CuCl_2对聚乙二醇(PEG)构象和结晶行为的影响

用傅里叶变换红外光谱法(FT-IR)、差示扫描量热法(DSC)、广角X射线衍射法(WAXD)研究了少量过渡金属盐氯化铜(CuCl_2)对聚乙二醇(PEG)构象和结晶行为的影响.Cu~(2+)与PEG分子链中的氧原子有配位键生成,通过溶液电导率的测定,发现一个Cu~(2+)大约与3个PEG链节单元形成配位结构,从而使PEG的构象和结晶行为发生变化,随着体系中CuCl_2含量的增加,PEG分子链中OC-CO旁式构象相对反式构象含量逐渐增加,在CuCl_2含量(w)为7%左右时达到极大值,在CuCl_2含量(w)为9%时,反而是反式构象相对旁式构象含量多些.混合物中PEG的结晶度随着体系中CuCl_2含量的增加逐渐降低,含量(w)为9%时,又有所提高.     

CuCl2硅溶胶和水溶液中铜的电化学行为研究

采用循环伏安法和计时安培法研究了CuCl2硅溶胶和水溶液中铜在玻碳电极上的电沉积和电结晶行为.结果表明在两种CuCl2电解质中,铜的电沉积分两个步骤完成,Cu2+还原为Cu+在硅溶胶中较水溶液中容易;采用吸附-成核模型解析电流-时间暂态曲线,并确定铜的电结晶机理为扩散控制下的连续成核三维生长(3DP),Cu2+在水溶液中的扩散系数较硅溶胶中的大,但相同电位下在硅溶胶中的饱和成核数密度高于水溶液中.     

拉曼光谱法测定冷冻对CuCl2与牛血清白蛋白作用的影响

用CuCl2溶液密度和粘度的变化表征溶液团簇结构的变化,发现CuCl2溶液经冷冻处理后,由于在水的微观结构上形成许多靠氢键结合的小水分子团簇结构,水分子氢键网络的缔合程度变大,溶液密度降低,粘度增大。采用激光显微共聚焦拉曼光谱法对冷冻前后CuCl2溶液与BSA相互作用进行研究,结果表明:Cu2+与BSA作用后,BSA酰胺I带特征峰发生位移,β-折叠构象增加,二硫键构象和酪氨酸外环境发生变化。CuCl2溶液经冷冻-解冻处理后,引起BSA酰胺I带特征峰发生位移的程度和对酪氨酸残基的影响变小,这种相互作用趋弱的效应与水分子团簇结构的变化有关。     

聚乙二醇在超临界二氧化碳介质中的结晶行为

利用DSC和偏光显微镜研究了聚乙二醇在超临界CO2 中的结晶情况 ,超临界条件下得到的晶粒小而均匀 ,DSC测试还表明超临界CO2 可提高聚乙二醇的熔眯和溶解焓。     

聚乙二醇分子量对成纤共聚酯结晶速度的影响

<正> 以聚对苯二甲酸乙二酯(PET)为主体添加聚乙二醇(PEG)的共聚物以及以聚对苯二甲酸乙二酯为主体添加含有磺酸盐基团的共聚组分和聚乙二醇的共聚物是两类重要的成纤共聚醚酯,前者(简称为PEE-1)制成的纤维可用分散染料常压沸染,后者(简称为PEE-2)制成的纤维则可用阳离子染料进行染色。     

AB2星型杂臂共聚物的合成及其结晶行为

通过分子设计, 用过量丁二酸酐将单硬酯酸甘油酯的两个羟基转变为羧基, 再以辛酸亚锡为催化剂, 二苯醚为共沸脱水剂, 使其进一步与不同分子量的端羟基聚乙二醇在负压下共沸脱水偶联, 成功地制备了一系列AB2星型杂臂共聚物, 并采用1H NMR、XRD、DSC、FTIR和偏光显微镜等手段对产物及其结晶行为进行了研究. 1H NMR测试结果表明, 所得聚合物是以二丁二酸甘油酯为核, 一条硬酯酸烷基(GMS)臂和两条聚乙二醇(PEG)臂构成的AB2星型杂臂共聚物[GMS-(SA-PEG)2]. DSC和XRD测试结果表明, 在GMS-(SA-PEG)2中, GMS臂和PEG臂都能结晶; GMS臂的存在不仅影响PEG臂的结晶速度, 同时也影响其结晶的完善程度, 导致结晶温度和结晶熔融温度发生变化; GMS臂相对含量越大, 对PEG结晶行为的影响也越大. 利用偏光显微镜对结晶过程的在线观察结果表明, GMS-(SA-PEG)2的结晶形貌不同于线型聚乙二醇的大球晶, 其先形成细碎的束状晶核, 然后逐步出现生长中的球晶结构, 最后所形成的晶体尺寸有大幅度的减小, 而且其形貌和PEG臂的分子量密切相关. 可见AB2星型杂臂共聚物的结晶是先由GMS臂结晶形成小晶核, 然后再诱导PEG臂球晶的生长. 杂臂的引入对于控制星型多臂共聚物的晶形、晶貌具有重要意义.     

PVA/PEG/Mg(OH)_2复合材料体系的非等温结晶行为

采用熔融共混法,以聚乙二醇(PEG)为增塑剂、Mg(OH)2为稳定剂制备了聚乙烯醇(PVA)/PEG/Mg(OH)2复合材料。利用差示扫描量热仪(DSC)考察了PVA/PEG/Mg(OH)2复合体系中PVA的非等温结晶行为。结果表明:在熔融过程中PEG与PVA大分子形成的分子间氢键,破坏了PVA分子内或分子间的氢键,改善了PVA的热塑性能,使研究其熔融结晶行为成为可能。     

三维穴状化合物[Zn3（pda）2（SO4）（H2O）4·4H2O]的合成与表征

利用H2pda与Zn(II)离子反应得到化合物([Zn3(pda)2(SO4)(H2O)4.4H2O])(pda2-=(4-carboxym-ethyl-piperazin-1-yl)-acetic anion)。通过元素分析、FT-IR和X-ray单晶衍射对化合物进行了结构表征。结果表明:标题化合物内含有一个由配体pda2-阴离子和金属Zn(II)离子形成的三维孔洞结构,孔洞空位填充了一个SO42-阴离子。     

不同水团簇结构Zn（NO3）2稀溶液对BSA构象的影响

研究了Zn(NO3)2稀溶液冷冻-解冻处理前后水团簇结构的变化和对牛血清白蛋白(BSA)构象的影响。Zn(NO3)2稀溶液经冷冻-解冻处理后,由于小的水分子团簇结构的形成,溶液电导率明显增加,密度降低,粘度增加。采用激光显微共聚焦拉曼光谱、傅立叶红外光谱和圆二色光谱研究了与冷冻-解冻处理前后Zn(NO3)2稀溶液作用后BSA构象的变化,结果表明:Zn2+对BSA酰胺Ⅰ带的影响较大,可以降低BSA的α-螺旋结构比例,使BSA的二硫键构象、酪氨酸和色氨酸外环境发生变化。Zn(NO3)2稀溶液经冷冻-解冻处理后,对BSA构象的影响变弱。表现为BSA酰胺Ⅰ带α-螺旋结构含量降低相对较少,对酪氨酸外环境的影响减弱。由此可见冷冻-解冻处理可改变Zn(NO3)2稀溶液水分子的团簇结构,使得溶液的物理化学性质发生变化,进而削弱其对BSA构象的影响。     

聚乙二醇/氮化硼复合材料相变导热性能及其结晶行为

本文采用熔融共混浇筑的方法制备了聚乙二醇/氮化硼(PEG/BN)相变复合材料,并研究了不同尺度片状BN对相变复合材料导热性能和结晶行为的影响。 通过扫描电子显微镜(SEM)、热常数分析仪、红外热成像分析仪和差示扫描量热仪(DSC)研究了相变复合材料的微观形貌、导热系数和相变过程,并利用莫志深法对DSC结果进行了非等温结晶动力学分析。 结果表明,较大片状直径(50 μm)的BN可以更有效地提高聚乙二醇的导热系数,当BN填料质量分数为40%时,相变复合材料的导热系数可达到5.04 W/(m·K)。 在快速降温条件下,片径为50 μm的BN填料可以缩短PEG的半结晶时间,提高结晶速率,使相变复合材料具有较大的相变焓。     

Effect of PEG on the crystallization of PPDO/PEG blends

A new biodegradable polymer system, poly(p-dioxanone) (PPDO)/poly(ethylene glycol) (PEG) blend was prepared by a solvent casting method using chloroform as a co-solvent. The PPDO/PEG blends have different weight ratios of 95/5, 90/10, 80/20 and 70/30. Crystallization of homopolymers and blends were investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). When 5% of PEG was blended, the crystallization exothermal peaks (T_c) of PPDO increased sharply and the crystallization exothermal peaks (T_c) of PEG decreased slightly compared with the homopolymers. The crystallization rates of both components increased, and caused greater relative crystallization degree (X_t%). But when the content of PEG was more than 5%, the crystalline behaviors of blends had no more significant changes accordingly. The melting points of each sample varied little over the entire composition range in this study. The nonisothermal crystallization of PPDO homopolymer and blend (PPDO/PEG = 70/30) were also studied by DSC. The crystallization began at a higher temperature when the cooling rates were slower. The nonisothermal crystallization kinetics of blends was analyzed by Ozawa equation. The results showed that the Ozawa equation failed to describe the whole crystallization of the blend, but Mo equation could depict the nonisothermal crystallization perfectly.     

Synthesis of AB2 star-shaped miktoarm copolymers and their crystallization behavior

A small molecule (GMS-SA₂) with one alkyl chain and two terminal carboxyl groups was synthesized successfully by the reaction of glyceryl monostearate (GMS) with excess succinic anhydride (SA). Then, GMS-SA₂ was used as a coupling agent to condensate with polyethylene glycols (PEG) of different molecular weight or polyethylene glycol monomethyl ether (PEGm) in the presence of stannous octoate as catalyst and diphenyl ether as azeotropic agent. The AB₂ star-shaped miktoarm copolymers were obtained successfully and were characterized by ¹H-NMR, DSC, GPC, XRD, FTIR and polarizing microscopy. The results of DSC and XRD measurements indicate that the crystallization temperature and the melting temperature of the AB₂ star-shaped miktoarm copolymers are different from those of the corresponding linear PEGs, because the existing of GMS-SA₂ alters their crystalline growth velocity and the perfect degree of crystals. It is very important to control the crystal morphology of star-shaped copolymers by introducing the miktoarm into the starshaped polymers and adjusting its content in star-shaped polymers. __________ Translated from Chemical Journal of Chinese Universities, 2007, 28(7): 1365–1370 [译自: 高等学校化学学报]     

PEG接枝氧化石墨烯的制备与细胞成像

通过酯化反应将不同分子量的聚乙二醇(PEG)接枝到氧化石墨烯(GO)表面,得到系列GO-PEG。利用傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)、扫描电子显微镜(SEM)对GO-PEG的结构和形貌进行了表征,用热重分析(TGA)测定了GO-PEG中PEG的接枝量。SEM结果表明GO-PEG的剥离程度高于GO。GO-PEG在磷酸盐缓冲溶液中具有良好的分散稳定性,稳定性与接枝量呈正相关。GO-PEG通过非共价键合作用对荧光素(Flu)的负载量可达1.75 mg·mg-1,且负载量受接枝量影响;另外,GO-PEG对Flu的释放行为具有pH值触发药物释放性能。将接枝PEG的端羟基与Flu共价键合,所得GO-PEG6000-Flu荧光探针实现了对HepG2细胞的成像。     

PEG接枝氧化石墨烯的制备与细胞成像

通过酯化反应将不同分子量的聚乙二醇（PEG）接枝到氧化石墨烯（GO）表面,得到系列GO-PEG。利用傅里叶变换红外光谱（FTIR）、拉曼光谱（Raman）、扫描电子显微镜（SEM）对GO-PEG的结构和形貌进行了表征,用热重分析（TGA）测定了GO-PEG中PEG的接枝量。SEM结果表明GO-PEG的剥离程度高于GO。GO-PEG在磷酸盐缓冲溶液中具有良好的分散稳定性,稳定性与接枝量呈正相关。GO-PEG通过非共价键合作用对荧光素（Flu）的负载量可达1.75mg·mg^-1,且负载量受接枝量影响;另外,GO-PEG对Flu的释放行为具有pH值触发药物释放性能。将接枝PEG的端羟基与Flu共价键合,所得GO-PEG₆₀₀₀-Flu荧光探针实现了对HepG₂细胞的成像。     

异戊橡胶微观序列结构与结晶性能研究

天然橡胶特有的应变诱导结晶能力赋予其优异的力学性能.异戊橡胶作为唯一能够替代天然橡胶的合成橡胶品种,其应变诱导结晶能力受到关注.本文对3种异戊橡胶的微观序列结构进行了分析,并研究了其结晶性能.核磁分析结果表明:3种异戊橡胶的顺-1,4-结构含量差别不大;从1,4-结构单元的键接方式(序列结构)看,SKI-5和YS-IR分子链中顺-1,4-结构单元均以头-尾相接的方式沿分子链排列,不存在头-头键和尾-尾键接方式;SKI-3中约有0.4%~0.5%的1,4-单元采取头-头键接方式,约有0.3%~0.6%的1,4-单元采取尾-尾键接方式;根据定量计算结果,从分子链上1,4-结构单元的序列分布来看,SKI-3的规整性与SKI-5、YS-IR相近或略高.XRD研究结果表明:炭黑填充的天然橡胶硫化胶拉伸至400%以上时发生取向结晶;而炭黑填充的异戊橡胶硫化胶需拉伸至500%以上时才发生取向结晶.基本物理机械性能研究表明:3种异戊橡胶的性能相当,拉伸强度和撕裂强度明显低于天然橡胶;由于结构和组成上的差异,异戊橡胶的结晶能力较天然橡胶差.     

Synthesis and characterization of well‐defined lactic acid–PEG cooligomers and its tricarbonyl rhenium conjugates

This article describes the synthesis and characterization of hydroxyl tailored, molecularly defined biodegradable cooligomers capable of chelating rhenium for potential radiopharmaceuticals. New insights were gained during the synthesis of lactide based on dimethylaminopyridine‐catalyzed transesterification. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Comparison of the Contributions of Tetrahydrofurfuryl Alcohol and PEG to α-Chymotrypsin Renaturation with High Performance Hydrophobic Interaction Chromatography

The contributions of tetrahydrofurfuryl alcohol(THFA) and polyethylene glyco(PEG) to the renature efficiency of α-chymotrypsin were investigated and compared with each other,The maximum increments of bioactivity recovery of α-Chy were found to be 25.1% for THFA,10.4% for PEG,respectively.The experimental results indicated that the denaturant solution containing THFA contributed more to the renaturation of α-Chy in high performance hydrophobic interaction chromatography(HPHIC) than that containing PEG,when the concentration of THFA was 3.2%,the bioactivity recovery of α-Chy is the highest.     

Synergistic effects of PEG and MWCNTs on crystallization behavior of PLLA

This work reported the crystallization behaviors of poly(L ‐lactide) (PLLA) with the presence of polyethylene glycol (PEG) and/or functionalized multiwalled carbon nanotubes (FMWCNTs). The crystallization behaviors occurred in the different conditions, including nonisothermal, isothermal and during the annealing process, were analyzed comparatively using differential scanning calorimetry, wide angle X‐ray diffraction, and polarized optical microscope. The results show that PEG as an efficient plasticizer of PLLA enhances the mobility of PLLA chain segments, which leads to the decrease of glass transition temperature and the enhancement of crystallization ability of PLLA. FMWCNTs as a nucleating agent of PLLA crystallization promote the crystallization of PLLA apparently. With the presence of PEG and FMWCNTs, the crystallization of PLLA is well improved in all conditions, indicating the synergistic effects of PEG and FMWCNTs on PLLA crystallization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 520–528, 2010