基于星型聚4-甲基-ε-己内酯的光交联网络合成与性能表征

采用季戊四醇(PE)引发4-甲基-ε-己内酯(MeCL)单体开环聚合,得到一系列具有四臂拓扑结构的星型聚4-甲基-ε-己内酯(PMCL),再以丙烯酰氯对PMCL末端羟基进行双键化改性,得到端基双键化星型预聚物,该预聚物与光引发剂混合后可在紫外照射下交联成型。通过1 HNMR、GPC和旋转流变仪表征了PMCL预聚物的微观结构和流变性质。研究表明:成功制备了PMCL预聚物,聚合反应可控,且通过改变臂长可调节预聚物的流变特性。此外,随着预聚物臂长的增加,交联样品的模量下降但断裂伸长率有显著提高。     

β-(2,3-环氧丙氧基)-硝酸乙酯的合成及聚合

<正> 作者曾报道了2-硝基乙基缩水甘油醚的合成及其聚合,制得距主链较远的侧链带单硝基的端羟基聚醚。上述单体与四氢呋喃的共聚物用甲苯二异氰酸酯和甘油交联后所得胶片玻璃化温度-32℃。为了进一步改进低温性能,本文研究了一种新的带硝酸酯基的三元环醚单体β-(2,3-环氧丙氧基)-硝酸乙酯的合成及其聚合。单体的合成路线如下:     

红外光谱法测定预聚物中羟基的含量

末端带有羟基的聚醚、聚酯预聚物是制备聚氨酯橡胶和塑料重要起始材料,而羟基终止的聚异戊二烯及聚丁二烯则可用以制备结构材料及火箭固体推进剂中的粘合剂。这些预聚物中羟基的含量是决定交联后形成网状结构聚合物性质的重要参数,需要建立准确测定的方法。最常用的测定方法是化学滴定法,但缺点是反应时间长,样品需要量大,预聚物不溶于水时用KOH滴定困难以及预聚物中如含有对碱敏感的基团不能应用。用IR测定预聚物中羟基,一般多用二硫化碳或四氯化碳为溶剂,使用厚的吸收池(如10厘米)测定3640cm~(-1)附近自由羟基的伸缩振动。但这种方法即使在羟基浓度很低时也     

双端羟基预聚物扩链制备高分子量聚对二氧环己酮

以1,4-丁二醇(BD)为引发剂, 辛酸亚锡为催化剂, 引发对二氧环己酮(PDO)开环聚合, 得到双端羟基型聚对二氧环己酮预聚物, 再以六亚甲基二异氰酸酯(HDI)为扩链剂制备高分子量的聚对二氧环己酮. 采用核磁共振谱对预聚物和扩链产物的结构进行了确认, 并详细考察了各种因素对扩链反应的影响. 研究结果表明, 加入适量的HDI, 于150 ℃反应60 min, 扩链效率在预聚物基础上可提高52倍, 而扩链产物的粘均分子量可达到25.7×104 g/mol.     

用DSC研究聚砜预聚物的转变

本工作用示差扫描量热法(DSC)研究了双酚A型和酚酞型两种聚砜预聚物的转变。发现两种预聚物经适当的热处理可以在玻璃化转变温度以下和以上分别产生两个转变。这两个转变可分别归之于局部分子间短程有序和长程有序的破坏。同时,得到了这两种聚砜的玻璃化温度与数均分子量的关系式。     

聚氨酯预聚物中游离甲苯二异氰酸酯的高效液相色谱测定法

聚氨酯已广泛用于泡沫塑料、涂料、油墨,绝缘材料和粘合剂等工业。其主要原料异氰酸酯单体具有毒性,从环境保护和提高产品质量角度要求聚氨酯预聚物中游离单体含量不超过1％。测定游离单体含量的方法有很多,其中气相色谱法由于汽化温度和柱温高,易使预聚物降解,结果偏高失真;ASTM法手续繁杂,适应性差。本工作建立了高效液相色谱法(HPLC)测定聚氨酯预聚物中游离甲苯二异氰酸酯(TDI)含量。并用以跟踪预聚物形成反应历程,控制产品     

ε-己内酯与D,L-丙交酯ABA型嵌段共聚物合成及作为药物载体的初步评价

“活性”中间体PCL-PLA-OAl<用环氧乙烷扩链生成含聚醚羟端基的预聚物,它与Teyssie催化剂反应后取代其中的异丙氧基生成“活性”的预聚物催化体系,进而引发CL 聚合生成PCL-PLA-PCL ABA型嵌段共聚物,它的机械性能优于AB型共聚物,断裂伸长增大约一倍,具有微观相分离结构和可控制的生物降解性能及药物释放性能。本文亦提供了内酯与交酯嵌段共聚的新途径。     

固相微萃取与气相色谱质谱联用快速监测水中的萘及硝基萘

采用涂有聚二甲基硅酮的纤维快速吸附水中的萘、１－硝基萘和２－硝基萘，再利用气相色谱的气化室温度热解析纤维上的待测物。方法简单、灵敏，不需要使用任何有机萃取溶剂。该种类型纤维可较好地吸附萘及硝基萘。加入硫酸钠可改善样品的基质，增加纤维吸附量。监测水中的萘、１－硝基萘和２－硝基萘的方法检出限可分别达０．２５、０．３０、０．２０μｇ／Ｌ。     

硝基还原酶荧光探针的研究进展

硝基还原酶是一类依赖于黄素单核苷酸或黄素腺嘌呤二核苷酸的细胞质酶,广泛存在于细菌中。肿瘤细胞缺氧通常也可导致胞内硝基还原酶增加。在电子供体如还原型烟酰胺腺嘌呤二核苷酸的存在下,硝基还原酶可以将芳香族硝基化合物有效还原为相应的氨基化合物。这种还原行为不仅用于药物的激活和芳香族硝基化合物的生物降解,同时也可用来设计含硝基的荧光探针对实体瘤细胞的缺氧状况进行检测。本文简要评述近年来硝基还原酶荧光探针的研究进展,包括基于多米诺分解反应以及荧光体上硝基直接还原为氨的反应而发展的荧光探针。     

2-氨基-3-硝基吡啶和2-氨基-5-硝基吡啶的EI/MS/MS分析

2 氨基 3 硝基吡啶和2 氨基 5 硝基吡啶的一级质谱图接近,单纯通过一级质谱图较难区分这两种异构体,利用离子阱质谱的串联质谱技术对2 氨基 3 硝基吡啶和2 氨基 5 硝基吡啶在离子阱内以He作碰撞气进行碰撞诱导裂解,所得的二级质谱图表明,两者之间存在明显的差别,可用于2 氨基 3 硝基吡啶和2 氨基 5 硝基吡啶的鉴别。     

Semi‐interpenetrating polymer networks based on polyurethane and polymethacrylate functional prepolymers: Morphology and mechanical properties in dependence of the concentration of functional groups

Grafted semi‐interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU) prepolymers with polyester soft segments and hard segments containing carboxylic functional groups as well as polymethacrylate (PM) prepolymers with tertiary amine functional groups. The dependence of morphological and mechanical properties on the concentration of functional groups was studied. The enhanced miscibility of PU and PM prepolymers was observed at concentrations of functional groups of 0.25 mmol/g of polymer and above. Despite the improved miscibility, the PM prepolymers showed a tendency toward phase separation. Because the observed glass‐transition temperature shifts of PU prepolymers indicated substantial miscibility, we ascribed this phenomenon to the presence of methyl methacrylate rich sequences in the PM prepolymer. The observed changes in mechanical properties by increasing the content of functional groups were typical for ionomers. Young's modulus increased as a result of physical interactions between functional groups. A significant drop in tensile strength was observed in IPN samples with phase‐separated PU and PM prepolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 115–123, 2002     

聚硅氧烷聚丙烯酸酯改性聚氨酯三元复合乳液中偶联剂丙烯酸羟乙酯的作用

用异佛尔酮二异氰酸酯与仲羟基封端的聚硅氧烷( PMTS)反应在PMTS分子链端引入异氰酸酯基团,然后将其与聚丙二醇反应制得聚硅氧烷改性聚氨酯( PSU)预聚体,最后加入丙烯酸酯单体(AC)通过乳液聚合制备了非偶联型聚硅氧烷聚丙烯酸酯改性聚氨酯( PSU-AC)三元复合乳液.在PSU与AC聚合时加入丙烯酸羟乙酯(HEA)...     

环四硅氧烷乳液聚合制备弹性粒子及其反应动力学的研究

用八甲基环四硅氧烷（Ｍｅ－Ｄ４）与四甲基四乙烯基环四硅氧烷（Ｖｉ－Ｄ４）乳液聚合得到了聚硅氧烷乳液，通过乙烯基的自由基聚合反应得到交联的乳胶粒子从而制备出有机硅弹性粒子．对乳液聚合的动力学和共聚物组成进行了研究，同时讨论了Ｍｅ－Ｄ４和Ｖｉ－Ｄ４残基在聚合链上的分布     

Telechelic diene prepolymers. VII. Polymerization temperature study of polyisoprenes and polychloroprenes

A study of the free-radical polymerization of isoprene and chloroprene leading to the preparation of telechelic prepolymers containing hydroxyl and carboxyl terminal groups has been carried out. The polymerization temperature was found to have a pronounced affect on the molecular weight distribution of the polyisoprenes, heterogeneity index values below 1.3 generally being found for prepolymers prepared at 60°C or below and index values higher than 1.3 being found for prepolymers prepared at higher temperatures. This change in heterogeneity index values with polymerization temperature was not observed with the polychloroprenes.     

Polymer networks containing polyether,polyamine or polysulfide chains

An overview of newer or less-known synthetic methods for the synthesis of polymer networks containing ether, amine or sulfide functions or a combination of these functional groups with other functional groups, is presented. Emphasis is given on new methods starting from well - defined telechelic prepolymers. A number of these prepolymers are obtained by living cationic systems, more particularly cationic ring-opening and cationic vinyl ether polymerizations.     

SYNTHESES AND STRUCTURES OF POLYPHENYLSILSESQUIOXANES

Phenyltrichlorosilane was hydrolyzed both ifi. toluene and in ether from which two kinds of prepolymers were obtained with different structures, molecular weights, and molecular weight distributions. Polymers were prepared from the prepolymers in various polymerization conditions. The ladderlike, branched, and crosslinked structures formed under different polymerization conditions were characterized by means of FTIR, ~1H and ~(29)Si-NMR, and elemental analysis. Azeotropic distillation of solvents and H_2O formed during polymerization was found useful in removing H_2O from the system and high molecular weight products with perfect ladderlike structure were obtained.     

由对苯二甲酰胺二醇合成聚酯酰胺及其扩链反应的研究

以N,N′-二(2-羟乙基)对苯二甲酰胺与己二酸及丁二醇缩聚,合成了同时带有端羧基与端羟基的聚酯酰胺预聚体,研究了不同扩链剂的扩链反应,获得了特性黏度达1.05 dL/g的聚酯酰胺.对预聚体及扩链后聚合物进行了红外与核磁表征,研究了聚合物的结构,并对聚合物进行了DSC与TG分析.     

Telechelic diene prepolymers. I. Hydroxyl-terminated polydienes

Telechelic prepolymers of butadiene, isoprene, and chloroprene with hydroxyl end- groups have been prepared by the solution polymerization of the dienes under free-radical initiation. 4,4′-Azobis(4-cyano-n-pentanol) was employed as the initiator. Liquid prepolymers were obtained with molecular weights of 2000 to 20,000 and with functionalities usually greater than 2. The preparative procedure and prepolymer characterization are described.     

Robust isocratic liquid chromatographic separation of functional poly(methyl methacrylate)

The separation of telechelic poly(methyl methacrylate) (PMMA) prepolymers based on the number of end-groups under critical liquid chromatography (LC) conditions has been studied using a bare-silica column, which can interact with polar functional groups. The critical solvent compositions for non-functional, mono-functional and bi-functional PMMAs were determined in normal-phase LC using mixtures of acetonitrile and dichloromethane (DCM) of varying composition as the mobile phase. The telechelic prepolymers were successfully separated according to hydroxyl (OH) functionality (with zero, one, or two OH groups, respectively) under the critical conditions, in which fast (5 min), base-line separations were obtained independent of molecular weight. Changing the column temperature, flow rate, and mobile-phase composition within a certain range did not affect the functionality separation. Therefore this isocratic LC separation method is quite robust. Evaporative light-scattering detector (ELSD) calibration curves were used for the quantitative analysis of functional PMMA prepolymers.