分离丙烯/丙烷的超薄聚电解质中空纤维复合膜的制备

以含二氮杂萘联苯结构的聚芳醚砜酮PPESK(Tg为263~305℃)为膜材料,以干-湿纺丝技术制备基膜,外涂法涂覆聚电解质(聚乙烯基吡咯烷酮PVP)并络合Ag 离子,制备了超薄皮层中空纤维复合膜,皮层厚度约为1μm。研究了复合膜聚电解质涂层PVP质量分数、Ag 含量、气体压力差、测试温度和不同过渡金属离子等对复合膜丙烯/丙烷分离性能的影响。结果表明,在压力为200kPa、温度为23℃下,当PVP质量分数为10%、n(Ag )∶n(CO)=1∶1的条件下,复合膜对丙烯渗透率可达16.32GPU,分离系数为4.79。     

槲皮素金属配位印迹聚合物膜的制备及性能研究

以中药活性成分黄酮类化合物槲皮素与Zn(II)的配合物为模板, 以4-乙烯基吡啶为功能单体, 乙二醇二甲基丙烯酸酯为交联剂, 水溶性线性聚合物聚乙二醇(PEG, M_w＝600)为添加剂, 利用分子印迹技术紫外光引发原位聚合的方法制备了带支撑的锌离子配位分子印迹聚合物膜. 使用扫描电镜测定了不同PEG用量下膜的表面形貌. 通过膜渗透实验考察了PEG含量对金属配位印迹膜渗透速率的影响, 系列印迹聚合物膜的识别体系及对不同底物的渗透选择性, 同时考察了阳离子和阴离子对印迹膜渗透模板分子的影响. 实验结果表明: 制膜过程中水溶性线性聚合物PEG的加入可以明显改善膜的透过性能|槲皮素-Zn(II)模板印迹聚合物膜对槲皮素表现出明显的渗透选择性, 对槲皮素结构类似物芦丁和柚皮素的渗透选择性较差|且该金属配位印迹聚合物膜对不同阳离子和阴离子也都表现出较好的选择识别作用.     

A New Criterion for Brittle-Ductile Transition of Polymer Blends

The T_c criterion was first used by S. Wu for characterizing the brittleductile (B-D) transition of N6/EPDM blends. But in this paper, a new criterion which is based on the stress analysis of blends is proposed to characterize the B-D transitions of blends, namely, A criterionV_(fc) and d_c are the critical volume fractions and particle size of dispersed particles in blends, respectively. For given blends, A is independent of the morphology of dispersed phase and is only the characteristic parameter of matrix. The B-D transitions of different blends, including polar N6/EPDM blends, nonpolar PP/EPDM blends and PE/CaCO_3 composites, were manipulated with A criterion and satisfactory results were obtained. In addition, a new master curve for the impact strength of PP/EPDM blends versus V_f~2/d was obtained. The results showed that A criterion is more suitable than T_c criterion for characterizing the B-D transition of blends.     

Relations between Glass Transition Temperatures in Miscible Polymer Blends and Composition: From Volume to Mass Fractions

The use of volume fractions in the empirical mixing laws to predict the glass transition temperatures (Tg) of polymer blends provides good agreement with experimental values, even for polymer systems with different densities. No adjustment parameter is therefore required whereas Gordon-Taylor and Kwei equations based on weight fractions need the use of a fitting parameter which has to be determined from experimental data. This assumption was validated from Tg measurements through DSC experiments conducted on PMMA /PVDF blends which have significantly different densities.     

NMR Investigations of Temperature-Induced Phase Transition in Aqueous Polymer Solutions

The different dynamics of polymer segments forming phase-separated globular structures in aqueous (D₂O) solutions affects both the shape of NMR spectra and NMR relaxation times of polymer and solvent. Two types of the approach are discussed. The first one is based on the reduction of integrated intensities of polymer NMR lines in high-resolution NMR spectra in the system undergoing the coil-globule phase transition. The fraction p of phase-separated units (units with significantly reduced mobility) and subsequently, e.g., thermodynamic parameters ΔH and ΔS characterizing the coil-globule phase transition can be determined. The second approach is based on measurements of ¹H NMR relaxation times of water (HDO) which provide information on behaviour of water during phase transition. The power of both approaches is demonstrated on results obtained with solutions of several thermoresponsive homopolymers and copolymers.     

用于柔性超级电容器的凝胶聚合物电解质膜的制备

以聚乙烯吡咯烷酮(PVP)提高戊二醛(GA)交联的聚乙烯醇(PVA)凝胶在1 mol/L的H2SO4溶液中的溶胀度,制备出一种用于柔性超级电容器的凝胶聚合物电解质膜,并对该电解质膜的结构、形貌、溶胀度、力学性能和电导率等进行了表征.在此基础上,组装了一种基于石墨烯电极的柔性超级电容器.结果表明:随着PVP用量的增加,膜孔数量增多且孔径增大,溶胀度增加,电导率提高,但力学强度下降.电解质膜中PVP质量分数为20％时,所组装的柔性超级电容器的比电容为111 F/g,其电化学性能的温度依赖性较低,稳定性较好.     

高分子辅助倒相法制备聚乙烯醇多孔膜

采用高分子辅助倒相法制香了多孔的ＰＶＡ－ＰＶＡｃ膜,并测得其孔隙率,最大孔径,平均孔径及孔径分布。研究了影响这些孔特性的各种因素,在扫描电镜下考察了多孔膜的微观形态,制得的膜孔隙率可调节,孔径分布窄。     

The Distribution of Glass Transition Temperatures in Ultrathin Polymer Films Controlled by Segment Density or Interfacial Interaction

Nowadays, the microscopic mechanism controlling the distribution of local glass transition temperatures (T_gs) across thin polymer films is still unclear and thus large‐scale applications of polymer films are restricted. Dynamic Monte Carlo simulations are performed to investigate the key factors dominating the distribution of layer T_gs in two kinds of capped ultrathin films with and without attractive polymer–substrate interactions, respectively. For the film without polymer–substrate interaction, the interfacial layer T_g is lower than the middle layer T_g. Additionally, the layer T_gs and the layer segment densities below T_g are linearly correlated, indicating that polymer density determines the distribution of layer T_gs. However, for the films with polymer–substrate interactions, the interfacial layer T_g increases dramatically with the raise of interfacial interactions, while the middle layer T_g decreases slightly. The interfacial layer T_g is proportional to the strength of interfacial interaction, while the middle layer T_g is linearly correlated with the segment density of the middle layer below T_g. Namely, interfacial interaction is the main factor dominating the interfacial layer T_g, while segment density controls the middle layer T_g.

     

直接甲醇燃料电池用阻醇质子导电聚乙烯醇-聚苯乙烯磺酸共混膜

制备了聚乙烯醇 (PVA)与聚苯乙烯磺酸 (PSSA)的共混膜 ,并研究了膜的组成、热处理温度、甲醇水溶液浓度等对膜电导率和甲醇透过率的影响。与目前普遍使用的NafionTM膜相比 ,这种由阻醇材料PVA与离子交换材料PSSA共混后形成的聚合物膜既能提高阻醇性能 ,又具有一定的电导率。一种以聚苯乙烯磺酸含量为 17%的膜 ,其电导率可达 3× 10 -3 S·cm-1,但甲醇透过率P仅为 2× 10 -8cm2 ·s-1。如果以σ/P为综合指标 ,则此膜的综合性能比NafionTM膜高约 4 0倍     

高分子物理课程中影响高分子柔顺性因素的教学实践

针对高分子物理课程中影响高分子链柔顺性的高分子链结构方面因素的讲授,结合不同高分子材料的用途,形象地说明了高分子链柔顺性对高分子材料性能的影响,使学生真切地了解到高分子链的柔顺性决定了高分子材料的不同用途,这种理论联系实际的教学方法避免了抽象的死记硬背,可以加深学生的感性认识,取得了良好的教学效果。     

高聚物从高弹态到流体态的转变

将高聚物由高弹态转变为流体态的转变温度命名为流动温度Tf,该转变温度与高聚物分子量密切相关.在高聚物从高弹态转变为流体态的研究中,由于T1.1的概念忽视对高聚物分子量的依赖性,因此采用Tf的概念更为合理.本文对高聚物的流动温度Tf的讨论涉及高聚物温度-形变曲线、高弹态温区、高聚物熔体剪切粘度.从高聚物凝聚态观点来看,高聚物熔体中凝聚缠结网络中的凝聚结点是分子链的局部向列相互作用使链单元间产生平行凝聚而形成的,而高聚物从高弹态到流体态的转变正是反映了高聚物熔体中凝聚缠结网络的物理交联点,即凝聚结点状态的变化.高聚物熔体可以流动,说明熔体中凝聚网络中的凝聚结点至少是可以在瞬间内打开的,升温使凝聚结点的解凝聚状态存在的时间加长,凝聚状态存在时间减短,当升高到某一温度时,在凝聚结点解凝聚状态的时间内,分子链通过内旋转使质量中心在外加力的方向上可以发生位移,此时高聚物从高弹态转变为流体态,而此时的温度就是流动温度Tf.对高聚物流体弛豫网络的研究,是一个很有前景的研究课题.     

侧链液晶聚合物相转变点的分子动力学模拟

液晶基本上可分为３类：向列型液晶、近晶型液晶和胆甾型液晶［１］．液晶材料的相转变温度的预测对选择和设计液晶材料具有非常重要的作用．本文用分子动力学模拟法对聚［ω－（４′－甲氧基联苯－４－氧基）己基］甲基丙烯酸酯（ＰＭ６ＭＰＰ）单链分子进行了研究,模拟...     

Adsorption Transition of a Polymer Chain at a Weakly Attractive Surface: Monte Carlo Simulation of Off‐Lattice Models

A bead‐spring model of a polymer chain with one end attached to a wall is studied by Monte Carlo simulations for chain lengths 16 ≤ N ≤ 256. Two types of adsorption potentials, 9‐3 and 10‐4 Lennard‐Jones (LJ) potentials, between the effective monomers and the wall are assumed. For both cases the adsorption transition where the chain changes its asymptotic statistical properties from a three‐dimensional to a two‐dimensional configuration is located using a scaling analysis. It is shown that the crossover exponent φ = 0.50 ± 0.02 is the same for both LJ potentials. This value is compatible with recent theoretical predictions and simulation results for lattice models with short‐range wall potentials. The results of our study support the expectation that the exponents describing the adsorption transition are universal, i.e., they are not influenced by the precise form and the long‐range character of the adsorption potentials used. The technical aspects of the simulations (which use configurational bias methods as well as histogram re‐weighting) are also carefully discussed.

Snapshot pictures of a bead‐spring model of a polymer chain with N = 256 beads with one end anchored on the surface: (a)“mushroom configuration”, (b) ε_a ≈ ε_w at the adsorption transition, and (c)“pancake configuration” of a strongly adsorbed chain.     

高稳定性金属有机配位聚合物膜的制备及二甲苯分离性能

以常见的多孔二氧化硅为载体, 采用晶种-二次生长法在溶剂热条件下制备了高稳定性的金属有机配位聚合物膜材料. 通过X射线衍射、 扫描电子显微镜、 单组分气体透过率和二甲苯同分异构体分离等测试手段对材料的结构、 形貌和性质等进行了表征. 二甲苯同分异构体的渗透汽化分离结果表明, 这种多孔膜材料对二甲苯混合物具有选择性吸附分离的性质. 进一步通过热处理、 超声处理和性能的重复表征, 证明了该膜材料具有优良的热稳定性和机械稳定性, 适于实际应用.     

密胺苯二醛多孔聚合物/聚二甲基硅氧烷混合基质膜的制备及气体分离性能

以溶液复合成膜法制备了密胺苯二醛多孔聚合物(MA)/聚二甲基硅氧烷(PDMS)混合基质膜,利用扫描电镜(SEM)表征了混合基质膜的形貌。考察了不同MA用量下MA/PDMS混合基质膜的气体分离性能,结果表明,MA的加入可以在提高PDMS膜渗透系数的同时提高CO_2气体分离选择性;随着混合基质膜中MA含量的增加,混合基质膜的渗透系数均明显提高,气体分离选择性则先增大后减小。双组分混合气体分离测试结果表明,MA/PDMS(1.2%(w,质量分数))混合基质膜对CO_2/N_2和CO_2/CH_4的分离选择性分别是19.2和6.0,CO_2的渗透系数达到8100Barrer,均高于纯PDMS膜。MA/PDMS(1.2%(w))混合基质膜对CO_2/N_2混合气的分离性能突破了Robeson上限。     

Stiffening of Semirigid Polymer Chains Before the Isotropic-Aniostropic Transition

Introduction　　 The conformation of the synthetic polypeptide such as poly(γ-benzyl L-glutamate)(PBLG) or poly(β-phenethyl L-aspartate) (PPLA) is maintained in theα-helix in numerousorganic solvents that supports the intramolecular hydrogen bonding.Above a critical volumefraction of a polymer,the randomness of the orientation along the long axes of the macro-molecule is lost and a lyotropic liquid crystal is formed[1 ] .　　 If the polypeptide is dissolved in a binary solvent mixture c…     

烟碱分子烙印聚合物的吸附特性

利用分子烙印技术，以烟碱为烙印分子，甲基丙烯酸(MAA)为功能单体，乙二醇二甲基丙烯酸酯(EDMA)为交联剂，合成了对烟碱具有特异性作用的分子烙印聚合物P(Nic)；通过平衡吸附实验，评价了其对烟碱的亲和力和选择性。与非烙印聚合物相比，P(Nic)对烟碱表现了很高的亲和力；Scatchard分析表明在P(Nic)中存在对烟碱有不同的亲和力的两类作用位点。通过与氨基吡啶类物质在P(Nic)上的吸附行为比较，表明P(Nic)对烟碱具有很好的选择性。本工作证明了用P(Nic)作为固相萃取(SPE)材料选择性地从烟草烟雾中提取烟碱的可能性。