Since nanostructured amphiphilic macromolecules capable of affording high ion and water transport are becoming increasingly important in a wide range of contemporary energy and environmental technologies, the swelling kinetics and temperature dependence of water uptake are investigated in a series of midblock‐sulfonated thermoplastic elastomers. Upon self‐assembly, these materials maintain a stable hydrogel network in the presence of a polar liquid. In this study, real‐time water‐sorption kinetics in copolymer films prepared by different casting solvents are elucidated by synchrotron small‐angle X‐ray scattering and gravimetric measurements, which directly correlate nanostructural changes with macroscopic swelling to establish fundamental structure–property behavior. By monitoring the equilibrium swelling capacity of these materials over a range of temperatures, an unexpected transition in the vicinity of 50 °C has been discovered. Depending on copolymer morphology and degree of sulfonation, hydrothermal conditioning of specimens to temperatures above this transition permits retention of superabsorbent swelling at ambient temperature.
Chitosan membrane was modified by the selective oxidization of chitosan molecules on its surface with NO2 gas. FTIR spectra indicated there were plenty of -COOH and -COO groups on the modified membrane surface. The SEM study showed the modified membrane surface was rough rather than smooth as chitosan membrane. All antithrombosis test, hemolysis test and blood cell morphology observation with SEM revealed that modified chitosan membranes have superior blood compatibility to chitosan. 相似文献
Preparation and blood compatibility of different shape polyvinyl alcohol(PVA) membrane were investigated. Firstly, the tabular and tubular[polytetrafluoroethylene(PTFE) capillary as supporter] PVA membranes were prepared; then, methoxy polyethylene glycol(mPEG) was grafted onto the surface of the PVA membranes. The effects of the shape, structure and properties of the membrane surface on blood compatibility were studied in detail. The experiment results show that mPEG modified PVA membranes, especially mPEG modified tubular membrane, could availably repel the adhesion of the platelets. In addition, the anticoagulant mechanism of mPEG with a steric repulsion effectiveness was confirmed further via different grafting methods. 相似文献
The use of persistent electrical polarization in polymers has been explored as a means of reducing surface thrombogenicity. Parallel efforts have been carried out on the characterization of surface properties related to the electret state in polymers, on the stability of the electret state in desirable prosthetic materials under simulated blood pumping conditions, and on in vitro and in vivo blood compatibility experiments. Preliminary correlations among critical surface tension, electrical polarization, and blood compatibility have been obtained. In vitro blood compatibility has been explored using both a modified Lee-White clotting test and a platelet adsorption experiment. No significant difference in clotting time was found for polarized samples; however, those with a negative charge did adsorb fewer platelets. A series of in vivo studies has been carried out using electrified right atrial flags (36) of poly-vinylidene chloride and vena cava rings (22) of FEP Teflon, Hypalon rubber, and Hypalon/2% polysulfonate. Negatively polarized samples showed improved blood compatibility in all cases. About 2/3 of the negatively charged atrial flags showed little or no thrombus and the remainder moderate thrombus whereas 2/3 of the positively charged flags showed severe thrombus. About 3/4 of the negative ring implants showed little or no thrombus. A correlation with anomalous contact angle or low charge was found in 4 of 6 cases of the rings with moderate to heavy thrombus. 相似文献
Abstract To improve the compatibility of styrene-maleic anhydride copolymer/low density polyethylene (SMA/LDPE) blends, LDPE grafted with 2-hydroxyethyl methacrylate-isophorone diisocyanate (LDPE-g-HI) was prepared and blended with SMA of which anhydride was converted to carboxylic acid (SMAAc). The infrared spectra of LDPE-g-HI established the presence of isocyanate group. In the blend morphology, some adhesions between the two phases and much finer dispersions were observed in the SMAAc/LDPE-g-HI blends, indicating that chemical reactions took place during the melt blending. The lower heat capacity change at the glass transition temperature demonstrated that chemical bonds were produced in the SMAAc/LDPE-g-HI blends. From the results of the rheological test, it was found that strong positive deviation from the mixing rule occurred in viscosity for the SMAAc/LDPE-g-HI blends, concerning with good adhesion and finer dispersions. In the measurement of tensile property, the improved mechanical properties for the SMAAc/LDPE-g-HI blends were shown. 相似文献
Journal of Thermal Analysis and Calorimetry - Rivaroxaban is an oral direct Factor Xa inhibitor to treat thrombus. The aim of this study is to investigate the drug–excipient compatibility... 相似文献
Injectable hydrogels have been commonly used as drug‐delivery vehicles and tried in tissue engineering. Injectable self‐healing hydrogels have great advantage over traditional injectable hydrogels because they can be injected as a liquid and then rapidly form bulk gels in situ at the target site under physiological conditions. This study develops an injectable thermosensitive self‐healing hydrogel based on chain‐extended F127 (PEO90‐PPO65‐PEO90) multi‐block copolymer (m‐F127). The rapid sol–gel transition ability under body temperature allows it to be used as injectable hydrogel and the self‐healing property allows it to withstand repeated deformation and quickly recover its mechanical properties and structure through the dynamic covalent bonds. It is hoped that the novel strategy and the fascinating properties of the hydrogel as presented here will provide new opportunities with regard to the design and practical application of injectable self‐healing hydrogels.
