通过自手性和外消旋酪氨酸衍生的异氰酸酯-酚的自聚加成反应合成了旋光性聚氨酯(LPU和DPU)和外消旋聚氨酯(RPU)。所有聚合物均通过FT-IR表征1此外,还对1 H NMR,GPC,UV-Vis光谱,圆二色性(CD)光谱,TGA和X射线衍射(XRD)以及红外发射率值进行了研究。LPU和DPU是两个对映体,与具有随机盘绕分子链的RPU相比,它们具有螺旋构型和更高的氢键结合度。LPU和DPU的结晶度和热分解温度高于RPU,这是由于二级结构更为规则,有利于形成大量链间氢键。因此,LPU和DPU的红外发射率值较低(8–14μm),分别降至0.611和0.625。
通过自手性和外消旋酪氨酸衍生的异氰酸酯-酚的自聚加成反应合成了旋光性聚氨酯(LPU和DPU)和外消旋聚氨酯(RPU)。所有聚合物均通过FT-IR表征1此外,还对1 H NMR,GPC,UV-Vis光谱,圆二色性(CD)光谱,TGA和X射线衍射(XRD)以及红外发射率值进行了研究。LPU和DPU是两个对映体,与具有随机盘绕分子链的RPU相比,它们具有螺旋构型和更高的氢键结合度。LPU和DPU的结晶度和热分解温度高于RPU,这是由于二级结构更为规则,有利于形成大量链间氢键。因此,LPU和DPU的红外发射率值较低(8–14μm),分别降至0.611和0.625。
Correlation between the secondary structure and hydrogen bonding in optically active polyurethane and its effect on infrared emissivity
作者:Yong Yang、Yuming Zhou、Jianhua Ge、Xiaoming Yang
DOI:10.1016/j.reactfunctpolym.2012.05.006
日期:2012.9
Abstract Optically active polyurethanes (PUs) with different specific rotations were synthesized using a hydrogen transfer addition polymerization procedure with isocyanate–phenols of varying enantiomeric excess. The opticalactivities of the PUs were enhanced with an increase in the enantiomeric excess of the monomers. A helical secondary structure in the PUs with a more compact arrangement of the
Optically active polyurethane@indium tin oxide nanocomposite: Preparation, characterization and study of infrared emissivity
作者:Yong Yang、Yuming Zhou、Jianhua Ge、Xiaoming Yang
DOI:10.1016/j.materresbull.2012.05.045
日期:2012.9
Optically active polyurethane@indium tin oxide and racemic polyurethane@indium tin oxide nanocomposites (LPU@ITO and RPU@ITO) were prepared by grafting the organics onto the surfaces of modified ITO nanoparticles. LPU@ITO and RPU@ITO composites based on the chiral and racemic tyrosine were characterized by FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD), SEM, TEM, and thermo-gravimetric analysis (TGA), and the infrared emissivity values (8-14 mu m) were investigated in addition. The results indicated that the polyurethanes had been successfully grafted onto the surfaces of ITO without destroying the crystalline structure. Both composites possessed the lower infrared emissivity values than the bare ITO nanoparticles, which indicated that the interfacial interaction had great effect on the infrared emissivity. Furthermore, LPU@ITO based on the optically active polyurethane had the virtue of regular secondary structure and more interfacial synergistic actions between organics and inorganics, thus it exhibited lower infrared emissivity value than RPU@ITO based on the racemic polyurethane. (C) 2012 Elsevier Ltd. All rights reserved.