基于新型交联聚合物电解质的准固态染料敏化太阳能电池

采用柠檬酸(CA)交联聚乙二醇(oligo-PEG, 平均分子量M_w=200, 400, 1000, 2000), 合成具有可生物降解性能的聚柠檬酸-乙二醇(PCE)交联聚酯, 并以此为基体材料制备得到准固态的三维交联型PCE/LiI/I₂聚合物电解质. 采用红外吸收光谱(IR)、核磁共振氢谱(¹H-NMR)、扫描电镜(SEM)和Raman光谱分别对PCE基体的分子结构、聚合物电解质的微观形貌以及导电离子对的存在形式进行表征; 通过线性扫描伏安法(LSV)研究了聚合物电解质的离子扩散系数、电导率以及电池的输出电流-电压(I-V)性能. 结果表明, PEG的分子量影响PCE基体膜的微观形貌及其吸液性能, 从而影响聚合物电解质的离子导电性能及电池的光电性能: 随着PEG分子量M_w从200, 400, 1000增大到2000, PCE基体膜的结构变得疏松, 吸液率增加, 吸液溶胀后的基体中I-3的跃迁活化能降低, 导致电解质的电导率和电池的短路光电流密度随之增加; 在60 mW·cm^-2的入射光强下, 四种电解质对应电池的光电转化效率依次为3.26%、3.34%、4.26%和4.89%.     

交联聚氨酯水分散体的合成

将硅氧烷封端的含亲水基团的线性聚氨酯预聚体分散于水中 ,获得稳定的聚氨酯分散体 .由于硅氧基团水解、缩合 ,在分散体粒子内产生扩链交联反应 ,生成了交联水基聚氨酯分散体 .透射电子显微镜研究表明分散体粒径小、分布宽 .扫描电子显微镜研究了成膜结构及成膜性能与粒径的关系 .溶胀实验计算获得的两交联点之间的平均分子量与理论平均分子量相符 .研究还发现此分散体膜在干燥过程中可进一步交联 .膜的水溶胀及机械性能表明 ,此分散体具有极大的工业应用价值 .     

Synthesis and characterisation of epoxy-novolac/bismaleimide networks

Epoxy-novolac resin was modified with 1,1^′-(methylenedi-4,1-phenylene) bismaleimide (BMI), and cured with an aromatic amine. Cure behaviour of these blends was studied using differential scanning calorimetry (DSC). The thermograms indicated a unimodal exothermic peak for blends containing lower percentage of BMI. The cured blends showed much higher glass transition temperatures than that of the unmodified epoxy. Thermal stability of the cured epoxy resin was also improved with BMI addition. A homogeneous structure (with no phase separation) of the blends was confirmed both by DSC analysis and scanning electron microscopy (SEM).     

The influence of hydroxyapatite modification on the cross-linking of polydimethylsiloxane/HAp composites

Hydroxyapatite (HAp) was modified by the action of various hydrophobic agents based on silicon-containing compounds. The influence of the type of applied agent on the thermodynamic and kinetic parameters of the cross-linking of poly(dimethyl siloxane)/HAp composites was investigated. All the modified HAp particles became hydrophobic and these samples were used to synthesize the polysiloxane/hydroxyapatite composites (PDMS/HAp). The possible modes of interaction between the hydroxyapatite and hydrophobing agents were discussed. The most probable interaction between hydroxyapatite and the applied hydrophobing agents is hydrogen bonding. PDMS/HAp composites were formed directly in the cell of the DSC and cross-linking was investigated in situ. It was determined that the introduction of hydroxyapatite into polysiloxane matrices changed the enthalpy of cross-linking, as well as the activation energy of cross-linking and reaction order, while the introduction of modified HAp led to thermodynamic and kinetic parameters more similar to those of the cross-linking of unfilled elastomer.     

反应性复合乳液的合成、表征及其交联反应

利用种子半连续乳液聚合方法合成了核层或壳层带有环氧基以及壳层带有羧基的3种不同核/壳结构的乳胶粒子,通过物理共混带环氧基和羧基的乳胶粒子,得到了两种反应性复合乳液.利用透射电镜和激光动态光散射对乳胶粒子进行了表征,其粒径分布较窄,粒径分布的多分散系数为0.062,平均粒径约76 nm,乳胶粒子具有明显的核/壳结构.通过胶膜的凝胶率和膨胀率的测定和红外光谱分析对反应性复合乳液中乳胶粒子的扩散及交联反应进行了研究,并探讨了不同核壳结构复合乳液对涂膜机械性能的影响.研究表明,当反应性复合乳液中的环氧基和羧基分别分布在乳胶粒子的核层和壳层时,有利于聚合物分子链的充分扩散和化学交联反应的进行,从而提高涂膜的物理化学性能,当甲基丙烯酸缩水甘油酯(GMA)含量为10 wt%时,涂膜的拉伸强度达20.3 MPa.     

通过可控沉积和交联制备蛋白质微胶囊

通过加入反溶剂控制牛血清白蛋白(BSA)在碳酸锰微粒表面的沉积, 形成连续薄膜后交联, 去除模板后得到了尺寸均匀和分散良好的BSA中空微胶囊. 囊壁厚度可以通过滴加乙醇控制; 囊壁的截留分子量在70000—155000之间. 由于BSA含有丰富的自由羧基, 得到的微胶囊表现出pH响应性. 这种快速简便制备微胶囊的方法也可以应用于其它蛋白质及酶, 得到的生物相容的微胶囊将在药物控制释放等领域具有潜在的应用价值.     

Structural and dynamical characterization of poly-gamma-glutamic acid-based cross-linked nanoparticles

This work describes the formation of water-soluble hydrophilic nanoparticles from biosynthetic poly-γ-glutamic acid (PGA). Nanoparticles were formed by cross-linking using 2,2′-(ethylenedioxy) diethylamine in the presence of water-soluble carbodiimide. The structure was determined by nuclear magnetic resonance spectroscopy and the particle size by transmission electron microscopy (TEM), size exclusion chromatography (SEC), and dynamic light-scattering (DLS) measurements. The results from TEM, SEC, and DLS reveal that the particle size depends on the ratio of cross-linking. Particle size values measured by TEM were between 20 and 90 nm. Formation of cross-linked nanoparticles results in a dramatic viscosity drop compared to the viscosity of the corresponding solution of the parent PGA. The viscosity and DLS experiments disclose an intriguing interplay between intrachain and interchain cross-linking of the polymer chains, depending on the cross-linker density and polymer concentration. The SEC measurements show that the retention time of the major portion of particles increase because of the higher cross-linking ratio. At moderate cross-linker concentration, intramolecular cross-linking is the dominant process, whereas at higher cross-linker densities, the interpolymer cross-linking plays an important role. As a result, large clusters are also formed.     

Rheological investigation of the influence of molecular structure on natural and accelerated UV degradation of linear low density polyethylene

Metallocene and Ziegler-Natta (ZN) linear low density polyethylenes (LLDPEs) of different branch types and contents as well as linear high density polyethylene (HDPE) were exposed to natural and accelerated weather conditions. The degree of UV degradation of exposed samples was measured by rheological techniques and results were compared with unexposed polymers. Dynamic shear measurements were performed in an ARES rheometer in the linear viscoelastic range. The degree of enhancement or reduction in viscosity and elasticity was used as a measure of the degree of cross-linking or chain scission, respectively. The degradation results of LLDPE suggest that both cross-linking and chain scission are taking place. Chain scission dominated the degradation at high levels of short chain branching (SCB) and long exposure times. The degradation mechanism of m-LLDPE and ZN-LLDPE is similar; however, m-LLDPE showed a higher degradation rate than ZN-LLDPE of similar M_w and average SCB. ZN-LLDPE was found to be more stable than a similar m-LLDPE. Comonomer type had little influence on degradation. Dynamic shear rheology was very useful in revealing the influence of different molecular parameters and it exposed the degradation mechanism.     

交联型季铵聚芳醚砜阴离子交换膜的制备

采用简便环保的方法制备了具有低溶胀、高离子交换容量(IEC)的交联型季铵聚芳醚砜阴离子交换膜.随着交联度的提高,膜的吸水率和溶胀率降低,说明交联可以抑制膜的溶胀.20℃时所有交联膜的离子传导率均达0.045 S/cm以上,拉伸强度在50.1 MPa以上,表明在高IEC值下,交联膜仍具有良好的力学性能和较高的离子传导能力.同时,交联度提高会加强膜的甲醇阻隔性能.     

Development of honey hydrogel dressing for enhanced wound healing

Radiation at 25 and 50 kGy showed no effect on the acidic pH of the local honey, Gelam, and its antimicrobial property against Staphylococcus aureus but significantly reduced the viscosity. Honey stored up to 2 years at room temperature retained all the properties studied. Radiation sterilized Gelam honey significantly stimulated the rate of burn wound healing in Sprague-Dawley rats as demonstrated by the increased rate of wound contraction and gross appearance. Gelam honey attenuates wound inflammation; and re-epithelialization was well advanced compared to the treatment using silver sulphadiazine (SSD) cream. To enhance further the use of honey in wound treatment and for easy handling, Gelam honey was incorporated into our hydrogel dressing formulation, which was then cross-linked and sterilized using electron beam at 25 kGy. Hydrogel with 6% of honey was selected based on the physical appearance.