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%.

SYNTHESIS OF CdS/SiO_2/POLYMER TRI-LAYER FLUORESCENT NANOSPHERES WITH FUNCTIONAL POLYMER SHELLS

Tri-layer CdS/SiOz/polymer hybrid nanospheres were synthesized by distillation precipitation polymerization of either ethyleneglycol dimethacrylate （EGDMA） or EGDMA together with comortomers havirLg different functional groups, such as methacrylic acid, 4-vinylpyridine and 2-hydroxyethylmethacrylate, in the presence of 3-（methacryloxy）propyl trimethoxysilane （MPS）-modified CdS/SiO2 nanoparticles as seeds in acetonitrile with 2,2＇-azobisisobutyronitrile （AIBN） as initiator. In this approach, MPS-modified inorganic seeds were prepared by the modification of CdS/SiO2 nanoparticles via the self-condensation reaction between the hydroxyl groups of sinaols, in which the CdS/SiO2 nanoparticles were afforded by a reverse microemulsion technique for the synthesis of CdS core nanoparticles with the subsequent coating of silica layer. The polymer shell-layers encapsulated over the MPS-modified CdS/SiO2 inorganic seeds via the efficient capture of the monomers and oligomers from the solution with the aid of the vinyl groups incorporated by the MPS modification, in which the polymer shell-thickness and functional groups including carboxyl, pyridyl and hydroxyl, were facilely controlled by the feed of EGDMA as well as the types of comonomers used for the polymerization. These nanospheres were characterized by transmission electron microscopy （TEM）, Fourier-transform infrared spectroscopy （FT-IR）, thermogravimetric analysis （TGA）, fluorescence spectroscopy and zeta potential.

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.

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.

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.

聚苯乙烯/聚吡咯Yolk-Shell结构微粒的制备

Yolk-Shell中空微球由于其独特的结构,在催化剂、电池、生物医药等领域具有潜在应用,引起了高分子材料微球领域专家的研究兴趣。采用界面化学氧化聚合法制备了具有Yolk-Shell结构的聚苯乙烯/聚吡咯微粒。首先以惰性溶剂对二甲苯(PX)溶胀聚苯乙烯种子微球,然后通过界面化学氧化聚合在其表面包覆一层聚吡咯,形成具有核壳结构的复合微粒。随着PX的挥发,微粒的内核与外壳逐渐产生分离,从而在其内部形成连续的空腔。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、热重分析仪(TGA)、傅里叶红外光谱(FT-IR)等对微粒的形貌、热性能及结构组成进行了表征分析,探究了吡咯聚合条件、吡咯用量、PX用量以及种子微球粒径等因素对微粒形貌的影响。结果表明,室温条件下进行吡咯的聚合可制备出Yolk-Shell中空微球;随着吡咯用量的减少,微粒的分散性明显改善;随着PX用量的增加,复合微粒空腔变大;相对于CPS微球,以非交联PS微球为种子制备得到的复合微粒空腔更大,且粒径越大,空腔结构越明显。

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。

甲鱼蛋白源寡肽体外对微管蛋白聚合-解聚调控模式的影响

为探讨甲鱼蛋白源寡肽对肿瘤细胞微管蛋白活性的调控机制,本研究以前期获得的甲鱼蛋白源三条寡肽DEADLLA(D-7-A)、EAGVNDW(E-7-W)、GSISSGQV(G-8-V)为研究对象,评价其对微管蛋白聚合-解聚的影响,解析其与微管蛋白的作用模式,阐释其诱导肿瘤细胞凋亡作用的机制。结果表明,3条寡肽与长春新碱相似,均为微管蛋白聚合的抑制剂,IC_(50)值分别为3.72、5.01、5.95μmol/L。分子对接结果显示,D-7-A与α-微管蛋白4X1I活性中心结合位点为Ser178和Thr179;E-7-W与活性中心结合位点为Gln15、Thr225、Tyr224、Tyr210、Arg214;G-8-V与活性中心结合位点为Gln11、Ser178、Asp329,与α-微管蛋白具有较强的作用力。细胞实验结果表明,D-7-A、E-7-W、G-8-V均对A549细胞具有抑制作用,且具有剂量依赖性,其IC_(50)值分别为2003±72、1877±102和1789±137μmol/L。G-8-V对A549细胞的抑制效果最强,且具有诱导A549细胞凋亡的作用,并随着药物处理时间的增加,凋亡率明显提高,其作用机制是通过影响α-微管蛋白的价键,抑制微管蛋白的聚合,诱导细胞凋亡。

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。

界面聚合法制备微胶囊相变材料的试验研究

以相变石蜡为芯材,廉价的聚脲和聚氨酯为壁材,采用界面聚合法制备了单层和双层壁材微胶囊相变材料,并用差示扫描量热仪(DSC)和TG分析仪分别对所制备的单层壁材微胶囊和双层壁材微胶囊进行了测试。结果表明,与同条件下制备的单层壁材微胶囊相比,双层壁材微胶囊在合成过程中反应充分、产率较高,在室温环境下相变温度为19.02℃,且保持了较高的相变潜热(79.9J/g),适合于建筑用相变材料。

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.

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。

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。

共聚物酸掺杂接枝聚苯胺的研究

采用核壳乳液聚合方法合成了以甲基丙烯酸甲酯、甲基丙烯酸和丙烯酸丁酯三元共聚物酸为核 ,聚苯胺为壳的导电高分子复合物。复合物的电导率随着聚苯胺含量的增加而升高。用粒径分析仪、TEM、FT -IR和DSC对复合材料进行了表征。结果表明形成了核壳结构 ,由于共聚物酸起到了掺杂剂的作用 ,使制得的复合物能在环己酮、四氢呋喃等普通有机溶剂中有好的溶解性。

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)。