聚异戊二烯-丝胶接枝共聚物的合成与性能研究

以异丙苯过氧化氢和四乙烯五胺为氧化还原对引发剂,通过乳液聚合合成了聚异戊二烯接枝丝胶乳液(PL-g-SS),其结构和性能经NMR,TEM及激光粒度分析表征.结果表明:丝胶成功地接枝到聚异戊二烯上;PL-g-SS双亲纳米微球具有明显的PL为核,SS为壳的核壳结构,平均粒径48nm,且粒径分布较为均匀.采用杂凝聚法将PL-...     

新型核壳结构水凝胶的合成与表征

以羟丙基纤维素为模板,在水溶液中合成了不含表面活性剂的聚甲基丙烯酸（PMAA）纳米水凝胶。再以该PMAA纳米水凝胶为模板,合成了具有pH和温度双重敏感的聚甲基丙烯酸/聚N-异丙基丙烯酰胺（PMAA-PNIPA）核壳结构纳米水凝胶。对纳米水凝胶的形态、结构、pH以及温度敏感性的表征结果表明,纳米水凝胶粒径为338.8～407.9 nm,并随交联剂用量的增加而减小,其体积相转变具有良好的pH及温度响应性,这种绿色合成的生物相容性新型核壳结构纳米水凝胶具有极为广泛的应用前景。     

PMMA-PAN核壳结构复合乳胶的制备与表征

采用疏水引发剂引发的半连续无皂乳液聚合法,合成了Z均流体力学直径约70nm的聚甲基丙烯酸甲酯(PMMA)纳米乳胶。以PMMA纳米乳胶为种子,采用疏水引发剂引发的种子乳液聚合法,制备了PMMA-聚丙烯腈(PAN)核壳结构复合乳胶。采用动态光散射、傅里叶红外光谱、扫描电镜和透射电镜表征了各种乳胶粒的组成、尺寸、结构和微观形态。研究了反应温度、单体用量和表面活性剂用量对PMMA-PAN复合乳胶粒的结构和形态的影响。结果表明:PMMAPAN复合乳胶粒为核壳结构,其壳层厚度可通过改变单体用量进行调整。     

聚苯乙烯/Ag核壳结构纳米微粒的制备及表征

用种子乳液聚合法合成了聚苯乙烯（PS）/Ag复合纳米粒子,进一步利用分步聚合技术实现了聚甲基丙烯酸甲酯(PMMA)在微球表面功能化,分别用TEM、XRD、TG-DTA及FT-IR对其结构和形貌进行了表征,并考察了其摩擦学性能.结果表明,在所选择的实验条件下,合成了以Ag纳米微粒为核,PS、PMMA为壳层的核壳结构复合纳米微球,其中Ag纳米核平均粒径约12 nm,复合微球粒径约25 nm,颗粒较均匀并且在有机溶剂中有良好的分散性,作为润滑油添加剂,具有良好的抗磨性能.     

壳层可控导电聚吡咯/聚苯乙烯复合微球及聚吡咯中空微胶囊的制备

在导电聚合物含量较小时,含核壳结构的导电聚合物复合粒子就可以具有和本体相当的导电率,且加工性好,近年来这种核壳结构微粒的制备已引起了科学家们的广泛关注．Armes等[制备了导电聚吡咯、导电聚苯胺包覆聚苯乙烯的核壳结构胶体粒子及聚苯胺和二氧化硅的纳米复合物．刘正平等用改进的方法在粒径为116nm的单分散聚苯乙烯乳胶粒子上包覆聚吡咯,     

无皂乳液聚合法制备聚甲基丙烯酸甲酯包覆厚度可控的纳米核-壳二氧化硅微球

用改进的Stöber法和无皂乳液聚合法制备窄分布的二氧化硅/PMMA核-壳纳米微球. 用改进的Stöber法将3-乙氧基甲基丙烯酸丙基硅烷(MPS)修饰在纳米的二氧化硅表面后, 用无皂乳液聚合法制备核-壳纳米微球. 该法简单有效且得到厚度均匀的聚合物包覆层. 随着单体MMA用量的增加, 用动态光散射法测量, PMMA壳层的厚度从6.4 nm增加到96.3 nm. 热重分析表明, PMMA的含量从22.25%增加到93.41%. 扫描电子显微镜和透射电子显微镜结果表明, 得到的是包覆良好、表面光滑的核-壳无机/聚合物纳米微球.     

纳米碳/聚甲基丙烯酸甲酯复合材料的研究

采用脉冲激光轰击浸于流动液相中固体靶的方法,直接连续制备了纳米碳/PMMA的乙酸乙酯溶液,经浇膜法得到了纳米碳/聚甲基丙烯酸甲酯复合材料.光谱分析表明复合体系中存在某种作用,导致该复合材料的玻璃化转变温度明显下降.透射电镜结果表明纳米碳可与聚甲基丙烯酸甲酯形成核/壳结构,使得纳米碳均匀分散于聚合物基体中.热分析结果表明纳米碳的加入对聚甲基丙烯酸甲酯的热分解性能没有显著影响.     

聚甲基丙烯酸纳米水凝胶的水相合成及其磁性功能化

利用十二烷基硫酸钠/吐温20复配表面活性剂和原位生成的聚甲基丙烯酸甲酯(PMMA)种子乳胶,发展了一种可在全水相中"绿色"合成较高浓度的聚甲基丙烯酸(PMAA)纳米水凝胶的新方法.以PMAA纳米水凝胶为前驱体,采用原位氧化沉淀法制备了磁性PMAA纳米微球.利用动态光散射法、FTIR分析、TEM观察、振动样品磁强计测试(VSM)、热重分析(TG)等对纳米水凝胶和磁性微球进行了表征,并探讨了PMAA纳米水凝胶的形成机理.结果表明,吐温20与MAA和PMAA间的氢键作用,促成了交联PMAA/吐温20复合物层在PMMA种子乳胶表面的选择性生长,导致生成了具有核壳结构的PMAA纳米水凝胶.PMAA纳米水凝胶表现出良好的p H响应性,当介质的p H值由1增加至6时,其流体力学体积扩张了近50倍.磁性PMAA纳米微球具有超顺磁性,其饱和磁化强度高达50 A·m~2/kg.     

聚（异丙基甲基丙烯酰胺）@聚（N-异丙基丙烯酰胺）中空微凝胶合成过程的形态学表征

研究了聚（异丙基甲基丙烯酰胺）(PNIPMAM)@聚（N-异丙基丙烯酰胺）(PNIPAM)中空双壳微凝胶的合成过程. 结合扫描电子显微镜、透射电子显微镜的形态学表征方法可简捷直观获得核壳结构微凝胶的粒径尺寸、三维立体及内部超微结构,进而揭示PNIPMAM@PNIPAM中空同心双壳结构微凝胶合成过程的形态学特征.     

铝纳米粒子表面引发聚合制备核壳纳米结构

利用硅烷偶联剂引发法制备核壳结构金属铝纳米粒子(Al NPs)@聚合物, 并研究了聚合反应时间和单体浓度对核壳结构尺寸的影响. 首先合成了硅烷偶联引发剂{2-溴-2-甲基-[3-(三甲氧基硅基)丙基]丙酰胺}, 并通过在甲苯中回流的方法, 将其锚定在金属铝纳米粒子表面. 然后, 在粒子表面引发甲基丙烯酸甲酯的原子转移自由基聚合, 形成聚甲基丙烯酸甲酯(PMMA)壳层. 通过核磁共振波谱仪(NMR)和傅里叶变换红外光谱仪 (FTIR)证明了引发剂和PMMA的成功接枝. 透射电子显微镜(TEM)图像表明, PMMA改性后的金属铝纳米粒子的尺寸和形貌基本不变, 且被厚度约为15 nm聚合物壳层完整均匀地包覆. 此外, 利用动态光散射(DLS)进一步揭示了聚合时间和单体浓度对核壳结构水合直径(D_h)的影响, 发现延长聚合时间或增加单体浓度均可显著提高核壳结构尺寸.     

Preparation of Polypyrrole/Poly(methyl methacrylate) Core-Shell Nanoparticles in Four-Component Microemulsion Media

Electrically conductive polypyrrole (PPy)/poly(methyl methacrylate) (PMMA) core-shell nanoparticles were synthesized by two-step microemulsion polymerization. PPy core particles were prepared in a four-component microemulsion system, which was formed with surfactant cetyltrimethyl ammonium bromide (CTAB), cosurfactant n-pentanol, water, and pyrrole. Ferric chloride and iodine was added as the oxidant and the dopant, respectively. Then the PPy nanoparticles were coated with PMMA to prepare PPy/PMMA core-shell nanoparticles. The morphology of PPy/PMMA core-shell nanoparticles was characterized with transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy was used to characterize the structure of the samples. The electrical conductivities of samples were studied by a Hall effect testing instrument. Despite being coated with a layer of insulation, the conductivity of the composite PPy/PMMA core-shell nanoparticles could still reached to 7.856 × 10^?1 S/cm.     

Preparation of poly(methyl methacrylate)–poly(acrylonitrile‐co‐butadiene) core–shell nanoparticles

Poly(methyl methacrylate)–poly(acrylonitrile‐co‐butadiene) (PMMA–NBR) core–shell structured nanoparticles were prepared using a two‐stage semibatch microemulsion polymerization system with PMMA and NBR as the core and shell, respectively. The Gemini surfactant 12‐3‐12 was used as the emulsifier and found to impose a pronounced influence on the formation of core–shell nanoparticles. The spherical morphology of core–shell nanoparticles was observed. It was found that there exists an optimal MMA addition amount, which can result in the minimized size of PMMA–NBR core–shell nanoparticles. The formation mechanism of the core–shell structure and the interaction between the core and shell domains was illustrated. The PMMA–NBR nanosize latex can be used as the substrate for the following direct latex hydrogenation catalyzed by Wilkinson's catalyst to prepare the PMMA–HNBR (hydrogenated NBR) core–shell nanoparticles. The hydrogenation rate is rapid. In the absence of any organic solvent, the PMMA–HNBR nanoparticles with a size of 30.6 nm were obtained within 3 h using 0.9 wt % Wilkinson's catalyst at 130 °C under 1000 psi of H₂. This study provides a new perspective in the chemical modification of NBR and shows promise in the realization of a “green” process for the commercial hydrogenation of unsaturated elastomers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Poly(methyl methacrylate)/poly(N-isopropylacrylamide) core-shell particles prepared by seeded precipitation polymerization: Unusual morphology and thermo-sensitivity of zeta potential

Poly（methyl methacrylate）/poly（N-isopropylacrylamide） （PMMA/PNIPAM） core-shell particles were synthesized by seeded precipitation polymerization of N-isopropylacrylamide （NIPAM） in the presence of PMMA seed particles. The anionic potassium persulfate was used as initiator, and acrylic acid as functional comonomer. It was shown that the weight ratio of the PNIPAM shell to the PMMA core can be greatly increased through continuous addition of NIPAM monomer at a relatively slow rate. PMMA/PNIPAM particles with different shell thickness were obtained by varying the amount of charged NIPAM monomers. These particles exhibited unique nonspherical core-shell morphology. PMMA core was partially coated by dense hair-like or antler-like PNIPAM shell depending on the shell thickness. The measurement of these particles＇ zeta potential at different temperatures showed that the absolute value of zeta potential unusually decreased as the particle size decreased with temperature.     

Improving thermal and ozone stability of skim natural rubber by diimide reduction

The physical, chemical and thermal properties of diene-based polymers are improved by a chemical modification method such as hydrogenation. Skim natural rubber (SNR) which is mainly comprised of cis-1,4-polyisoprene was hydrogenated by diimide reduction in latex form, using hydrazine and hydrogen peroxide with copper sulfate as catalyst. The effect of various parameters on the level of hydrogenation calculated from proton nuclear magnetic resonance spectroscopy (¹H NMR) was investigated. The kinetic results indicated that the diimide hydrogenation of skim natural rubber latex (SNRL) exhibited a first order behavior with respect to the CC concentration. The apparent activation energy of the catalytic and non-catalytic hydrogenation of SNRL was calculated as 9.5 and 21.1 kJ/mol, respectively. From the TEM micrograph of hydrogenated SNRL particles, non-hydrogenated rubber core and hydrogenated rubber layer were observed according to a layer model. The results from thermal analysis confirmed that thermal stability of hydrogenated SNR was improved compared with the starting SNR. In addition, the thermal aging and ozone resistance of vulcanized hydrogenated SNR blends were also investigated.     

PMMA纳米球的制备及其银膜包覆技术

采用无皂乳液聚合法制备了单分散、直径为170 nm左右的聚甲基丙烯酸甲酯(PMMA)纳米球, 然后利用3-甲基丙烯酰氧基丙基三甲氧基硅烷(MATS)和3-巯丙基三甲氧基硅烷(MPTMS)对PMMA纳米球进行表面改性, 在其表面包覆一层均匀的巯基, 通过巯基与银离子之间的相互作用, 使银在PMMA纳米球表面成核长大, 从而合成PMMA/Ag纳米球壳粒子. 通过扫描电子显微镜、投射电子显微镜和紫外-可见吸收光谱测试技术对产物性能进行了表征, 研究结果表明, 制备的PMMA/Ag纳米球壳粒子的分散性好、包覆均匀.     

Synthesis and characterization of thermo-responsive copolymeric nanoparticles of poly(methyl methacrylate-co-N-vinylcaprolactam)

Copolymeric nanoparticles of methyl methacrylate (MMA) and N-vinylcaprolactam (VCL) were prepared through free radical polymerization using hydrogen peroxide and l-ascorbic acid as a redox initiator in o/w microemulsion containing sodium dodecyl sulphate (SDS). The copolymers were characterized by FTIR and gel permeation chromatography (GPC) and composition of copolymer was determined by ¹H NMR spectroscopy. Reactivity ratio was determined by linear least square and non-linear least square methods. The morphology and particle size distribution of copolymer latexes was determined through transmission electron microscopy (TEM) and dynamic light scattering (DLS). Copolymers were of less than 50 nm size with spherical morphology and latexes were stable for more than 6 months. Phase transition temperature measured through UV-vis spectrometry, for the synthesized copolymer indicates their potential use in biosensors and targeted drug delivery system. Cytotoxicity of nanoparticles was determined by MTT assay on B16F10 melanoma cell lines. Cell viability data shows the IC₅₀ values of copolymeric nanoparticles to be in the range of 0.01-0.1 mg/mL.     

聚甲基丙烯酸甲酯在纳米氧化铝表面的吸附和氢键作用

研究了聚甲基丙烯酸甲酯(PMMA)在纳米氧化铝表面的吸附行为, 采用透射红外光谱研究了吸附的PMMA中的羰基和纳米氧化铝表面羟基之间的氢键作用. 结果表明, PMMA在纳米氧化铝表面的吸附曲线为典型的Langmuir曲线, 饱和吸附值为1.2 mg/m2, 受氢键作用影响, 键合羰基在红外光谱中的吸收峰向低波数方向移动. 根据计算, 羰基的最大键合值(即含键合羰基的甲基丙烯酸甲酯单元的总质量)为0.36 mg/m2, 其余为自由羰基. 随着吸附量的增加, 羰基的键合比例逐渐降低. 吸附达到饱和时, 羰基键合比例为0.30, 说明PMMA主要以平铺的方式覆盖在纳米氧化铝的表面.     

Synthesis of Core-Shell Particles of Polystyrene and Poly(methyl methacrylate) Using Emulsion Photopolymerization

Summary: Submicron core-shell particles of polystyrene (PS) and polystyrene-co-poly(methyl methacrylate) (PS-co-PMMA) coated with PMMA were obtained by emulsion photopolymerization. The seeds of PS or PS-co-PMMA were prepared by emulsion polymerization with or without emulsifier and a ratio of functional monomer and crosslinker (SVBS/EDGMA) in order to obtain different surfaces for the subsequent coating with PMMA. At each stage, the evolution of the average particle size were monitored by using photon correlation spectroscopy (DLS) and the final polymer particles was analyzed via transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The core-shell morphology was identified as the increase of the average particle size in the second stage by DLS technique and by the direct observation by TEM of the differentiation between PS core and PMMA shell, and by the presence of two glass transition temperatures (T_g) as a consequence of the existence of two partially miscible phases.     

完全交替结构乙烯-丙烯共聚物的制备与表征

对顺-1,4含量为100%的高顺式聚异戊二烯(HCPI)进行加氢反应,得到了序列结构高度规整的乙烯-丙烯交替共聚物(alt-EP).所用的HCPI有适当的分子量(Mn=41×104)和极窄的分子量分布(Mw/Mn=1.02).HCPI的加氢反应以环烷酸镍和三异丁基铝为催化剂,在60℃和4.0MPa氢压的条件下反应3h,加氢产物的加氢度为100%.GPC测试结果显示所得乙烯-丙烯交替共聚物保持了窄分布的特点,表明HCPI加氢后未发生交联和降解反应;NMR,FTIR和广角X射线衍射测试结果表明此乙烯-丙烯交替共聚物具有高度规整的序列结构,为完全交替结构的乙烯-丙烯共聚物.并通过TGA和DSC对乙烯-丙烯交替共聚物的热性能进行了表征.