This paper describes the synthesis of a series of ABA-type triblock copolymers of trimethylene carbonate and -caprolactone with various molar ratios and analyses the thermal and mechanical properties of the resulting copolymers. The structures of the triblock copolymers were characterized by 1 H and 13 C nuclear magnetic resonance spectroscopy, FT-IR spectroscopy and gel permeation chromatography. Results obtained from the various characterization methods proves the successful synthesis of block copolymers of trimethylene carbonate and -caprolactone. The thermal properties of the block copolymers were investigated by differential scanning calorimetry. The T m and H m values of the copolymers decrease with increasing content of trimethylene carbonate units.Two T g s were found in the copolymers. Furthermore, both of the T g values increased with increasing content of trimethylene carbonate units. The mechanical properties of the resulting copolymers were studied by using a tensile tester. The results indicated that the mechanical properties of the block copolymers are related to the molar ratio of trimethylene carbonate and -caprolactone in the copolymers, as well as the molecular weights of the resulting copolymers. The block copolymer with a molar composition of 50/50 possessed the highest tensile stress at maximum and modulus of elasticity. Block copolymers possessing different properties could be obtained by adjusting the copolymer compositions.
The ultrafine fibers of poly(ε-caprolactone) (PCL) composited with different Polyvinyl Pyrrolidone (PVP) content were successfully prepared by electrospinning method. The morphology, hydrophilicity and in vitro degradation behavior of samples were characterized by Scanning Electron Microscopy (SEM), water contact angle and weight loss rate. Pore size and distribution on the fibers changed with the increase of PVP content. The hydrophilicity of PCL membrane was improved by addition of PVP. When the content of PVP was 25% and 50%, the water contact angle approached zero. The degradation was essentially a dissolution process of PVP on the first 7days. Since large specific surface, high porosity and different crystallinity, percent degradation loss of electrospun fiber membranes were about 1 to 12 times higher than that of cast films.
Electrospun poly(ε-caprolactone) (PCL) fibers containing silver nanoparticles were successfully prepared from PCL solutions added silver collide. The silver collide were obtained by N, N-dimethylformamide (DMF) reducing silver nitrate (AgNO3). The effects of PCL concentration and the content of silver nanoparticles on composite fibers morphology were characterized by field-emission scanning electron microscopy (FESEM). The existence of Ag nanoparticles on the electrospun fibers was approved by X-Ray diffraction (XRD). Simultaneously, the contact angles of fiber membranes were measured. The results indicated that uniform fibers were obtained when PCL concentration was 9wt%, the average diameter of fiber was significantly decreased as increasing the amount of silver collide, and Ag nanoparticles were successfully incorporated into the PCL fibers.
Database of color matching system for supercritical CO2 dyeing was established and its accuracy was verified. The K/S value curves of each of the trichromatic disperse dyes (C.I. Disperse Orange 30, C.I. Disperse Red 167 and C.I. Disperse Blue 79) were parallel, which indicated that the samples suits for building database of color matching system. The color matching system was emended with calibration coefficients that were derived from data of several samples dyed with a mixtures of disperse dyes in supercritical CO2. The recipes for a given sample could be found with the calibrated color matching system in supercritical CO2 dyeing.
The composite nanofiber membranes of poly (ε-caprolactone)/poly(vinyl pyrrolidone) (PCL/PVP) containing silver nanoparticles were prepared by electrospinning method. The morphology of composite nanofibers was characterized by scanning electron microscopy (SEM). The silver nanoparticles on the electrospun fibers were characterized by X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The contact angle and water uptake of PCL/PVP/Ag nanofiber membranes were measured. The SEM photos indicated that the average diameter of the fibers was significantly decreased with the addition of silver nanoparticles. The X-Ray images showed that Ag nanoparticles were distributed on the surface of nanofiber membranes. When the PVP mole ratio was higher than 15%, the nanofiber membranes showed good hydrophilic property. The PCL/PVP/Ag nanofiber membranes could be applied to prepare wound dressing.
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