Preparation of Self-crosslinked Fluorocarbon Polymer Emulsion with Core-shell Structure by the Method of Soap-free Emulsion Polymerization

Using methyl methacrylate （MMA）, butyl acrylate（BA） and hexafluorobutyl acrylate（HFBA） as main raw materials, we prepared self-crosslinked fluorocarbon polymer emulsion with core-shell structure via soap-free emulsion polymerization when the conception of particle design and polymer morphology was adopted. Moreover, the influence of mole ratio of BA to MAA, pH value on the oligomer was studied. And the effects of the added amount of oligomer, self-crosslinked monomer and HFBA, mass ratio of BA to MMA, reaction temperature and the initiator on the polymerization technology and the performance of the product, were investigated and optimized. The structure and performance of the fluorocarbon polymer emulsion were characterized and tested with FTIR, TEM, MFT and contact angle and water absorption of the latex film. The experimental results show that the optimal conditions for preparing fluorocarbon polymer emulsion are as follows： for preparing the oligomer, tool ratio of BA to MAA is equal to 1.0 ： 1.60, and pH value is controlled within the range of 8.0 and 9.0; for preparing fluorocarbon polymer emulsion, the added amount of oligmer[P（BA/MANa）] is 6%; mass ratio of BA to MMA is 40 ＂ 60; the added amount of self-crosslinked monomer is 2%, the added amount of HFBA is 15 %; reaction temperature is 80 ℃; the mixture of potassium persulfate and sodium bisulfite is used as the initiator. The film-forming stability of the fluorocarbon polymer emul- sion and the performance of the latex film, which is prepared with the soap-free emulsion polymerization, are better than that prepared with the conventional emulsion polymerization.

NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)microspheres were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as stabilizer.The surfaces of PDVB microspheres werechloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzeneinitiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system.Polystyrene was found to begrafted not only from the particle surfaces but also from within a thin shell layer,resulting in the formation of particles sizeincreased from 2.38-2.58 μm,which can further grow to 2.93 μm during secondary grafting polymerization of styrene.Thisdemonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature.All of the preparedmicrospheres have narrow particle size distribution with coefficient of variation around 10%.

Two-Photon Fluorescence Properties and Ultrafast Responses of a Hyperbranched Diketo-Pyrrolo-Pyrrole Polymer with Triphenylamine as the Core

The two-photon fluorescence properties and ultrafast responses of a hyperbranched polyyne （hb-DPP-J2） with triphenylamine as the central core, Diketo-Pyrrolo-Pyrrole as the connecting unit and electron acceptor are studied. The polymer has a D-π-A-π-D conjugated structure along the extended polyyne w-bridge systems, and the effective condugated unit repeats itself in the whole hyperbranehed polymer chain. The polymer exhibits a large two-photon absorption cross section and high fluorescence quantum yields. The ultrafast dynamic results give a deep understanding of the excited energy transfer processes under excitation, and reveal a long relaxation lifetime of the intramolecular charge transfer （ICT） state.

MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

Grafting of poly(methyl methacrylate)from narrow disperse polymer particles by surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)particles were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as the stabilizer.Chloromethylated PDVB was used as initiating coresites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system.It was found that poly(methylmethacrylate)was grafted not only from the particle surfaces but also from within a thin shell layer,leading to particles sizeincreases from 2.38-3.00 μm with a core-shell structure particles.The grafted core-shell particles were characterized withFTIR,SEM,DSC.

磁性核壳微球的制备及其性能

以苯乙烯、甲基丙烯酸为单体,在偶氮二异丁腈引发下通过分散聚合合成了羧基化纳米单分散共聚微球。用化学沉淀法在共聚微球表面生成均匀分散的纳米四氧化三铁壳层,采用FTIR、SEM、DLS、HR-TEM、XRD、XPS及VSM对微球进行形貌及结构表征。结果显示微球均有良好单分散性且在水相中分散性良好。以BSA为模型研究了核壳微球蛋白分离性能,在体系pH值为4.7时微球对蛋白分离效果最佳,吸附等温线符合Langmuir等温吸附模型,微球的蛋白分离性能达到239.5 mg/g。

不同引发体系合成有机硅-聚苯乙烯核壳结构微球的研究

以羟基硅油、苯乙烯为主要原料,采用半连续乳液聚合方法制得具有核壳结构的有机硅-聚苯乙烯聚合物乳液,将其进行喷雾干燥制得聚合物粉末,考察了3种不同引发体系对聚合物乳液稳定性和单体转化率的影响,并对其进行了红外光谱、透射电子显微镜分析。结果表明,3种引发体系均成功合成了有机硅-聚苯乙烯共聚物,且制得的聚合物乳液有较明显的核壳结构和较好的稳定性;采用过硫酸铵、亚硫酸氢钠和过氧化二苯甲酰组成的复合引发体系(APS+NaHSO3+BPO)制备的聚合物乳液单体转化率最高,可达93.24%。对由APS+NaHSO3+BPO复合引发体系制备的聚合物粉末进行了扫描电镜和热失重表征,结果显示,在-50~180℃内有机硅-聚苯乙烯粉末没有明显的失重峰,在500~580℃区间内,粉末热失重达61.91%,表明该聚合物具有良好的耐高低温性能,可在较宽温度范围内使用并仍旧保持良好的性能。

《高分子材料成型模具》教学案例讨论

从两个教学案例出发,分别讨论了斜导柱滑块抽芯机构中滑块抽拔距和抽拔方向与开模方向之间倾角之间的关系,加深了对于模具工作原理的理解,及模具冷却水道设计中塑件壁厚、水道直径等因素与导热效果之间的关系。前一个教学案例有利于培养学生批判性思维,后一个案例将计算机编程与模具设计结合,系统地对比分析了各个因素对应的结果,减轻了繁杂的运算过程,提高了设计效率,培养了学生解决复杂工程问题的能力。

Preparation of Core-shell Structured Particles and Their Nucleation in Polyester:I. Preparation of Monodisperse SiO_2/PS Core-shell Composite Particles

To enhance the nucleation and crystallization properties of polyester (e.g., polyethylene terephthalate, PET), core-shell structured particles are used to improve these properties by controlling the inorganic dispersion properties in the polymers. In the paper, monodisperse particles of silica/polystyrene (PS) are prepared with both dispersion and emulsion polymerization techniques. The monodisperse silicon dioxide particles are first prepared with the seed growth method and modified by the coupling agents. Silica is properly modified with KH-570, and its size deviation is 3.0% or so. The modified silica then reacts with the mixture of ethanol, water medium, and monomer of styrene under dispersion polymerization. Results show that the dispersion polymerization technique is more suitable for monodisperse core-shell SiO2/PS particles than that of the emulsion. The morphology and molecular structure of the core-shell particles are investigated with the transmission electron microscope (TEM), and fourier transform infra-red spectroscopy (FTIR). The results show that the modified silica particles are successfully encapsulated with polystyrene. The average number of silica particles encapsulated into each polystyrene sphere decreases when the size of silica particles increases from 50 nm to 600 nm, and will approach one when the silica is greater than 380nm in size. The mass ratio for silica/PS particles in emulsion polymerization is 4.7/1, lower than that of 6.8/1 for dispersion polymerization, which is the first reported optimized data for preparing the similar monodisperse composite particles. Thus, the PS shell in the former is thinner than that in the latter.

THE PREPARATION AND CHARACTERIZATION OF SBR/PS CORE-SHELL PARTICLES BY GAMMA IRRADIATION

A kind of core(SBR)-shell(PS)particles was synthesized by using SBR latex and grafting with St under gammairradiation.The influences of absorbed dose and dose rate on the grafting yield of PS on SBR seed latex have beeninvestigated.Results show there was a transition layer which contained the SBR/PS graft copolymer between the SBR coreand PS shell.Dynamic laser scattering(DLS)and differential scanning calorimetry(DSC)results confirm the existence ofgrafted polystyrene,and transmission electron microscope(TEM)observation verifies the core-shell structure of SBR-g-PSlatex.Such SBR/PS core-shell latex could be processed easily to ultrafine rubber powders by using spray drying andexpected to be used as an impact modifier for PS.

聚合物微球制备与复合体系封堵性能研究

为探究基于聚合物微球的复合调剖体系在高渗岩心中的运移、封堵能力,以沉淀聚合法合成了聚甲基丙烯酸甲酯微球,采用ic-Ramam、FT-IR、SEM等手段剖析了微球的结构组成与成球机理,并以人造岩心评价了微球与复合体系的封堵性能。结果表明:聚合物微球成球均匀、形貌规整,粒径约为300 nm,呈单分散分布,与非乳化自稳定条件下均相成核相关;微球抗冲刷封堵性能好,对400mD岩心封堵率>80%,复配乙烯基增黏聚合物可进一步提高体系黏滞、封堵性能,复合体系封堵率高达98.91%。

新型水性丙烯酸核壳分散体合成工艺影响因素研究

通过新型溶液聚合方法制备了具有核壳结构的水性丙烯酸分散体,对其聚合工艺影响因素进行了研究,利用红外光谱仪、激光粒度仪对合成的水性丙烯酸核壳分散体进行了表征分析。研究结果表明:最佳的聚合工艺为聚合温度范围为130~133℃、核壳单体滴加时间为2.5h/1.5h、核壳单体滴加完毕保温时间为1h/1h。在该聚合工艺下合成的水性丙烯酸核壳分散体黏度适中,粒径较小且分布较窄,平均粒径为156.8 nm。红外表征结果表明单体已经基本聚合完全。制备的涂膜具有较高的光泽、优良的干性以及优异的机械性能等特性。

聚(1-乙烯基-2-吡咯烷酮)包覆明胶纳米颗粒的制备及其抗生物淤积性能研究

通过两步脱溶剂法制备得到了具有均匀尺寸分布的明胶纳米颗粒(GNPs)。以GNPs为模板利用原位自由基聚合方法在其表面包覆聚(1-乙烯基-2-吡咯烷酮)(PVP)的交联聚合物外壳,得到了具有明确核-壳结构的复合纳米颗粒GNPs@PVP。通过动态光散射(DLS)、透射电子显微镜(TEM)、傅立叶变换红外光谱(FTIR)等对该体系的尺寸分布、表面电荷、微观形貌和结构等进行了表征,并通过小鼠血清蛋白吸附实验评价了体系的抗生物淤积效果。结果表明,相比于包覆前的明胶纳米颗粒,GNPs@PVP的粒径有了明显增加,而表面电荷则由负电性转变为趋近于电中性。在m(GNPs)∶m(NVP)=1∶10的条件下,纳米微粒成膜后的非特异性蛋白质吸附率从21.1%±1.7%降低至1.2%±0.2%,表现出了良好的抗生物淤积效果。

聚苯乙烯/纳米TiO_2复合粒子的制备

用硅烷偶联剂WD 70改性纳米TiO2粒子,应用超声技术将纳米TiO2粒子分散在异丙醇介质中,然后进行苯乙烯的分散聚合包覆,成功地制备了以聚苯乙烯为壳、纳米TiO2粒子为核的有机/无机复合粒子.观察复合粒子的形貌发现纳米TiO2粒子完全包覆在聚苯乙烯微球中.通过红外、X射线光电子能谱等表征手段,还发现聚苯乙烯链是通过偶联剂WD 70以化学键的方式与纳米TiO2粒子相连.

核壳聚合与核壳结构聚合物乳液

对核 /壳乳液聚合机理、方法、工艺以及核 /壳结构聚合物乳液的制备和性能进行了综述 ,重点讨论了各种因素对核 /壳结构聚合物乳胶粒子形态的影响 ,并回顾了核 /壳乳液聚合最新的研究动态。

聚硅氧烷/丙烯酸酯核/壳复合胶乳的粒径分布与成核机理

通过种子乳液法合成出具有高有机硅含量核 壳结构的聚硅氧烷 丙烯酸酯复合粒子 .研究了聚合方法、乳化剂浓度、引发剂浓度、单体滴加速度等工艺条件对复合乳液粒径尺寸、分布与形态的影响 ,并对复合乳液的成核机理进行了探讨 .研究表明 ,乳化剂浓度对乳液粒子的粒径分布和形态、结构有显著影响 ,引发剂浓度增加将使粒子粒径减小 ;相对一次投料法 ,种子乳液法生成的粒子分布窄 ,具有明显核壳结构 ,通过壳层单体滴加速度可以控制粒子的粒径尺寸和分布 ;而壳层丙烯酸酯聚合物主要是在聚硅氧烷种子表面的“过渡层”聚合、富集而成 .

表面含羧基磁性高分子复合微球的制备

用化学共沉淀法制备了F e3O4纳米微粒,并对F e3O4微球表面进行改性,以磁性F e3O4为核,通过苯乙烯和丙烯酸的乳液共聚,制备了粒径均匀、以苯乙烯和丙烯酸共聚物为壳、表面含有一定羧基的磁性高分子纳米复合微球。测定了此微球的形态、结构和粒径,探讨了聚合单体、乳化剂等因素对微球合成的影响。

核壳型交联丙烯酸酯共聚物的合成及表征

采用种子乳液共聚方法合成了以BA、2-EHA为核层共聚单体,St、MMA为壳层共聚单体,1,4-丁二醇二丙烯酸酯为核壳层交联剂的共聚物(ACR)。借助动态光散射粒径分析仪、DSC、TEM分别考察了乳胶粒的粒径及其分布、共聚物玻璃化转变温度以及乳胶粒的微观形态结构。实验结果表明,共聚物具有明显的三个玻璃化转变温度(Tg),分别对应ACR的核层、接枝过渡层、壳层的Tg,且ACR乳胶粒呈现规整的核壳结构。当壳层苯乙烯含量大于70%时,所合成的乳胶粒结构表现明显的异常核壳形态(夹心形)。

聚硅氧烷/甲基丙烯酸甲酯核壳结构复合粒子的制备

由种子乳液聚合法合成了具有高硅含量 (m(有机硅 )∶m(丙烯酸酯 ) =7∶6)的核 /壳结构聚硅氧烷 /甲基丙烯酸甲酯的复合粒子。研究了乳化剂类型与浓度、反应温度、引发剂浓度和聚合方法等工艺条件对聚合动力学、复合粒子的粒径分布及形貌的影响。结果表明 ,采用m(SDS)∶m(OP 1 0 ) =1∶1的复合乳化剂可以获得粒径小 ( 1 0 0nm)、分布窄的稳定复合乳液 ;随着乳化剂浓度的增加 ,乳液粒子粒径变小、单体转化率增加 ;提高催化剂、引发剂浓度将会提高单体转化率 ;相对一次投料法 ,由甲基丙烯酸甲酯单体滴加的种子乳液聚合法合成的复合粒子粒径均一、形态规整、具有明显的核 /壳结构。