NMR研究LLDPE-g-PS对SBS/LLDPE的增容作用

最近,关于用接枝或嵌段共聚物作为增容剂来提高不相容聚合物共混体系相容性的研究越来越受到人们的重视因为这是开发新型高性能聚合物材料最简单最有效的方法之一.通常,适当选择接枝或嵌段共聚物,其链段可能同相应相区的链段相同,或者同某一相相容,因而可起到界面剂的作用:减小不相容组分的界

NMR方法研究无规共聚醚TEO与N100固化反应过程

六次甲基二异氰酸酯(HDI)以其独特的化学性质,在家具、建筑、涂层工业中广泛用作交联剂与粘结剂,在高分子研究领域中常用作新型高分子材料的修饰剂。HDI水合产物N100是端羟基预聚物理想的交联剂,与共聚醚TEO反应生成聚

核磁共振(NMR)研究缩聚与共缩聚高分子的数均分子量 1．全芳香族热致液晶共聚酯

通常用诸如测定溶液粘度的方法测定缩聚与共缩聚高分子的分子量十分不便.对于芳香族缩聚与共缩聚高分子经常遇到选择溶剂的困难.核磁共振波谱(NMR)是研究高分子链结构的最佳物理方法.利用AA-BB缩聚反应中数均聚合度与官能度之间的关系,基于核磁共振的实验

EO／THF无规共聚醚结构研究（Ⅰ）──端羟基液体共聚醚的NMR分析

用核磁共振技术研究了环氧乙烷（ＥＯ）与四氢呋喃（ＴＨＦ）端羟基液体共聚醚（ＴＥＯ）的链结构，定量测定了ＴＥＯ的结构组成参数以及二元组与三元组序列分布。实验结果表明，端羟基液体ＴＥＯ易形成以Ｅ－ＯＨ为端基的线型无规交替结构，且序列分布随ＥＯ／ＴＨＦ组成比而变化。

谷胱甘肽与稀土离子作用的~(13)C NMR研究

本文利用顺磁稀土离子的诱导化学位移变化的性质,研究了多官能团配体谷胱甘肽(GSH)与稀土的配位作用.在水溶液中GSH通过分子两端的羧基负离子与稀土形成遥爪配位结构.谷氨酸端和甘氨酸端羧基与Eu~(3+)的配位稳定常数分别为12.5±0.1L/mol和100.0±0.5L/mol.从~(13)C化学位移的pH变化曲线求得谷氨酸端和甘氨酸端羧基解离的pK_a值分别为2.20±0.02和3.50±0.04.对Dy~(3+)、Ho~(3+)、Er~(3+)、Tm~(3+)和 Yb~(3+)作用下,GSH的~(13)C位移数据分析表明,配体与这些离子形成同构的配合物,分子两端羧基均可能以双齿形式与稀土配位.

EVAc共聚物的序列结构和它的~(13)C NMR谱的关系

本文以EVAc共聚物为例,阐述了EV共聚物序列结构的符号表示与Bovey关系(Ⅰ)的一致性。在此基础上,选择了EV共聚物序列结构的Sung表示并赋予它以化学位移的意义,在二元组和三元组序列水平上分析了EV共聚物的13种序列结构与Sung表示,与取代基参数,与其~(13)C NMR谱13个谱峰之间的一一对应关系。其主要内容由Sung表示与取代基参数之间的α～S_1,β～S_2,γ～S_3,δ～S_4,δ~+～0ppm对应关系表征,从而构架了由EV共聚物的~(13)C NMR谱通向其序列结构的桥梁,建立起研究EV共聚物序列结构的普适方法。

2－乙基己基膦酸单2－乙基己基酯萃取镧系元素的NMR研究

本研究测定了２－乙基己基膦酸单２－乙基己基酯（ＨＥＨ／ＥＨＰ）与镧系元素镧、铈、镨、钕、钐、铕、钬、铒、镱、镥的１Ｈ、（１３）Ｃ、（３１）Ｐ核磁共振谱。对ＨＥＨ／ＥＨＰ的碳骨架进行了详细归属，并根据（３１）ＰＮＭＲ谱峰的积分面积，推测了萃合物可能的配位络合比，（ＨＥＨ／ＥＨＰ与Ｌｎ（Ⅲ）之比）。对铕、镱、镥为６，对铒为５，对钬、钐为４。

氨三乙酸稀土络合物配体交换反应的NMR研究

利用变温13C、1H－NMR研究了过量配体存在下，氨三乙酸稀土络合物Ln（NTA）2（Ln＝Ce，Pr和Nd）配体交换反应，在中性水溶液中，分子间的配体交换过程按如下机制进行：由溶液中自由NTA信号线宽分析了交换速率，确定了反应的活化能．结果表明，分子间配体交换反应的活化能与相应稀土络合物的热力学稳定性有一定关系.

外消旋丙一丝二肽及其稀土配合物的NMR性质

研究了不同ｐＨ值下的Ｄ，Ｌ－丙氨酰－Ｄ，Ｌ－丝氨酸（Ａｌａ－Ｓｅｒ）及其稀土配合物的１Ｈ、１３ＣＮＭＲ谱，对于该种二肽的不同旋光异构体，有可能对其谱线进行区分和指认。测定了酸解常数和稀土配合物的络合稳定常数。通过分离Ａｌａ－Ｓｅｒ的重稀土配合物的接触位移和偶极位移。分析了不同异构体配合物的ＮＭＲ位移的原因。

用NMR方法研究中药山莨菪碱与磷脂脂质体的相互作用

用核磁共振(NMR)方法研究了中药山莨菪碱(anisodamine)与结构不同的3种磷脂脂质体相互作用,二棕榈酰磷脂酰胆碱(DPPC)极性基团空阻较大,山莨菪碱三级胺端不能与P-O键作用,仍处于水相,苯环只能嵌入到甘油骨架C-2附近。二棕榈酰磷脂酸(DPPA)极性头空间位阻较小,山莨菪碱苯环可以直接插入到靠近脂酰链γ-次甲基的位置,而三级胺端与极性头发生静电作用,并且药物可以提高DPPA脂质体的流动性。山莨菪碱通过三级胺端与鞘磷脂(SPM)极性头静电作用较强,而苯环位于SPM脂双层亲水和疏水区界面。药物对3种磷脂双层结构影响很小。

IONIC-CONDUCTIVITY AND DYNAMIC MECHANICAL RELAXATION OF A 2-COMPONENT EPOXY NETWORK-LICLO4 ELECTROLYTE SYSTEM

The correlation between mechanical relaxation and ionic conductivity was investigated in a two-component epoxy network-LiClO4 electrolyte system. The network was composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl ether of glycerol (TGEG). The effects of salt concentration, molecular weight of PEG in DGEPEG and the proportion of DGEPEG (1000) in DGEPEG/TGEG ratio on the ionic conductivity and the mechanical relaxation of the system were studied. It was found that, among the three influential factors, the former reinforces the network chains, reduces the free volume fraction and thus increases the relaxation time of the segmental motion, which in turn lowers the ionic conductivity of the specimen. Conversely, the latter two increase the free volume and thus the chain flexibility, showing an opposite effect. From the iso-free-volume plot of the shift factor log at and reduced ionic conductivity, it is noted that the plot can be used to examine the temperature dependence of segmental mobility and seems to be useful to judge whether the incorporated salt has been dissociated completely. Besides, the ionic conductivity and relaxation time at constant reference temperature are linearly correlated with each other in all the three cases. This result gives an additional experimental confirmation of the coordinated motion model of the ionic hopping with the moving polymer chain segment, which is generally used to explain the ionic conduction in non-glassy amorphous polymer electrolytes.

THE EFFECT OF RADIATION-INDUCED CROSS-LINKING ON THE RELAXATION OF TAUT TIE MOLECULES DURING ANNEALING OF DRAWN LDPE

Shrinkage, retractive stress, and infrared dichroism of the drawn low-density polyethylene (LDPE) as-drawn and irradiated by Co-60-ray have been measured under different annealing conditions. The shrinkage and the disorientation of the irradiated sample was undergone more rapidly than that of unirradiated one as the temperature was continuously increased, surpassing a certain value, and a higher degree of shrinkage and disorientation was achieved finally for the irradiated sample when the samples were annealed with free ends. For the samples heated isothermally with fixed ends, the retractive stress went through a maximum and then attenuated to a limited value, and the degree of such a stress attenuation for the unirradiated sample was much more than that for the irradiated sample. These results show that the taut tie molecules (TTMs) in drawn PE can relax by the pulling of chain segments out of crystal blocks that they anchored in at elevated temperatures higher than the a transition and also by the displacing of microfibrils if the samples were annealed with free ends. The cross-links produced by irradiation prohibit the former process. It was further observed that the dependence of the average extinction coefficient of the band at 2016 cm-1 on that of the band at 1894 cm-1 is related to irradiation and annealing conditions, which has also been explained by the relaxation of TTMs and the function of irradiation-induced cross-linking on the relaxation.

水溶液中稀土离子与甘氨酸、丝氨酸、天冬氨酸作用的~(13)C NMR研究

测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的~(13)C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm～0.25nm,天冬氨酸的y-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的~(13)C诱导位移的系统分析表明,配体~(13)C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C_0)│<│A(C_α)│;A(C_0)为正,A(C_α)为负;(2)│G(C_0)│>│G(C_α)│;配体碳核的G均为负值。