SEGMENTED POLYURETHANE WITH MIXED SOFT SEGMENTS OF POLYCHLOROMETHYL METHYL SILOXANE AND POLYTETRAMETHYLENE OXIDE 总被引:2,自引:0,他引:2
Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and poly-tetramethylene oxide in different weight fractions were synthesized. The phase separation ofsamples was studied using DSC and dynamic mechanical property analysis. The results showedthat the introduction of chloromethyl group into polysiloxane increased its polarity and henceimproved the miscibilities with polytetramethylene oxide and polyurethane hard segment.Particularly, in the case of N-methyldiethanolamine extended materials, the surface and tensileproperties of these samples can be adjusted by various ratios of two soft segments. 相似文献
103.
Simultaneous and sequential poly(N-isopropyl acrylamide) (PNIPAAm)/poly(dimethyl siloxane) (PDMS) semi-interpenetrating polymer networks (IPNs) with different linear PDMS contents were prepared by free radical polymerization method. Their phase morphologies have been characterized by FTIR, DSC and SEM. The simultaneous semi-IPNs exhibited phase transition temperatures (Tpt) shifted higher temperature from glass transition temperatures (Tg) of their respective homopolymers, suggesting a heterophase morphology and only physical entanglement between the PNIPAAm network and linear PDMS with high molecular weight (Mn≈9000 g/mol). For sequential semi-IPNs, the shift of Tpts towards lower temperature suggested that the chemical interaction between the constituents of the IPNs increased with increasing PDMS content in the network. In addition, these semi-IPNs were characterized for their thermo-sensitive behaviour by equilibrium swelling studies. The results showed that incorporation of hydrophobic PDMS polymer into the thermo- and pH-sensitive PNIPAAm and P(NIPAAm-co-IA) (itaconic acid) hydrogels by semi-IPN formation decreased swelling degrees of IPNs without affecting their LCSTs whereas addition of acrylated PDMS (Tegomer V-Si 2250) as crosslinker instead of N,N′-methylenebisacrylamide (BIS) into the structures of these hydrogels changed their LCSTs along with their swelling degrees. 相似文献
104.
The spreading behaviour of binary and ternary equimolar mixtures of siloxane surfactants of general formula [(CH3)3SiO]2CH3Si(CH2)3 (OCH2CH2) nOCH3, n = 3–9, has been investigated. The mixtures show a pronounced temperature dependence on the initial spreading rate. Mixtures imitating the average oligoethylene glycol chain length n = 5 are the fastest spreaders at 15 °C. At 23 °C and 40 °C these mixtures spread fastest sucking n = 6 and n = 8, respectively. For a given average chain length an increasing length difference between the components of the binary mixtures reduces the initial spreading rate. Nevertheless, substantial differences between the phase transition temperature Tc from the lamellar phase (Lα) into the two‐phase state (2Φ) and the actual spreading temperature are tolerated. A clear relation between phase transition temperature Tc and initial spreading rate does not exist. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
105.
R. Wagner L. Richter Y. Wu J. Weißmüller J. Reiners E. Hengge A. Kleewein K. Hassler 《应用有机金属化学》1997,11(8):645-657
The surface tensions, wetting tensions, contact angles and solid/liquid interfacial tensions of defined siloxanes as well as those of analogous carbosilanes, polysilanes and neopentyl substituted silanes were determined. The wetting experiments were carried out on a glass plate coated with perfluoroalkyl methacrylate (FC 722®). The siloxanes possess the lowest surface tensions. Due to the presence of oxygen atoms in the siloxane backbone, a donor–acceptor portion (γ+/−lv) of the surface tension of about 1–2 mN/m was determined. The solid/liquid interfacial tension also contains a donor–acceptor portion (γ+/−sl). Its value is almost identical to that of γ+/−lv. The γ+/−sl differences between individual molecules of the same surface tension are responsible for contact angle differences of up to 4°. © 1997 John Wiley & Sons, Ltd. 相似文献
106.
L. Bourget P. Hubert Mutin A. Vioux J. M. Frances 《Journal of polymer science. Part A, Polymer chemistry》1998,36(13):2415-2425
Low-viscosity, methoxylated polysiloxane resins incorporating Me2SiO2/2 (D) and SiO4/2 (Q) units were prepared using nonhydrolytic condensation between Si—Cl and Si—OMe groups with the formation of MeCl, catalyzed by a Lewis acid. With the commonly used catalysts, condensation between two Si—OMe groups, with formation of Me2O, also took place to a large extent, hindering the control of the degree of condensation of the resins. Several catalysts were tested by monitoring the formation of MeCl and Me2O using sealed NMR tubes and 1H-NMR spectroscopy. The best compromise between reactivity and selectivity was obtained with ZrCl4. Resins with various compositions were prepared in the absence of solvent by condensation between Me2SiCl2 and Si(OMe)4 at 130°C, catalyzed by 1 mol % ZrCl4. They were characterized using viscosimetry, gas chromatography coupled with mass-spectrometry (GC-MS), and quantitative 29Si-NMR spectroscopy. The resins consisted of a complicated mixture of oligomers, linear or branched (n > 1) and cyclic (n > 3), with a high degree of D/Q bonding. The distribution of Si—OMe and Si—OSi bonds and the bonding between D and Q units were found to be nearly random. This was ascribed to the occurrence of Si—OSi/Si—OMe and Si—OSi/Si—OSi redistribution reactions that reached equilibrium during the synthesis. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2415–2425, 1998 相似文献
107.
Won Ho Jo Ho Sang Lee Sang Cheol Lee 《Journal of Polymer Science.Polymer Physics》1998,36(15):2683-2689
Interfacial tension between immiscible polymer pairs was predicted by using a square gradient theory in conjunction with the Flory–Orwoll–Vrij equation-of-state expression for the free energy of mixing. The contact interaction parameter was determined by fitting the equation-of-state theory to experimental cloud points taken from the literature, and the square gradient coefficient was estimated from the relation derived from a scattering function. The modified square gradient theory could successfully predict both the magnitude and temperature dependence of interfacial tension between polystyrene and poly(methyl methacrylate), although no adjustable parameters were used in calculating interfacial tension. The molecular weight dependence of interfacial tension was also successfully predicted. The contribution of free volume on interfacial tension is analyzed for two systems: polystyrene/poly(methyl methacrylate) and polystyrene/poly(dimethyl siloxane) blends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2683–2689, 1998 相似文献
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