纳米二氧化钛接枝PMMA/PBMA共聚物的表面改性

以羟丙基甲基纤维素(HPMC)对纳米TiO2进行包覆,然后再将纤维素与甲基丙烯酸甲酯/甲基丙烯酸丁酯(MMA/BMA)进行接枝共聚合,对纳米TiO2的进行表面修饰,对复合粒子进行了表征并观察了粒子的形貌.分析表明在纳米TiO2粒子的表面接枝上了MMA/BMA的共聚物;经过处理的纳米粒子的表面均匀地包覆了一层聚合物;改性后的复合纳米粒子TiO2/HPMC-g-PMMA/PBMA的热分解温度比复合物HPMC-g-PMMA/PBMA的热分解温度高56.9 K.     

纳米TiO2-g-PAN复合粒子的合成与表征

采用乙烯基三叔丁基过氧硅烷偶联剂(AC-70)改性纳米二氧化钛(TiO2)粒子,在纳米TiO2粒子表面引入不饱和双键,然后通过溶液聚合在纳米粒子表面接枝聚丙烯腈(PAN),形成TiO2-g-PAN复合纳米粒子,探究了其最佳合成工艺,采用红外光谱和X射线光电子能谱对其进行了表征;并对改性前后的纳米TiO2粒子进行了亲水亲油性测试、接触角测试、扫描电子显微镜分析及紫外线吸收测试。结果表明,PAN成功接枝到纳米TiO2表面;TiO2-g-PAN复合纳米粒子的最佳合成工艺为:反应温度75℃,反应时间5h,纳米粒子和单体之比为1∶6,引发剂用量为1.0%;纳米TiO2经过改性后表面由亲水性变为亲油性,接触角增大,纳米粒子的团聚现象得到明显改善;纳米TiO2-g-PAN粒子具有优良的紫外线吸收性能。     

纳米TiO2表面聚对苯二甲酸乙二醇酯预聚物的改性及表征

利用缩聚聚合,在纳米TiO2颗粒表面接枝聚对苯二甲酸乙二醇酯的预聚物(prePET).通过红外(FT-IR),热失重(TGA)和X射线电子能谱(XPS)分析表明prePET成功接枝在纳米TiO2的表面.透射电子显微镜(TEM)观察表明prePET-TiO2纳米复合粒子粒径大约在30 nm,分散性好.原子力显微镜(AFM)观察表明prePET-TiO2纳米复合粒子在1,1,2,2-四氯乙烷中均匀分散,无团聚.同时发现反应真空度影响了TiO2表面的接枝率,真空度小,接枝率大.扫描电子显微镜(SEM)观察表明prePET-TiO2纳米复合粒子能够在聚碳酸酯(PC)基体中具有良好的分散性,复合粒子填充量的上升增强了prePET-TiO2/PC复合材料的拉伸强度.     

苯乙烯无皂乳液聚合接枝纳米TiO2的研究

采用无皂乳液聚合法，使苯乙烯单体（St）在烷基化预处理的纳米TiO2粒子的表面进行接枝聚合，得到了稳定的以纳米TiO2粒子为核、接枝聚苯乙烯为壳的复合颗粒（TiO2-g-PS）。研究了烷基化预处理以及聚合条件（单体浓度、引发剂浓度、反应时间）对TiO2表面接枝改性的影响，并对其聚合机理进行了探讨。结果表明：PS以化学键成功地接到纳米TiO2的表面，并且可以通过改变接枝聚合的条件来调节粒子上所接聚苯乙烯的结构，为进一步优化纳米粒子填充聚合物复合材料的结构和性能之间的关系建立基础。     

原位聚合法制备纳米TiO2/有机硅改性丙烯酸酯复合乳液

用硅烷偶联剂对纳米二氧化钛(TiO2)粒子表面进行预处理，使其表面由亲水性变为疏水性，并在其表面接枝上可反应的有机官能团。通过改性纳米TiO2表面上的原位聚合反应，制备了纳米TiO2／硅丙复合乳液。透射电子显微镜观察结果显示，乳液中存在两种结构的乳胶粒子：一种是以聚丙烯酸酯为核、有机硅聚合物为壳的核壳结构硅丙乳胶粒子；另一种是以纳米TiO2为核、有机聚合物为壳的纳米TiO2／聚合物复合结构乳胶粒子。乳胶粒子的结构形态可由乳化剂的用量控制。该复合乳液具有较好的杀菌效果，在较短时间内对细菌的杀灭率可达90％以上。     

表面接枝制备PMMA/纳米TiO_2复合粒子的研究

采用表面接枝反应的方法,在纳米TiO2上接枝偶联剂KH-570引入化学键结合的不饱和双键,通过乳液聚合制备了化学接枝的PMMA/纳米TiO2复合粒子。研究了聚合条件对接枝率的变化和微观形态的影响。FT-IR和TGA分析结果表明,TiO2表面偶联剂接枝率为8.86%,聚合物接枝率达62.7%;TEM观察表明,偶联剂处理使纳米TiO2的亲油性提高且粒径没有增加,聚合物接枝后的复合粒子分散性提高。     

通过RAFT聚合制备经GMA偶联的PMMA/TiO2杂化纳米复合物

利用表面修饰法合成了常用单体甲基丙烯酸缩水甘油酯(GMA)修饰的TiO2纳米粒子。以甲基丙烯酸甲酯(MMA)为单体,S-1-十二烷基-S′-(α,α′-二甲基-α″-乙酸)三硫代碳酸酯(DDACT)为RAFT试剂,在纳米TiO2表面进行可逆加成-断裂链转移(RAFT)接枝聚合,PMMA"经表面接枝到(grafting through)"改性后的纳米TiO2表面。结果表明,随聚合时间的增加,纳米TiO2表面接枝聚合物PMMA的量增加,颗粒的团聚得到明显减缓。     

纳米TiO2的表面处理对PET/TiO2复合材料流变特性的影响

采用表面接枝改性的方法对纳米TiO2进行表面修饰,通过熔融共混制得PET/TiO2纳米复合材料,研究了不同表面特性的PET/TiO2复合材料的流变特性。结果表明:加入纳米TiO2的PET体系粘度降低,经表面接枝偶联剂γ-缩水甘油醚氧丙基三甲基硅烷(GPS)或聚甲基丙烯酸甲酯(PMMA)的TiO2对PET粘度的降低程度减弱,当纳米TiO2质量分数大于3%时,粘度趋于稳定。PET/PMMA-TiO2复合体系的粘流活化能最大,温度敏感性强。     

二氧化钛/聚合物复合微球的制备及聚合物表面性质的影响研究

以多孔聚(苯乙烯.二乙烯基苯)接枝马来酸酐聚合微球[P(St-DVB)/MAH]为底物,成功制备了表面均匀包覆纳米二氧化钛(TiO2)的复合微球.主要考察了聚合物微球的表面性质(多孔性和表面功能基团)对TiO2粒子在其表面包覆分散性和数量的影响.复合粒子微球的形态通过扫描电镜和X射线衍射分析等进行了表征.结果表明,聚合物微球的多孔性和表面功能基团都提高了TiO2粒子在微球表面的分散性.平均孔径为136.8 nm的多孔微球与无孔和平均孔径为42 nm的多孔微球相比,能够进一步提高表面TiO2粒子的均匀性和连续性,产生表面均匀覆盖粒径为60 nm TiO2的复合微球.     

壳聚糖改性纳米TiO2的制备及可见光催化性能

采用溶胶-凝胶法制备了壳聚糖(CS)改性纳米TiO2复合粒子。以甲基橙为目标污染物,通过碘钨灯照射进行可见光催化反应研究。考察了合成条件对TiO2/CS纳米复合粒子光催化性能的影响,得出了制备可见光高催化活性TiO2/CS纳米复合粒子的最佳条件:壳聚糖含量1wt%,焙烧温度280℃,焙烧时间2h,pH值为5,凝胶温度25℃。最佳条件下制备的TiO2/CS纳米复合粒子在太阳光下能快速催化降解甲基橙溶液,60min后甲基橙降解率达到99%,表明TiO2/CS纳米复合粒子是一种利用太阳光处理废水的新材料。     

PET/TiO2复合材料非等温结晶行为的研究

采用表面接枝和聚合改性的方法,分别以γ-缩水甘油醚氧丙基三甲基硅烷(GPS)和甲基丙烯酸甲酯(MMA)对纳米二氧化钛(TiO_2)进行表面修饰,通过熔融共混制得聚对苯二甲酸乙二醇酯(PET)/GPS- TiO_2和PET/聚甲基丙烯酸甲酯(PMMA)-TiO_2纳米复合材料,用差示扫描量热法研究了其复合材料的非等温结晶行为,利用不同动力学模型对其结晶过程进行处理。结果表明：未处理的纳米TiO_2提高了PET的熔融温度和结晶温度;而经表面接枝的GPS-TiO_2和PMMA-TiO_2对PET的熔融温度和结晶温度的影响并不显著;不同表面特性的纳米TiO_2降低了PET的结晶度,但经表面接枝后的纳米TiO_2其影响程度减弱;用Jezi- omy法和莫志深法处理PET/TiO_2纳米复合材料的非等温结晶过程比较理想,PET,PET/PMMA-TiO_2,PET/ TiO_2,PET/GPS-TiO_2复合材料的结晶速率依次减小。     

Coating silver nanoparticles on poly(methyl methacrylate) chips and spheres via ultrasound irradiation

Ultrasound irradiation is used for anchoring silver nanoparticles with an average size of ～ 51 nm onto the surface of poly(methyl methacrylate) PMMA chips (2 mm diameter), and silver nanoparticles with an average size of ～ 20 nm onto the surface of the PMMA spheres (1–10 μm). The sonochemical reduction was carried out under argon atmosphere at room temperature. The silver nanoparticles were obtained by the irradiation of a mixture containing the PMMA, silver nitrate, ethylene glycol, ethanol, water, and 24% (wt) aqueous ammonia for 2 h, yielding a PMMA‐nanosilver composite. By controlling the atmosphere and reaction conditions, we could achieve the deposition of silver nanoparticles onto the surface of poly(methyl methacrylate). The silver‐deposited PMMA chips (loaded with 0.01–1.0 weight percent silver) were successfully homogenized in melt by extrusion and then injection molded into small, disc‐shaped samples. These samples were analyzed with respect to their directional spectral optical properties in UV, VIS, and IR spectroscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermal properties of PMMA/TiO2 nanocomposites prepared by in-situ bulk polymerization

The surface of anatase TiO₂ nanoparticles, obtained by the controlled hydrolysis of titanium tetrachloride, was modified by 6-palmitate ascorbic acid. The surface modified TiO₂ nanoparticles were dispersed in methyl methacrylate and mixed with a appropriate amount of poly(methyl methacrylate) to obtain a syrup. The nanocomposite sheets were made by bulk polymerization of the syrup in a glass sandwich cell using 2,2′-azobisisobutyronitrile as initiator. The molar masses and molar mass distributions of synthesized poly(methyl methacrylate) samples were determined by gel permeation chromatography. The content of unreacted double bonds in synthesized samples was determined by ¹H NMR spectroscopy. The influence of TiO₂ nanoparticles on the thermal stability of the poly(methyl methacrylate) matrix was investigated using thermogravimetric analysis and differential scanning calorimetry. The synthesized samples of poly(methyl methacrylate) have different molar mass and polydispersity depending on the content of the surface modified TiO₂ nanoparticles. The values of glass transition temperature of so prepared nanocomposite samples were lower than for pure poly(methyl methacrylate), while the glass transition temperature of samples preheated in inert atmosphere was very similar to the glass transition temperature of pure poly(methyl methacrylate). The thermal stability of nanocomposite samples in nitrogen and air was different from thermal stability of pure poly(methyl methacrylate). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Hydrophobic magnesium hydroxide nanoparticles via oleic acid and poly(methyl methacrylate)-grafting surface modification

Hydrophobic magnesium hydroxide nanoparticles were obtained by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of nanoparticles after oleic acid (OA) modification. The introduction of functional double bonds was firstly conducted on the surface of nanoparticles by OA modification, followed by dispersion polymerization on the particles surface in ethanol solution using methyl methacrylate (MMA) as monomer, azoisobutyronitrile (AIBN) as initiator and polyvinylpyrrolidone (PVP) as stabilizer to graft PMMA on the surface of OA-modified magnesium hydroxide. The obtained composite particles were characterized by XRD, FTIR, TGA, FESEM-EDS, and the compatibility with organic solution was determined by sedimentation test. The results show that the organic macromolecule PMMA could be successfully grafted on the surface of OA-modified magnesium hydroxide nanoparticles, with the dispersibility and the compatibility of nanoparticles greatly improved in organic phase.     

A novel route for the synthesis of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) grafted titania nanoparticles via ATRP

A new method is presented for grafting poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) chains from the surface of TiO₂ nanoparticles via atom transfer radical polymerization (ATRP). First, the ATRP initiators were immobilized onto the TiO₂ surface by using 3-aminopropyltriethoxysilane coupling agent and 2-bromoisobutyryl bromide. Then the copolymerization of 2-hydroxyethyl methacrylate with methyl methacrylate was initiated and propagated on the TiO₂ surface by ATRP. The resulting composite nanoparticles were characterized by means of XPS, FT-IR, ¹H NMR, GPC and TGA. The results indicated that the grafting of copolymer chains from the TiO₂ surface was successful. This method opens up new avenues for the preparation of TiO₂-polymer nanocomposites.     

Synthesis and characterization of nanosilica/polyacrylate composite latex

The nanosilica/polyacrylate organic–inorganic composite latex was synthesized by in‐situ emulsion polymerization of methyl methacrylate (MMA) and butyl acrylate (BA) in the presence of silica nanoparticles, which were modified by silane coupling agent. The surface properties and dispersibility of silica nanoparticles modification, chemical structure, Zeta potential, diameter distribution of the composite latex prepared, surface roughness, and thermal stability of the hybrid film formed by the composite latex were investigated by fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), Zeta meter, ZetaPlus apparatus (dynamic light scattering method), atomic force microscopy (AFM), and thermogravimetric analysis (TGA), respectively. After modification with silane coupling agent, silane was grafted onto the surface of silica nanoparticles to form the organic layers, which was able to efficiently prevent the silica nanoparticles from aggregating to individually homogeneous disperse in the in‐situ emulsion polymerization system and improve the compatibility of silica nanoparticles with the acrylate monomers. The nanosilica/polyacrylate organic–inorganic composite latex prepared had the properties of silica nanoparticles and pure polyacrylate latex but was not simply a combination. Strong chemical bonding tethered the silica and acrylate chains to form the core/shell structural composite latex. Consequently, the hybrid film formed by nanosilica/polyacrylate composite latex exhibited a smooth surface and better thermal properties than the pure polyacrylate film. POLYM. COMPOS. 27:282–288, 2006. © 2006 Society of Plastics Engineers     

Factorial experimental design on synthesis of functional core/shell polymeric nanoparticles via differential microemulsion polymerization

Functionalized core/shell nanoparticles of the co‐polymer of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) could be polymerized by differential microemulsion polymerization, using a small amount of surfactant (the weight ratio of sodium dodecyl sulfate (SDS)/monomer is 1 : 24). The core/shell nanoparticles have a high conversion, high molecular weight, and small particle size (25–30 nm). The statistical analysis indicated that SDS, water, and the interactionbetween SDS and water have a significant positive interaction between the MMA conversion to form the core nanoparticles. For the core‐shell polymer, [GMA], [GMA]*[SDS], and [GMA]* [water] have significant negative effects on conversion; whereas [SDS] and [water], [SDS]*[water] and [GMA]*[SDS]*[water] have positive effects on the conversion to form core/shell nanoparticles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of noncovalent chemical modification on the electrical conductivity and tensile properties of poly(methyl methacrylate)/carbon nanotube composites

Noncovalent chemical modification by initiated chemical vapor deposition technique is applied to carbon nanotubes (CNTs) to reduce average agglomerate size of the nanoparticles in the polymer matrix and to improve surface interaction between the composite constituents. CNT surfaces are coated conformally with thin poly(glycidyl methacrylate) (PGMA) polymer film and coated nanoparticles are incorporated in poly(methyl methacrylate) (PMMA) polymer matrix using solvent casting technique. Conformal PGMA coatings around individual nanotubes were identified by scanning electron microscopy analysis. Transmission electron microscopy and optical microscopy analyses show homogeneous composite morphology for composites prepared by using PGMA coated nanotubes. Fourier Transform Infrared and X‐ray photoelectron spectroscopy analyses show the successful deposition of polymer with high retention of epoxide functionality. PGMA coating of CNTs exhibits improvement in electrical conductivity and tensile properties of PGMA‐CNT/PMMA systems when compared with uncoated nanoparticles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

银纳米颗粒及其负载TiO2的制备与应用研究

采用液相化学还原法和溶胶-凝胶法,制备得到形貌各异的银颗粒及其负载的TiO2复合材料。透射电镜（TEM）结果显示,可以制备得到表面光滑,形状均匀一致的球形、三角形和四方形银纳米颗粒;X射线衍射（XRD）结果表明,银纳米颗粒晶体结构属于立方品系;利用傅立叶变换红外光谱仪（FT—IR）研究了聚乙烯吡咯啉酮（PVP）在生成不同形貌银纳米颗粒的化学反应中的作用机理;Ag／TiO2复合材料的X射线衍射能谱（XPS）结果表明,负载的银主要以零价态形式存在于TiO2的表面;研究了不同形貌银纳米颗粒的抗菌性能以及Ag／TiO2复合材料的光催化脱色亚甲基蓝的活性,结果表明,所制备的银纳米颗粒杀菌率均在99％以上;银负载到TiO2后,Ag／TiO2复合材料的光催化活性得到明显提高。其中,球形银负载的Ag／TiO2复合光催化剂活性最好。     

丙烯酸酯乳液的合成及改性研究

以丙烯酸丁酯(BA)和丙烯酸-2-乙基己酯(2-EHA)为软单体、甲基丙烯酸甲酯(MMA)为硬单体、丙烯酸(AA)为功能单体、甲基丙烯酸羟乙酯(HEMA)为交联单体和十二烷基硫酸钠(SDS)/乳化剂(OP-10)为阴/非离子型复合乳化剂,采用核/壳种子乳液聚合法制备了丙烯酸酯共聚乳液;然后在壳层聚合时寸加入HEMA,并用乙烯基有机硅进行改性,制得硅丙乳液。结果表明:当m(SDS):m(OP-10)=3:2、w(复合乳化剂)=3.4%、w(引发剂)=0.82%、w(HEMA)=3.5%、聚合温度为80℃以及聚合中期加入6.8%乙烯基硅油至壳单体中时,硅丙乳液及其胶膜的稳定性、耐水性和力学性能俱佳。