聚丙烯酰胺纳米复合材料的合成与溶液特性

用长链烷基季铵盐处理蒙脱土进行插层反应得到有机蒙脱土及中间相,然后与丙烯酰胺水溶液聚合,经原位插层复合反应制备聚丙烯酰胺纳米复合材料.优化聚合条件为:单体质量分数25%,氧化剂、还原剂均占单体质量分数0.08%,偶氮引发剂占单体质量分数0.05%,无机中间体含量1.0%,所得产物分子量850万.耐温抗盐实验结果表明,聚...     

MMA体系注凝成型制备氧化铝陶瓷膜的研究

采用有机单体甲基丙烯酸甲酯(MMA)本体聚合制得MMA预聚液,与氧化铝粉体混合后制得陶瓷膜。并对MMA预聚液、陶瓷膜进行了表征。研究结果表明:在温度为90℃,引发剂过氧化二苯甲酰(BPO)用量为0.1%(wt,质量分数),聚合时间11.5min条件下,制得的MMA预聚液黏度适宜,与50%(固相体积分数)氧化铝粉体混合后制得的陶瓷膜表面光滑,结构完整,对分散大红染料的截留率可达98%以上。     

尼龙6/季铵盐/蒙脱土纳米复合材料的分子动力学模拟

通过分子动力学(MD)模拟方法对十六烷基三甲基氯化铵(CTAC)、十六烷基三甲基溴化铵(CTAB)和十八烷基三甲基氯化铵(OTAC)改性蒙脱土(MMT)的尼龙6(PA6)/季铵盐/MMT纳米复合材料共混体系的微观分子结构进行了研究。结果表明,MD模拟平衡后季铵盐分子平铺在MMT上,几乎覆盖了MMT的整个表面,PA6塌缩在季铵盐分子上,没有直接与MMT表面相接触;季铵盐与MMT之间存在强烈的相互作用,季铵盐中的非极性长链烷基通过范德华力与高分子链发生作用,烷基链数越少作用越强;季铵盐中的极性基团(卤素取代基)通过静电力与MMT相作用,取代基电负性越大,作用越强;烷基链数越多,高分子链越容易插入MMT片层中;10 nm~25 nm为季铵盐和PA6相互作用的界面区。     

单体种类对季铵盐羧酸型复鞣固色剂性能的影响

以含有季铵盐和羧基的聚合物为基体,通过水溶液聚合法引入不同单体,考察单体种类对季铵盐羧酸型复鞣固色剂性能的影响。红外光谱(FT-IR)结果表明,不 饱和单体成 功发生了聚 合;X射 线 衍 射(XRD)结果表明,与聚合物基体相比,不同单体的引入均降低了复鞣固色剂的结晶度,提高了高分子链的柔软性;将其应用于绵羊皮服装革的复鞣工序,结果表明,在聚合物基体中引入丙烯酸-2-羟乙酯(HEA)后,坯革的K/S值达到了16.461,耐干湿擦牢度和物理机械性能良好。     

钠基膨润土-AM-AA共聚复合型净水剂的制备及表征

为了改善膨润土的吸附性能和使用性能,文中以钠基膨润土为主体原料,进行了丙烯酰胺(AM)和丙烯酸(AA)聚合制备钠基膨润土-聚丙烯酰胺-聚丙烯酸复合物的研究,并通过对产品和原料进行X射线衍射(XRD)、红外光谱(FT-IR)、扫描电镜(SEM)和热重表征等表征分析,探讨了聚合机理。结果表明,丙烯酰胺和丙烯酸插层进入膨润土层间,在层间发生了聚合反应,所制备的复合物呈现类似吸水树脂的物理形态,在水中不发生解离。复合新型净水剂对Pb2+离子的吸附性能随着膨润土含量的提高而增加,且明显优于钠基膨润土。     

MMA-粉煤灰漂珠体系凝胶注模成型制备多孔陶瓷

以甲基丙烯酸甲酯(MMA)为单体,粉煤灰漂珠为骨料,采用非水基凝胶注模成型工艺制备多孔陶瓷。考察了MMA含量对浆料性能的影响、MMA预聚合方式对浆料成型的影响以及生坯的排胶与烧结方法,并对多孔陶瓷性能进行了表征。研究表明:微波预聚合可缩短诱导期、加速MMA本体聚合;过高的微波功率和引发剂用量使反应加速,不利于聚合稳定;提高预聚合程度有助于缩短浆料固化时间、降低生坯体积收缩;为保证浆料的流动性及生坯的完整性,应将MMA预聚液含量控制在45wt%~60wt%;生坯(MMA 50wt%)在380℃排胶1h、1050℃烧结2h,得到的多孔陶瓷抗弯强度为40.35MPa,显气孔率为42.03%,平均孔径为1.12μm。     

单体种类对季铵盐羧酸型复鞣固色剂性能的影响

以含有季铵盐和羧基的聚合物为基体,通过水溶液聚合法引入不同单体,考察单体种类对季铵盐羧酸型复鞣固色剂性能的影响。红外光谱(FT-IR)结果表明,不饱和单体成功发生了聚合;X射线衍射(XRD)结果表明,与聚合物基体相比,不同单体的引入均降低了复鞣固色剂的结晶度,提高了高分子链的柔软性;将其应用于绵羊皮服装革的复鞣工序,结果表明,在聚合物基体中引入丙烯酸-2-羟乙酯(HEA)后,坯革的K/S值达到了16.461,耐干湿擦牢度和物理机械性能良好。     

原位插层聚合制备纳米复合材料及其在皮革鞣制中应用的研究

通过优化聚二烯丙基二甲基季铵盐（PDMDAAC）的合成工艺,选用二烯丙基二甲基季铵盐（DMDAAC）在不同用量的蒙脱土中原位插层聚合,制备了系列纳米复合材料（PDMDAAC／MMT）。通过单体转化率和聚合物的特性粘度考察不同用量的蒙脱土对单体插层聚合的影响;也进行了采用纳米复合材料应用于皮革预鞣,再用2％标准铬粉鞣制的试验初试。结果表明：蒙脱土的用量为5％时,蒙脱土的层间距、单体转化率、聚合物的特性粘度均达到最大值;蒙脱土用量为4％时,纳米复合材料对坯革的增强效果最明显;同时对坯革透水汽性的负面影响最大。     

丙烯酸酯乳液及其胶膜的制备和性能表征

采用预乳化半连续自生种子乳液聚合的方法以丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)和苯乙烯(St)为主链,丙烯酸(AA)为功能单体共聚制备丙烯酸酯乳液。研究了预乳化时的相比、种子乳液的含量、反应保温时间、硬单体St与MMA的比例、功能单体用量以及软硬单体比例等对乳液性能的影响。研究结果表明,预乳化油水比为1.8∶1、种子乳液质量为预乳化液的1/3、m(St)/m(MMA)=1∶5.5、AA占单体总量为3%时能得到稳定性好、粒径较小且分布较窄、胶膜吸水率低的乳液。通过拉伸测试、差示扫描量热、红外光谱及凝胶渗透色谱等方法,本实验发现随着软硬单体配比增加,乳胶膜的拉伸强度和玻璃化转变温度(Tg)逐渐下降,断裂伸长率逐渐提高。最终得到了粒径分布在114 nm~290 nm之间,相对分子质量分布指数为1.679的目标产物。     

笼型倍半硅氧烷(POSS)基多含氟支链共聚物的制备及其在棉织物上的应用

以季戊四醇为原料,经4步合成了含三条全氟烷基链的丙烯酸酯单体,并以偶氮二异丁腈(AIBN)为引发剂,与八乙烯基笼型倍半硅氧烷(Ov-POSS)和甲基丙烯酸甲酯(MMA)进行自由基溶液聚合获得POSS基含氟共聚物。经核磁共振(~1H-NMR、~(19)F-NMR、~(13)C-NMR)、红外光谱(FT-IR)、元素分析、扫描电子显微镜(SEM)和热重分析(TGA)等进行确证和表征。通过调节3种单体配比,可以获得具有超疏水性、良好疏油性的共聚物(Ov-POSS质量分数10%,MMA与含氟单体摩尔比为4:1),经其处理过的棉织物的对水接触角能够达到156°,对色拉油接触角为124°。     

Novel transparent ternary nanocomposite films of trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania with incorporating networks

Novel ternary nanocomposite trialkoxysilane-capped poly(methyl methacrylate)/zirconia/titania optical films were successfully prepared through a nonaqueous in situ sol–gel method. The acrylic monomers used were methyl methacrylate (MMA) and 3-(trimethoxysilyl)propyl methacrylate (MSMA). PMMA/ZrO₂–TiO₂ incorporating networks formed from alcoholysis of poly(MMA-co-MSMA), zirconium n-butoxide and titanium isoproproxide. The structure, morphology and property of the obtained nanocomposite films were investigated by X-ray photoelectron spectra, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, scanning probe microscopy, thermogravimetric analyses, UV–vis spectrum and spectro-ellipsometer. The nanoparticle size, roughness, thermal stability, UV-shielding property, and refractive index of nanocomposite films increase with the increasing of inorganic contents. The formation mechanism and reason of such improvements were examined and interpreted in a theoretical model. The nanocomposite films possess interesting properties in thermal stability and optical response due to the uniform incorporating networks between organic polymer chains and inorganic clusters.     

乳液插层法制备PMMA/Nd(OH)3/MMT三相纳米复合材料及表征

利用表面活性剂乳液自组装产生模板,以甲基丙烯酸甲酯(MMA)为油相,稀土离子水溶液为水相,混合形成稀土纳米粒子的反胶束微乳液,使稀土粒子均匀分散于油相中,形成热力学稳定的乳液体系,将该乳液插层于有机蒙脱土(O-MMT)的片层间,加入引发剂单体直接进行原位聚合,即制备得产物.通过红外光谱(IR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和差热-热重(TG-DTA)对该复合材料进表征和分析.研究结果表明,利用乳液法制备出热稳定性良好的新型PMMA/Nd(OH)3/ MMT三相纳米复合材料.     

Graphite oxide/poly(methyl methacrylate) nanocomposites prepared by a novel method utilizing macroazoinitiator

Graphite oxide (GO)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared by a novel method utilizing macroazoinitiator (MAI). The MAI, which has a poly(ethylene oxide) (PEO) segment, was intercalated between the lamellae of GO to induce the inter-gallery polymerization of methyl methacrylate (MMA) and exfoliate the GO. The morphological, conductivity, thermal, mechanical and rheological properties of these nanocomposites were examined and compared with those of intercalated nanocomposites prepared by polymerization with the normal radical initiator, 2,2′-azobisisobutyronitrile. The improvement in conductivity by GO was more evident in exfoliated nanocomposites compared to that of intercalated nanocomposites. For example, a conductivity of 1.78 × 10⁻⁷ S/cm was attained in the exfoliated nanocomposite prepared with 2.5 parts GO per 100 parts MMA, which was about 50-fold higher than that of the intercalated nanocomposite. The thermal, mechanical and rheological properties also indicate that thin GO with a high aspect ratio is finely dispersed and effectively reinforced the PMMA matrix in both exfoliated and intercalated nanocomposites.     

软段结构对聚酯型聚氨酯结晶性影响的研究

用３种聚酯二醇ＰＥＡ、ＰＢＡ、ＰＨＡ和ＭＤＩ，以溶液聚合法合成了３个系列的线型嵌段聚氨酯胶粘剂（ＰＥＡＵ、ＰＢＡＵ、ＰＨＡＵ）。以Ｘ－Ｒａｙ衍射法测定了３种聚酯和３个系列聚氨酯的结晶度，讨论了聚酯类型、聚酯分子量、聚氨酯中硬段含量等因素对聚氨酯结晶能力的影响。结果表明，在硬段含量不高（＜２５％）情况下，聚氨酯中的结晶部分主要是由聚酯软段引起的，而聚酯结晶能力大小的次序为ＰＨＡ＞ＰＢＡ＞＞ＰＥＡ，增     

碳纳米管的加入对PMMA强度和导电性能的影响

本文研究了ＰＭＭＡ与碳纳米管的原位复合过程、复合体强度及电学性能，结果表明，碳纳米管与ＰＭＭＡ原位复合时，将参与ＭＭＡ的链式聚合反应，这不仅影响了ＭＭＡ的聚合过程和复合体的强度，而且影响了碳纳米管在基体ＰＭＭＡ中的分散度。适当推迟碳纳米管的加入时间，将提高ＰＭＭＡ的强度，碳纳米管的加入也将提高ＰＭＭＡ的导电性能。     

Dispersion characteristics and properties of poly(methyl methacrylate)/multi-walled carbon nanotubes nanocomposites

The preparation, characterization, and properties of poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotubes (MWCNTs) nanocomposites are described. Nanocomposites have been prepared by melt-blending in a batch mixer. Both unmodified and surface modified MWCNTs have been used for the nanocomposites preparation. Using both unmodified and modified MWCNTs, the effect of surface modification in nanocomposites is investigated by focusing on three major aspects: dispersion characteristics, mechanical properties, and electrical conductivity measurements. Dispersion of the MWCNTs in the PMMA matrix is examined by scanning and transmission electron microscopy that revealed a homogeneous distribution-dispersion of MWCNTs in the PMMA matrix for both unmodified and modified MWCNTs. Thermomechanical behavior is studied by dynamic mechanical analyzer and results showed a substantial improvement in the mechanical properties of PMMA in conjunction to an increase in the elastic behavior. The tensile properties of neat PMMA moderately improved after nanocomposites preparation with both modified and unmodified MWCNTs, however, electrical conductivity of neat PMMA significantly improved after nanocomposites preparation with 2 wt% unmodified MWCNTs. For example, the through plane conductivity increased from 3.6 x 10(-12) S x cm(-1) for neat PMMA to 3.6 x 10(-9) S x cm(-1) for nanocomposite. The various property measurements have been conducted and results have shown that, in overall, surface modifications have very little or no effect on final properties of neat PMMA.     

Synthesis and characterization of <Emphasis Type="Italic">in situ</Emphasis> prepared poly (methyl methacrylate) nanocomposites

Hybrid materials, which consist of organic-inorganic materials, are of profound interest owing to their unexpected synergistically derived properties. These hybrid materials replaced the pristine polymers due to their higher strength and stiffness in the recent years. In the present work, studies concerning the preparation of poly (methyl methacrylate) (PMMA), PMMA/SiO₂, and PMMA/TiO₂ nanocomposites are reported. These nanocomposite polymers were synthesized by means of free radical polymerization of methyl methacrylate using benzoyl peroxide as an initiator in a water medium. Further ‘sol-gel’ transformation based hydrolysis and condensation of Ti and Si alkoxides were used to prepare the inorganic phase during the polymerization process of MMA. Paper presented at the Indo-Singapore symposium on ‘Advanced Functional Materials’, IIT Mumbai, 2006.     

Electrical and mechanical properties of PMMA/reduced graphene oxide nanocomposites prepared via in situ polymerization

We report the effect of filler incorporation techniques on the electrical and mechanical properties of reduced graphene oxide (RGO)-filled poly(methyl methacrylate) (PMMA) nanocomposites. Composites were prepared by three different techniques, viz. in situ polymerisation of MMA monomer in presence of RGO, bulk polymerization of MMA in presence of PMMA beads/RGO and by in situ polymerization of MMA in presence of RGO followed by sheet casting. In particular, the effect of incorporation of varying amounts (i.e. ranging from 0.1 to 2 % w/w) of RGO on the electrical, thermal, morphological and mechanical properties of PMMA was investigated. The electrical conductivity was found to be critically dependent on the amount of RGO as well as on the method of its incorporation. The electrical conductivity of 2 wt% RGO-loaded PMMA composite was increased by factor of 10⁷, when composites were prepared by in situ polymerization of MMA in the presence of RGO and PMMA beads, whereas, 10⁸ times increase in conductivity was observed at the same RGO content when composites were prepared by casting method. FTIR and Raman spectra suggested the presence of chemical interactions between RGO and PMMA matrix, whereas XRD patterns, SEM and HRTEM studies show that among three methods, the sheet-casting method gives better exfoliation and dispersion of RGO sheets within PMMA matrix. The superior thermal, mechanical and electrical properties of composites prepared by sheet-casting method provided a facile and logical route towards ultimate target of utilizing maximum fraction of intrinsic properties of graphene sheets.     

In vitro adhesion and biocompatability of osteoblast-like cells to poly(methylmethacrylate) and poly(ethylmethacrylate) bone cements

A bone cement, poly(ethylmethacrylate)/n-butylmethacrylate (PEMA/nBMA) has been developed with lower exotherm and monomer leaching compared to the traditional poly(methylmethacrylate)/methylmethacrylate (PMMA/MMA) cement. This study compares the in vitro biological response to the cements using primary human osteoblast-like cells (HOB). Cell attachment was qualified by immunolocalization of vinculin and actin cytoskeleton, showing more organization on PEMA/nBMA compared to PMMA/MMA. Proliferation was assessed using tritiated thymidine incorporation, and phenotype expression determined by measuring alkaline phosphatase (ALP) activity. An increase in proliferation and ALP activity was observed on PEMA/nBMA compared to PMMA/MMA. The results confirm the biocompatability of PEMA/nBMA, and an enhanced cell attachment and expression of differentiated cell phenotype.     

聚氨酯/聚甲基丙烯酸甲酯/有机蒙脱土纳米复合材料的制务、结构与性能

首次将插层纳米复合技术与互穿聚合物网络（IPN）技术相结合,通过同步插层聚合法制备了聚氨酯/聚甲基丙烯酸甲酯/有机蒙脱土（PU/PMMA/OMMT）纳米复合材料.XRD、SEM、TGA等研究表明,在聚氨酯/有机蒙脱土（PU/OMMT）体系中蒙脱土以40～700 nm的团聚体不均匀地分散在聚氨酯基体中,且部分蒙脱土被插层,其层间距增加了0.95nm,体系为插层型纳米复合材料.PU/PMMA/OMMT体系中蒙脱土以20～80nm的粒子分布于聚合物基体中,且蒙脱土的插层效果显著,是PU/OMMT体系的2.5倍,形成了插层型纳米复合材料.同时,蒙脱土的加入使得聚氨酯和聚甲基丙烯酸甲酯的互穿聚合物网络（PU/PMMA-IPN）体系中PU相与PMMA相间相分离更明显,塑性相畴粒子尺寸显著增加,且各相中两组分相互作用加强,分布更均匀.PU/PMMA/OMMT纳米复合材料的热稳定性高于其他材料.同时对其力学性能进行了研究,发现其力学性能明显优于聚氨酯、基于聚氨酯和PU/PMMA-IPN和PU/OMMT纳米复合材料.