用正交设计研究PVDF/PVC/PMMA共混中空纤维膜

制备了PVDF(聚偏氟乙烯)/PVC(聚氯乙烯)/PMMA(聚甲基丙烯酸甲酯)三元共混中空纤维膜,讨论了影响膜性能的主要因素.正交实验结果表明:在PVDF/PVC/PMMA体系中,聚合物总浓度是影响膜的水通量的主要因素;PVDF浓度对膜强度影响最大;PMMA对膜的亲水性有较大的贡献.得到优化的制膜条件为:铸膜液中PVDF∶PVC∶PMMA=7∶1.2∶1.8(质量比),聚合物溶质的总质量分数为17%;添加剂吐温-80的质量分数为6%.     

溶胶-凝胶法在固体染料激光制备中的应用

固体染料激光性能优良,其制备方法有多种,溶胶-凝胶掺入法是其中较好的一种.但传统的溶胶-凝胶法还存在许多不利于制做固体染料激光的缺点.我们主要叙述了近年来发展的两种改性方法-有机改性硅酸盐法(ORMOSILS)和在溶胶-凝胶制备过程中掺入聚甲基丙烯酸甲酯(PMMA)法,并通过一系列的比较,说明有机改性硅酸盐的溶胶-凝胶法能更好的应用于固体染料激光的制备工艺中.     

真空气相沉积生长PTCDI C8 N型有机薄膜晶体管

在大气环境下N型有机薄膜晶体管(OFET)的性能不稳定,为提高晶体管在大气环境稳定性,该文分别制作了SiO2单绝缘层器件和SiO2/PMMA双绝缘层器件。采用N型新材料PTCDI-C8作为有源层,Ag作为源、漏电极,对制作的不同绝缘层的器件进行聚对二甲苯的封装,对有源层进行形貌和晶体结构分析。并进行电流-电压(I-V)曲线测试。在相同工作电压下,双绝缘层器件比单绝缘层器件具有更大的场效应迁移率、开关电流比和更小的阈值电压。     

聚甲基丙烯酸甲酯/ABS共混体系力学性能研究

采用双螺杆熔融共混工艺路线，通过选用合适牌号的聚甲基丙烯酸甲酯及ABS为基本原料，通过控制合适共混工艺条件，制备了一系列不同配比的聚甲基丙烯酸甲酯／ABS塑料合金材料。采用电子万能试验机、悬臂梁冲击实验机等测试手段对合金的力学性能进行了研究，结果表明：聚甲基丙烯酸甲酯／ABS合金材料的拉伸强度随聚甲基丙烯酸甲酯含量的增加而增大，断裂伸长率随着聚甲基丙烯酸甲酯含量的增加而减小，缺口冲击强度随聚甲基丙烯酸甲酯含量的增加而减小。     

Orthogonal ligation to spherical polymeric microparticles: Modular approaches for surface tailoring

Modular ligation strategies for the functionalization of polymeric microspheres provide new perspectives for their applications in material science. In the current trend article we highlight variable synthetic procedures for generating functional microspheres via orthogonal modular conjugation chemistries. An overview of the different surface chemistries available is provided, followed by surface-sensitive characterization techniques relevant for the microparticles. Finally, we explore future trends in modular orthogonal modification approaches on microparticles and provide an outlook on the perspectives that the field of surface-modification of polymeric microparticles holds.     

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

Electronic Structure and Ground State Properties of PMMA Polymer: II. Protection of PMMA Against Gamma Irradiation Damage

ABSTRACT

The equilibrium ground state geometric parameters of N,N,N′,N′,-tetraoxaloylsulphanilamide (Ligand I), N,N-dioxaloylbenzenesulpony-N′,N′,-dioxaloylthiocarbazide (Ligand II) and p-N,N-dioxaloylaminobenzene-N′,N′-dioxaloylbenzenesulphonyloxamide (Ligand III) as polyfunctional ligands were investigated theoretically using AM1-MO method. The expected biradicals formed after gamma radiolysis for each ligand can be detected. The radiation protection of the PMMA matrix from gamma rays, using the biradicals formed of ligands (I), (II), and (III), can be considered theoretically. The structure of the protected chains formed after recombination of two symmetric chains with biradical are theoretically modelled, because in the reaction medium the chain of PMMA formed is asymmetric. All interpretations concerning the ground state properties of the protected chains are qualitative. The thionyl, phenyl, and benzenesulphonyl biradicals are more efficient than carbonyl, thioamides, and sulphonyl biradicals as indicated from the MO-results, molecular weight investigation, and infrared spectroscopy. The protection of PMMA by the formed biradicals is confrmed by proton NMR spectroscopy.     

Comparative study of spin coated and sputtered PMMA as an etch mask material for silicon micromachining

SiO₂ and Si₃N₄, are usually used to mask the selected portions during etching of silicon in anisotropic etchants like KOH but polymers are expected to be very good alternative to SiO₂ and Si₃N₄ as masking materials for MEMS applications. An adherent spin coated PMMA layer is reported to work as a mask material. It is a low temperature process, cheaper and films can be easily deposited and removed. One of the problems in its use is its adhesion to the substrate. Our previous experience in the field made us feel that sputtered PMMA will act as better mask because of its better adhesion to silicon. In the present article, a comparative study of spin coated PMMA with sputtered PMMA as an etch mask for silicon micromachining is reported. Structural and adhesive characteristics of the films are determined and compared with those available in the literature. These films deposited on silicon wafer were exposed to anisotropic etchant, KOH, to estimate the masking behavior. The maximum masking time of 32 min in 20 wt.% KOH at 80 °C was obtained for spin coated PMMA samples, which were prebaked at 90 °C. Masking time of sputter deposited PMMA films was found to be 300 min under similar conditions such as 20 wt.% KOH at 80 °C. This masking time is sufficient for fabrication of various MEMS structures, thus indicating candidature of sputtered PMMA as masking material. Various properties of the films are discussed and compared with the ones obtained through literature.     

组分玻璃化温度对共混高聚物α内耗峰的影响

选择两组分玻璃化温度较远的PEO/PMMA以及玻璃化温度相近的SAN/PMMA两个均相共混体系为研究对象 ,考察了组分组成对共混物α内耗峰峰高、峰宽以及温频关系的影响 .结果表明 ,共混物α内耗峰峰高及温频关系介于纯组分之间 ,随组分组成有规律地变化 ;PEO/PMMA体系的弛豫谱明显地比纯组分的宽 ,而SAN/PMMA体系的弛豫谱宽度跟纯组分的相差不多 .认为由于PEO/PMMA两组分的玻璃化温度相差甚远 ,组成涨落造成玻璃化温度及弛豫时间的分布变宽 ,因而弛豫谱也很宽     

Impedance studies on plasticized PMMA-LiX [X: CF3SO3, N(CF3SO2)2−] polymer electrolytes

Plasticized polymer electrolytes composed of poly(methylmethacrylate) (PMMA) as the host, propylene carbonate (PC) or ethylene carbonate (EC) as a plasticizer and LiX (X: CF₃SO₃⁻ or N(CF₃SO₂)₂⁻) as a salt were prepared by the solution cast technique. Impedance spectroscopy was performed in the temperature range between 303 and 383 K. In this paper, we report the electrical properties of polymer electrolytes with different lithium salts and plasticizers. The polymer electrolytes investigated exhibited high ionic conductivity at room temperature in the range of 10^− 6 to 10^− 4 S cm^− 1. The temperature dependence studies showed that the samples were ionic conductors and seemed to obey the Vogel-Tamman-Fulcher (VTF) rule. FTIR spectroscopy studies confirmed the polymer-salt interaction.