PMMA/nano-SiO2纳米复合材料的制备和表征

PMMA/nano-SiO2纳米复合材料的制备和表征;二氧化硅;聚甲基丙烯酸甲酯;溶液聚合     

氧化石墨烯/PMMA和表面官能化的石墨烯/PMMA复合材料的制备及其力学性能的研究

使用简单的溶液共混的方法制备了氧化石墨烯/聚甲基丙烯酸甲酯(GO/PMMA)和表面官能化的石墨烯/聚甲基丙烯酸甲酯复合材料.通过透射电镜(TEM),扫描电镜(SEM)和原子力显微镜(AFM)观察了石墨烯及复合材料的表观形貌.通过拉伸实验表征了其力学性能,研究发现随着石墨烯的加入,其拉伸强度和断裂伸长率都有所改善,而且表面官能化的石墨烯的复合材料的改善效果要优于氧化石墨烯.     

层离型PMMA/镁铁双氢氧化物纳米复合材料的热降解研究

通过原位聚合方法制备了以非水溶性聚合物(聚甲基丙烯酸甲酯,PMMA)为基体,与MgFe双氢氧化物(LDH)具有良好相容性的层离型纳米复合材料.采用小角、广角X射线衍射(XRD)及透射电镜(TEM)对纳米复合材料的微观结构进行了分析,通过热重分析(TG)和玻璃化转变研究了纳米复合材料在空气和氮气氛围下的热降解过程.实验结果表明,MgFe-LDH的引入显著提高了聚合物基体的热降解温度和玻璃化转变温度,纳米复合材料的热稳定性显著提高.其中含量1.6 wt%的层离型纳米复合材料在失重50%时的热降解温度比纯样提高约69℃.并且整个纳米复合体系的相容性良好,含量8.0 wt%的样品,其可见光透过率仍可达90%以上.     

SiO2交联剂交联MMA聚合制备PMMA/SiO2纳米复合材料

用SiO2交联剂(SiO2HPA)交联甲基丙烯酸甲酯(MMA)自由基聚合制备PMMA SiO2纳米复合材料。采用两步法将可聚合乙烯基单体以化学键的形式键接到SiO2表面合成SiO2交联剂,首先利用过量的甲苯2,4二异氰酸酯(TDI)对SiO2纳米粒子表面进行化学修饰合成出表面带有高反应活性NCO基团的功能化SiO2粒子(SiO2TDI),SiO2TDI与丙烯酸羟丙酯(HPA)反应合成SiO2交联剂。系统研究了MMA单体与SiO2交联剂投料比及聚合时间对聚合反应的影响。此外,利用红外光谱(FT IR)、DSC、TGA、可见光光谱仪等实验手段对纳米复合材料进行了表征分析。结果表明,纳米SiO2粒子在复合材料中起着物理交联点和化学交联点作用,复合材料玻璃化转变温度(Tg)明显地高于其纯PMMA的玻璃化转变温度,随着纳米SiO2粒子含量的增加,复合材料玻璃化温度升高,而透明度明显降低。     

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.     

纳米SiO_2/聚甲基丙烯酸甲酯复合材料的制备和力学性能

通过悬浮聚合的方法,用不同表面结构的纳米SiO2对聚甲基丙烯酸甲酯(PMMA)进行原位改性,得到纳米SiO2/聚甲基丙烯酸甲酯复合材料;利用红外光谱仪分析了复合材料的界面化学结构,利用热分析仪测定了其热稳定性,并采用冲击试验机测定了其力学性能.结果表明,不同表面结构的纳米SiO2均参与甲基丙烯酸甲酯的聚合反应,与PMMA基体之间形成化学键;而表面修饰有双键的纳米SiO2更易与甲基丙烯酸甲酯聚合,能更有效地提高PMMA的抗冲击性能.     

纳米层状双金属氢氧化物改性PU/PMMA的制备及其弛豫行为

采用原位聚合法,制备了聚氨酯(PU)/聚甲基丙烯酸甲酯(PMMA)/层状双金属氢氧化物(LDH)纳米复合体系(PU/PMMA/LDH).通过广角X射线衍射(WXRD)、透射电子显微镜(TEM)对其结构和形貌进行了表征,并通过热失重(TGA)、动态力学分析(DMA)和宽频介电谱(BDRS)研究了LDH含量(φ)对PU/PMMA体系热稳定性和弛豫行为的影响.结果表明,当φ<1 wt%时,LDH在聚合物基体中以剥离结构为主,PU/PMMA/LDH体系的玻璃化温度(Tg)降低,最大损耗因子(tanδmax)增大;而当φ>1 wt%时,LDH在聚合物基体中以插层结构为主,插层结构对聚合物分子链的限制使复合体系的Tg升高、tanδmax降低.LDH表面与PU硬段间的氢键作用,使复合体系的α介电弛豫转变随φ增加而向高温方向移动,弛豫过程激活参数增大.     

PMMA/PS纳米复合材料的制备及分散相稳定性研究

纳米复合材料具有许多优异的性能,但是由于纳米粒子常常很难以纳米尺寸均匀地分散在基体中,有时即使实现了纳米级分散,在后加工或应用过程中又会发生二次团聚,使得纳米材料的特性不能充分发挥．因此,要获得性能优异的纳米复合材料首先必须解决纳米材料在基体中的均匀、稳定分散问题．     

PMMA/黑云母纳米复合材料的制备及表征

采用乳液聚合法制备了聚甲基丙烯酸甲酯 黑云母 (PMMA VMT)纳米复合材料 ,其中的黑云母经甲基丙烯酰氧乙基三甲基氯化铵有机改性 ,所得复合材料经XRD、FT IR、DSC、TG等测试结果证明云母已经被有效的剥离 ,复合材料的耐热性能、玻璃化转变温度 (Tg)比PMMA都有所提高 ,但聚合反应速率有所下降 ,复合材料中可萃取的聚合物粘均分子量升高 .     

反胶束模板制备聚甲基丙烯酸甲酯/无机纳米粒子/石墨纳米复合材料及其表征

以甲基丙烯酸甲酯(MMA)和三氯甲烷(CHCl₃)为油相制备反胶束微乳液, 依靠表面活性剂十六烷基三甲基溴化铵(CTAB)自组装形成的“微反应器”作为模板成功地制备了PMMA/Eu(OH)₃/EG和PMMA/Ni(OH)₂/EG纳米复合材料. 并用红外光谱(IR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和差热-热重(TG-DTA)对该复合材料进行了表征和分析. 研究结果表明, 反胶束法可以有效地应用于有机-无机纳米复合材料的制备.     

Structure Characterization and Thermal Properties of PMMA／Montmorillonite Nanocomposites via Emulsion Polymerization

Montmorillonite(MMT) modified with sodium silicate can change the arrangement of its layers fromedge-face and edge-edge to face-face. With the fine dispersion of the modified MMT in water, the cation-ex-change reaction was carried out with cetyltrimethyl ammonium bromide (CTAB) to obtain organo-montmoril-lonite (OMMT). As OMMT was uniformly dispersed in methyl methacrylate (MMA) monomer, PMMA/OMMT nanocomposites were formed via a common emulsion polymerization. The products were extractedwith hot acetone and characterized by FTIR, molecular weight, X-ray diffraction(XRD), transmission elec-tron microscopy(TEM), DSC and TGA. These results show that most of the OMMT layers have been exfo-liated, while the thermal stability is increased obviously. By means of FTIR spectral analysis, the ratios ofthe macromolecular radicals‘ termination of disproportionation patterns to combination are increased with theaddition of OMMT. This result further confirms the increase of the thermal degradation temperatures andglass transition temperatures of the PMMA/OMMT nanocomposites.     

Synthesis and characterization of poly（methyl methacrylate-co-polyhedral oligomeric silsesquioxane） hybrid nanocomposites

A novel poly(methyl methacrylate-co-polyhedral oligomeric silsesquioxane) hybrid nanocomposite was synthesized by free radical polymerization and characterized by ~1H NMR,~(29)Si NMR,and TGA technologies.Compared with PMMA homopolymer, the nanocomposite has better thermal stability.     

CdS/SiO2纳米复合材料的合成及光学性能

以合成的丙氨酸镉为纳米粒子的前驱体,在不加酸或碱性催化剂的条件下,利用丙氨酸镉分子中的胺基催化硅氧烷水解缩合生成二氧化硅,同时将丙氨酸镉均匀地引入到二氧化硅的内部,通过硫化原位生成硫化镉纳米颗粒,制得硫化镉/二氧化硅(CdS/SiO2)纳米复合材料.用傅里叶变换红外光谱、核磁共振氢谱、紫外-可见光谱、荧光显微镜和透射电子显微镜等方法对CdS/SiO2复合材料进行表征,结果表明,硫化镉粒子均匀分布在二氧化硅内部,使其具有良好的荧光特性.     

PS-PMMA嵌段共聚物/PMMA在选择性溶剂中的自组装行为

用动态光散射和透射电镜研究了嵌段共聚物聚苯乙烯-聚甲基丙烯酸甲酯(PS-b-PMMA)和其对应的均聚物聚甲基丙烯酸甲酯(PMMA)在选择性溶剂四氢呋喃/环己烷(THF/CYH)中的自组装行为.选择性溶剂对PS嵌段是良溶剂,对PMMA嵌段和均聚物PMMA是非良溶剂,实验结果表明,在适当的分子量及组成条件下,PS-PMMA/PMMA在选择性溶剂中形成了单分散的纳米胶束,均聚物PMMA与PMMA嵌段一同形成了胶束的核,通过控制均聚物PMMA的量可以在较大的范围内调整胶束的尺寸.     

Preparation and characterization of microporous PVDF/PMMA composite membranes by phase inversion in water/DMSO solutions

PMMA/PVDF composite membranes were prepared by isothermal immersion-precipitation of dope solutions consisting of PMMA, PVDF, and DMSO into both harsh and soft nonsolvent baths. The effects of PMMA and DMSO contents on the membrane morphology, crystal structure, thermal behavior and tensile strength of the formed membrane were investigated. For a PMMA-free casting dope immersed in a harsh bath, such as pure water, the formed membrane exhibited a typical asymmetric morphology characterized by skin, finger-like macrovoids, and cellular pores. In contrast, when a soft 70% DMSO bath was adopted, PVDF crystallized to form a membrane packed by spherulitic globules. Incorporation of PMMA gave rise to interesting morphological features; e.g., PVDF globules were observed to adhere to the interlocked polymer branches coexisting with the continuous porous channels, as revealed by high resolution FESEM imaging. XPS analysis of the surfaces of the composite membranes suggested the occurrence of a surface segregation phenomenon, wherein PVDF preferentially migrated to the top surface region of the membrane such as to minimize the interfacial energy. XRD analyses indicated that PVDF crystallized into ‘α’ structure in both PVDF and PMMA/PVDF composite membranes. The crystallinity of the membranes was found to decrease with increasing PMMA content, which was confirmed by DSC thermal analyses. The latter results also indicated a significant decrease in membrane’s melting temperature as the PMMA content was increased. Tensile strengths of the membranes were improved by inclusion of PMMA in either harsh or soft baths. However, elongation at break showed a reversed trend.     

Synthesis and electrorheological response of nano-sized laponite stabilized poly(methyl methacrylate) spheres

Poly(methyl methacrylate) (PMMA) nanospheres were fabricated via surfactant-free Pickering emulsion polymerization, in which hydrophilic laponite clay was used to stabilize the emulsions of methyl methacrylate dispersed in distilled water. These synthesized PMMA nanoparticles, of which the surface is compactly wrapped by laponite clay, are observed, as confirmed by scanning electron microscopy and transmission electron microscope images. Fourier-transform infrared spectra and thermogravimetry analysis confirm the chemical composition, thermal property, and mass percent of the laponite located on the surface of PMMA particles. Finally, laponite-wrapped nano-sized PMMA spheres were adopted as an electrorheological material. By using an optical microscope, the chain-like structure was observed when an external electric field was applied. In addition, the ER performance was also examined via a rotational rheometer equipped with a high voltage generator.     

纳米CeO_2/PMMA杂化材料的制备与表征

采用在位分散聚合法制备了纳米CeO2 /PMMA杂化材料.XRD分析表明,杂化材料是无定形的.SEM分析表明,杂化材料中CeO2 含量不同,材料的断面形貌明显不同,随CeO2 含量的增加,杂化材料由韧性断裂向脆性断裂转变.EDS面分析表明,Ce在杂化材料中分布均匀.实验表明,随CeO2 含量的增加,杂化材料的透过率和溶解性降低     

The role of the trivalent metal in an LDH: Synthesis, characterization and fire properties of thermally stable PMMA/LDH systems

Two layered double hydroxides (LDHs), calcium aluminum undecenoate (Ca₃Al) and calcium iron undecenoate (Ca₃Fe), have been prepared by the co-precipitation method. XRD analysis of these LDHs reveals that they are layered materials and FT-IR and TGA confirmed the presence of the undecenoate anions in the material produced. The PMMA composites were prepared by bulk polymerization and the samples were characterized by XRD, TEM, TGA and cone calorimetry. Both additives greatly enhance the thermal stability of PMMA, while the calcium aluminum LDH gives better results when the fire properties were examined using the cone calorimeter.     

Synthesis of nano-ZnO/poly(methyl methacrylate) composite microsphere through emulsion polymerization and its UV-shielding property

Nano-ZnO/poly(methyl methacrylate)(PMMA) composite latex microspheres were synthesized by in-site emulsion polymerization. The interfacial compatibility between nano-ZnO particles and PMMA were improved by treating the surface of nano-ZnO particles hydrophobically using methacryloxypropyltrimethoxysilane (MPTMS). TEM indicated that nano-ZnO particles present in nanosphere and have been encapsulated in the PMMA phase. FT-IR confirmed that MPTMS reacted with the nano-ZnO particle and copolymerized with MMA. It was clearly found from SEM that ZnO nanoparticles can be homogeneously dispersed in the PVC matrix. The absorbance spectrum of the nanocomposite polymer suggested that increasing the amount of nano-ZnO in composite particles could enhance the UV-shielding properties of the polymers. The nano-ZnO/PMMA composite particle could eliminate aggregation of ZnO nanoparticle and improve its compatibility with organic polymer. This means that the composite particles can be widely applied in lots of fields.