胶粒为“Salami”结构的PMMA/SiPUA乳液与膜性能研究

采用两步法,先以六亚甲基二异氰酸酯(HDI)、聚醚二元醇(N210)、端羟丙基硅油(HPMS)、端羟基丙烯酸树脂(PA-OH)为主要原料,合成了含硅聚氨酯-丙烯酸酯(Si PUA)种子乳液,然后在Si PUA乳胶粒内引入甲基丙烯酸甲酯(MMA),通过原位自由基共聚合,构筑了以Si PUA为壳,聚甲基丙烯酸甲酯(PMMA)为多核的"Salami"结构乳胶粒(PMMA/Si PUA).FTIR和DSC测试表明,聚氨酯、有机硅与丙烯酸酯发生反应,并确认了PMMA的生成;TEM结果显示,PMMA/Si PUA乳胶粒子具有"Salami"结构;随着Si PUA中HPMS含量的增加,PMMA/Si PUA乳胶粒子的粒径先增加后减小,粒径分布则从单峰窄分布变化到双峰宽分布,其乳液涂膜的水接触角呈现先增加后减小的趋势,但膜的吸水率则逐渐减小;与Si PUA相比,PMMA/Si PUA涂膜的透明性有一定下降,相分离程度增加;动态流变测试显示,PMMA/Si PUA涂膜中PMMA的存在,提高了其模量和黏度.当Si PUA中HPMS含量为10 wt%,核/壳质量比m(PMMA)/m(Si PUA)=0.5时,PMMA/Si PUA乳液的粒径较小,且为单峰分布,其涂膜的耐水性和耐高温性能较好.     

Preparation and performance analysis of PE-supported P(AN-co-MMA) gel polymer electrolyte for lithium ion battery application

Copolymer, poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), was synthesized by solution polymerization with different mole ratios of monomers, acrylonitrile (AN) and methyl methacrylate (MMA). Polyethylene (PE) supported copolymer and gel polymer electrolyte (GPE) were prepared with this copolymer and their performances were characterized with FTIR, TGA, SEM, and electrochemical methods. It is found that the GPE using the PE-supported copolymer with AN to MMA = 4:1 (mole) exhibits an ionic conductivity of 2.06 × 10⁻³ S cm⁻¹ at room temperature. The copolymer is stable up to 270 °C. The PE-supported copolymer shows a cross-linked porous structure and has 150 wt% of electrolyte uptake. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 5.5 V (vs. Li/Li⁺). With the application of the PE-supported GPE in lithium ion battery, the battery shows its good rate and initial discharge capacity and cyclic stability.     

PMMA／石墨导电复合材料的制备与表征

以可膨化石墨为原料,高温处理得到膨化石墨,再经过超声处理,得到纳米薄片石墨。将得到的纳米薄片石墨与甲基丙烯酸甲酯单体在超声作用下预聚,灌模,得到块状的聚甲基丙烯酸甲酯(PMMA)/石墨复合材料。用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、选区电子衍射SAD、红外、热重等分析仪器表征了纳米石墨薄片及PMMA/石墨复合材料。测试了复合材料的力学、电学性能,发现在室温下该复合材料的渗滤阀值为1.3%(wt),且保证石墨含量在1.4%(wt)时,即可保证复合材料具有良好的电学和力学性能。     

Synthesis of sub-micronic and nanometric PMMA particles via emulsion polymerization assisted by ultrasound: Process flow sheet and characterization

PMMA particle synthesis was performed from MMA (methyl methacrylate) and water mixtures, exposed to different ultrasonic systems and frequencies. The sonication sequence was 20 kHz → 580 kHz → 858 kHz → 1138 kHz, and the solution was sampled after each irradiation step for polymerization. Effects of sonication parameters (time, power), polymerization method (thermo-initiated or photo-initiated), use of small amounts of surfactant (Triton X-100™ or Tween® 20) and initial MMA quantity were investigated on particle size and synthesis yields. Particle size and size distribution were measured by DLS (Dynamic Light Scattering), and confirmed via SEM (Scanning Electron Microscopy) images. Synthesis yield was calculated using the dry weight method. Particle composition was estimated using FTIR (Fourier Transform Infra-Red) spectroscopy. PMMA (polymethylmethacrylate) monodispersed particles were successfully synthesized, with a possibility of control in the 78–310 nm size range. These sized-controlled particles were synthesized with a 7.5–85% synthesis yield (corresponding to 7.5–40 g/L particle solid content), depending on operational parameters. Furthermore, a trade-off between particle size and synthesis yield can be proposed: 20 kHz → 10 min waiting time → 580 kHz → 858 kHz leading to 90 nm particles diameter with 72% yield in less than 40 min for the whole sequence. Thus, the synthesis under ultrasound can be found easy to implement and time efficient, ensuring the success of the scale-up approach and opening up industrial applications for this type of polymeric particles.     

Fluorination of polymethylmethaacrylate with tetrafluoroethane using DC glow discharge plasma

Fluorination of polymer surfaces has technological applications in various fields such as microelectronics, biomaterials, textile, packing, etc. In this study PMMA surfaces were fluorinated using DC glow discharge plasma. Tetrafluoroethane was used as the fluorinating agent. On the fluorinated PMMA surface, static water contact angle, surface energy, optical transmittance (UV-vis), XPS and AFM analyses were carried out. After the fluorination PMMA surface becomes hydrophobic with water contact angle of 107° without losing optical transparency. Surface energy of fluorine plasma-treated PMMA decreased from 35 mJ/cm² to 21.2 mJ/cm². RMS roughness of the fluorinated surface was 4.01 nm and XPS studies revealed the formation of C-CF_x and CF₃ groups on the PMMA surface.     

Low‐energy excitations in stressed poly(methyl methacrylate)

Raman study of flexure stressed poly(methyl methacrylate) (PMMA) plates at the frequency range of libration mode (80 cm⁻¹), boson peak (14 cm⁻¹), and quasi‐elastic light scattering (QLS) (below 20 cm⁻¹) is presented. The reversible changes in the vicinity of the Rayleigh line were attributed to partial disturbance of the midrange order due to stress‐induced redistribution of random fluctuations of orientation. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1133–1136, 2000     

Microscopic Kinetics in Poly(Methyl Methacrylate) Exposed to a Single Ultra-Short XUV/X-ray Laser Pulse

We study the behavior of poly(methyl methacrylate) (PMMA) exposed to femtosecond pulses of extreme ultraviolet and X-ray laser radiation in the single-shot damage regime. The employed microscopic simulation traces induced electron cascades, the thermal energy exchange of electrons with atoms, nonthermal modification of the interatomic potential, and a triggered atomic response. We identify that the nonthermal hydrogen decoupling triggers ultrafast fragmentation of PMMA strains at the absorbed threshold dose of ~0.07 eV/atom. At higher doses, more hydrogen atoms detach from their parental molecules, which, at the dose of ~0.5 eV/atom, leads to a complete separation of hydrogens from carbon and oxygen atoms and fragmentation of MMA molecules. At the dose of ~0.7 eV/atom, the band gap completely collapses indicating that a metallic liquid is formed with complete atomic disorder. An estimated single-shot ablation threshold and a crater depth as functions of fluence agree well with the experimental data collected.     

PM567-Doped solid dye lasers based on PMMA

Polymers are a kind of attractive hosts for laser dyes due to their high transparency in both pumping and lasing ranges and superior optical homogeneity. In this paper solid dye samples based on polymethyl methacrylate (PMMA) doped with different concentrations of 1, 3, 5, 7, 8 -pentamethyl-2, 6-diethylpyrromethene-BF$_{2 }$ (PM567) are prepared. The absorption, fluorescence and lasing spectra of the samples are obtained. Wide absorption and fluorescence bands are obtained and a red shift of the maxima of the lasing emission spectra is observed. With the second-harmonic generation of Q-switched Nd:YAG laser (532\,nm, $\sim $20\,ns) pumping the samples longitudinally, the slope efficiencies of the samples are obtained. There is an optimal dye concentration for the highest slope efficiency when the pumping energy is lower than some typical value ($\sim $250\,mJ), and the highest slope efficiency 35.6{\%} is obtained in the sample with a dye concentration of $2\times10^{ - 4}$\,mol/L. Pumping the samples at a rate of 10Hz with a pulse energy as high as 200\,mJ (the fluence is 0.2\,J/cm$^{2})$, the output energy drops to one-half of its initial value after approximate 15500 pulses and the normalized photostability is 5.17\,GJ/mol. A kind of solid dye laser which could have some applications is built.     

流体驱动智能电动控制仪用于PMMA微流控芯片电渗流的测量

采用自制的流体驱动智能电动控制仪作为电渗驱动控制源,结合电流跟踪法测量聚甲基丙烯酸甲酯(PMMA)芯片的电渗流,讨论了PMMA形成电渗的机理,给出了PMMA芯片通道电场强度与电渗速度的关系曲线。     

一种基于光学偏置的新型Math—Zehnder调制器结构设计

设计了一种基于光学偏置并以有机聚合物PMMA／DRI作为光波导材料的新型Mach-Zehdner调制器。利用有效折射率法（EIM）,分析了脊波导的有效折射率随脊波导结构参数变化情况,包括脊宽训、脊高b和芯层厚度d,以及上下包层厚度。采用微带线单电极调制方式结合脊波导的结构设计,实现了微波和光波的速率匹配。针对优化的结构参数,采用BPM方法进行光场和功率传输的模拟仿真,完成了非等臂Math—Zehnder调制器的结构设计,实现了两臂89．84。的初始相位差,消光比约为27dB。