计算机辅助三聚氰胺分子印迹聚合物的制备

以三聚氰胺(MAM)为印迹分子,丙烯酰胺(AM)、甲基丙烯酸(MAA)、N,N-亚甲基双丙烯酰胺(MBA)和衣康酸(IA)为功能单体,二乙烯基苯(DVB)、乙二醇双甲基丙烯酸酯(EGDMA)和三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂,采用量子化学密度泛函理论的长程校正方法模拟并探讨了MAM与4种功能单体的成键作用位点、成键数目、印迹反应摩尔比及印迹作用机理.依据结合能(ΔE)优化了功能单体和交联剂,并借助分子中原子理论(AIM)揭示了MAM与功能单体印迹作用的本质.计算结果表明,MAM通过氢键与4种功能单体以摩尔比1∶6进行印迹聚合,其中IA与MAM形成的复合物结合能最低,结构最稳定;与TRIM和EGDMA交联剂相比,DVB与MAM结合能最低,更适合作为MAM-IA印迹聚合物的交联剂.采用沉淀聚合法合成MAM分子印迹聚合物(MAM-MIPs)并测定其吸附性,当MAM与IA印迹摩尔反应比为1∶6时,以DVB为交联剂时制备的MAM-MIPs吸附性最好,其微球平均粒径为195 nm;Scatchard分析结果表明,在所研究的浓度范围内MIPs对印迹分子MAM的结合位点是等价的,其最大表观吸附量Qmax为20.79mg/g,离解平衡常数Kd为58.82 mg/L;与环丙氨嗪(CYR)、三聚氰酸(CYA)和三聚硫氰酸(TRI)在牛奶中的吸附量相比,MAM-MIPs对MAM表现出较强的特异吸附能力.     

Response of Cellulose detectors to different doses of 62?MeV protons

Optical and thermal responses of two cellulose detectors, Cellulose triacetate (Triafol-TN) and Cellulose acetate butyrate (Triafol-BN), to four different doses of 62 MeV protons were studied using spectroscopic, thermal and track-etching techniques. The spectroscopic analysis revealed that though the optical band-gap in the polymers was affected by proton irradiation, the polymers showed high resistance against any major structural modification by radiation. The thermal stability of the polymers was found to be affected by proton irradiation. The activation energy of etching was found to be almost constant for both the polymers even after irradiation. It is hoped that the findings in this work would be of significant relevance to material science and applications of polymers.     

Unusual in vitro degradation behavior of physically cross-linked liposome gel network

In this study, the in vitro degradation behavior of self-assembled liposome gel was investigated, especially in comparison with rheological studies. The liposome gel, physically cross-linked by hydrophobic interactions, was obtained by mixing liposome solution with cholesterol-end capped polyethylene glycol. The liposome gel was found to have rheological behavior similar to that of Maxwell model. The plateau modulus of the liposome gel, an important value to reflect the effective cross-linking density among the network, was dependent on both the liposome concentration and the polymer concentration. When the liposome gels were exposed to an aqueous solution, they first showed a period of swelling phase due to adsorption of water and then a dissolution phase began, leading to the full degradation of the network. The liposome gel with higher plateau modulus (i.e. higher effective cross-linking density) was found to degrade more slowly, indicating that the degradation behavior of the gel was closely related with the rheological properties. In order to study the gel degradation mechanism more directly, dextran blue-loaded liposome gel was prepared. In the initial period of the liposome gel exposure to the aqueous solution, the dextran blue release was of Fickian diffusion transport behavior. After that period, the release mechanism was found to be of Super Case II transport, which was gel matrix relaxation controlled.     

聚苯硫醚热交联特性研究进展

聚苯硫醚是一种具有典型交联特性的半结晶型热塑性聚合物,在不同气氛条件下进行热处理会发生不同程度的热交联、链增长、氧化交联和氧化反应,热处理后的PPS树脂分子量增加,热稳定性提高,结晶性能也会发生变化。主要围绕PPS树脂热交联处理的机理研究及其在工程上的应用,重点阐述了不同热处理条件对PPS树脂性能的影响及其与工程应用的结合。对PPS树脂后处理过程中存在的问题进行总结,提出了将热交联处理和增韧结合起来同步完成的研究思路。     

侧链含萘可交联聚芳醚酮的合成及性能

以4,4'-二羟基苯基正戊酸和4,4'-二氟二苯酮为原料, 二甲基亚砜(DMSO)为溶剂, 采用亲核取代反应合成侧基含羧基的聚芳醚酮均聚物, 进一步与1-萘酚和2-萘酚接枝制备新型含萘可交联聚芳醚酮. 用核磁共振(NMR)、红外光谱(FTIR)、示差扫描量热(DSC)和热重分析(TGA)表征其结构和性能, 含萘聚芳醚酮在常用有机溶剂如N,N-二甲基乙酰胺(DMAc)、DMSO, 四氢呋喃(THF)中有良好的溶解性, 并具有很好的成膜性. DSC测试结果显示, 在170℃热处理2 h的交联聚合物的玻璃化转变温度(T_g)提高40℃. TGA数据显示接枝后的聚合物的5%热失重温度提高40~50℃, 证明其发生交联反应. 结果表明, 新型含萘可交联聚芳醚酮具有热固性树脂的耐溶剂和耐高温特性, 进一步拓宽了聚芳醚酮的应用前景.     

丙烯酸共聚物囊壁的正十八烷微胶囊的制备和性能表征

以二丙烯酸1,4-丁二醇酯为交联剂, 成功制备了甲基丙烯酸甲酯-甲基丙烯酸共聚物为壁材, 正十八烷为囊芯的相变材料微胶囊. 采用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TG)分别考察了单体与芯材投料比、单体浓度和交联剂的含量对微胶囊形貌、相变热性能、热稳定性能的影响. 实验结果表明: 随着单体与芯材投料比或单体浓度的增加, 微胶囊表面均变得致密, 壁厚增加; 随着交联剂含量的增加, 微胶囊的表面变得更加致密光滑, 热稳定性显著增强; 随着单体与芯材投料比的增大, 微胶囊热焓值减小, 被包裹的囊芯含量减少.     

Mechanical Properties and Network Structure of Hydrophobic Association Hydrogels Prepared from Octylphenol Polyoxyethylene(7) Acrylate and Sodium Dodecyl Sulfate

Hydrophobic association hydrogels(HA-gels) with high mechanical strength were prepared by free radical micellar copolymerization in aqueous solutions of acrylamide(AM), anion surfactant sodium dodecyl sulfate(SDS) and a small amount of hydrophobic monomer octylphenol polyoxyethylene(7) acrylate(OP-7-AC). We found that the molar ratio of SDS to OP-7-AC has a great effect on the tensile strength and other mechanical property parameters. The best ratio point R' was determined. On the basis of Mooney theory and statistical theory, the critical tensile ratios and critical tensile strengths of the hydrogels were obtained, elastic parameters C₁ and C₂ were calculated via uniaxial tensile equation and structural parameters, such as the effective network chain density and the averaged molecular weight of the chain between cross-linking points of all the hydrogels were evaluated. The results indicate that the variation of mechanical property parameters depends on the number of effective cross-linking points and the match degree of long and short chains.     

粘度法对可溶解的聚氨酯交联大分子的溶液行为的研究

通过体积稀释法测定可溶性交联大分子溶液的特性粘数随交联度、浓度和时间的变化,发现聚氨酯可溶性交联大分子在溶液中出现与线型和支化型高分子溶液不一样的粘度行为.本文根据聚氨酯的特殊的结构对这些异常现象进行了解释.     

Synthesis of multi-functional epoxides derived from limonene oxide and its application to the network polymers

Bio-based multi-functional epoxides (1) such as bis-, tri-, and tetra-epoxides were synthesized by ene-thiol reactions between limonene oxide and polyhydric thiols. A cross-linking reaction of 1 with branched polyethyleneimine (BPEI) afforded the corresponding network polymers 2 with relatively high thermal resistance in high yields.     

层状α-Zr(HPO_4)_2·H_2O交联过程的研究

以有机硅CH_3Si(OC_2H_5)_3和NH_2(CH_2)_3Si(OC_2H_5)_3为交联剂,对层状化合物α-Zr(HPO_4)_2·H_2O进行交联,经灼烧分别得到2种不同层间距的层柱型分子筛SiO_2-Zr(HPO_4)_2。用XRD、GC、NMR等方法对交联反应过程进行了研究,结果表明,交联剂在反应过程中发生水解、缩聚。某种聚合态硅选择性地嵌入α-Zr(HPO_4)_2·H_2O层间。