常压聚合制备壁厚均匀的微胶囊发泡剂

采用预分散、常压悬浮聚合法制备以聚(丙烯腈-co-甲基丙烯酸酯)为外壳,异辛烷为芯材的微胶囊发泡剂(TEMs)。制备的TEMs壁厚均匀,呈现完整“核-壳”结构的球形,发泡性能良好。微胶囊发泡剂的平均粒径约28.5μm,粒径分布较窄,芯材含量约为23%,起始发泡温度98～120℃,发泡体积为4.5倍。文中研究了分散剂类型、单体和交联剂对微胶囊发泡剂的形貌和发泡性能的影响,使用无机分散剂(20 g Mg(OH)_2,70 g Na Cl,15 g MgCl_2)时,分散效果较好;当AN与MMA的质量比为1:1时,能得到球形较完整的TEMs;添加不同含量的1,4-丁二醇二甲基丙烯酸酯(BDDMA)交联剂时,包裹发泡剂的含量随着BDDMA含量的增加而减少,发泡温度随着BDDMA含量的增加而升高。     

常压聚合制备壁厚均匀的微胶囊发泡剂EI北大核心CSCD

采用预分散、常压悬浮聚合法制备以聚(丙烯腈-co-甲基丙烯酸酯)为外壳,异辛烷为芯材的微胶囊发泡剂(TEMs)。制备的TEMs壁厚均匀,呈现完整"核-壳"结构的球形,发泡性能良好。微胶囊发泡剂的平均粒径约28.5μm,粒径分布较窄,芯材含量约为23%,起始发泡温度98～120℃,发泡体积为4.5倍。文中研究了分散剂类型、单体和交联剂对微胶囊发泡剂的形貌和发泡性能的影响,使用无机分散剂(20 g Mg(OH)_2,70 g Na Cl,15 g MgCl_2)时,分散效果较好;当AN与MMA的质量比为1:1时,能得到球形较完整的TEMs;添加不同含量的1,4-丁二醇二甲基丙烯酸酯(BDDMA)交联剂时,包裹发泡剂的含量随着BDDMA含量的增加而减少,发泡温度随着BDDMA含量的增加而升高。     

水性油墨用室温交联丙烯酸酯乳液的研究

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸为共聚单体,双丙酮丙烯酰胺(DAAM)为功能单体,采用半连续法乳液聚合技术,合成了含有酮羰基的聚丙烯酸酯乳液。以己二酸二酰肼为交联剂,获得的丙烯酸酯乳液在室温贮存时不产生交联反应,而在干燥时由于体系pH值发生变化,在酸的催化下可固化成膜。结果表明,加入3%的DAAM制得的丙烯酸酯乳液,固含量达50%左右,粒径主要分布在68.1 nm左右,且分布范围较窄,室温交联胶膜透明度、光泽度高,成膜速度快,各项性能优异。     

甲基丙烯酸乙酰乙酰氧基乙酯改性丙烯酸酯乳液压敏胶的制备及其性能

采用预乳化半连续工艺合成了乙酰乙酰氧基丙烯酸酯压敏胶乳液,以乙二胺为交联剂对其进行了交联改性。探讨了交联单体甲基丙烯酸乙酰乙酰氧基乙酯(AAEM)用量对乳液及胶膜压敏粘接性能的影响。研究结果表明:随着AAEM含量的增加,乳液的粒径变大,乳胶膜耐水性能显著提高。当AAEM用量为单体总量的3%(wt,质量分数)时,所制备的压敏胶带具有很好的压敏粘接性能平衡和耐高温性能。     

聚(丙烯酸盐共聚丙烯酰胺)/膨胀蛭石高吸水性复合材料的制备

以N,N'-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,丙烯酸和丙烯酰胺为单体,采用新型溶液聚合法制备了聚(丙烯酸盐共聚丙烯酰胺)/膨胀蛭石高吸水性复合材料.考察了交联剂用量、引发剂用量、单体浓度、中和度、反应温度、膨胀蛭石含量及单体质量比对吸水倍率的影响,试验结果表明:当膨胀蛭石含量为20 wt%时,交联剂用量为0.04 wt%,引发剂为1.3 wt%,中和度为80%,单体浓度为50 wt%,反应温度为80℃,吸水倍率与吸收0.9wt%的NaCl溶液倍率分别为1262 g/g和92 g/g.探讨了添加矿物提高其耐盐性的机理.     

坡缕石/聚丙烯酸钠高吸水保水复合材料的制备与性能研究

采用水溶液聚合法,以丙烯酸为单体,过硫酸钾为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,制备出了坡缕石/聚丙烯酸(钠)高吸水保水复合材料,并采用筛网法测试了产品的吸液性能.通过单因素实验,系统地研究了矿物含量、交联剂用量、引发剂用量、单体中和度等聚合条件对复合材料吸蒸馏水倍率和0.9%NaCl溶液倍率的影响.制备出的坡缕石/聚丙烯酸(钠)复合材料具有较高的吸液倍率及良好的耐盐性.     

双马来酰亚胺交联单分散聚苯乙烯微球的制备及表征

采用分散聚合法,以苯乙烯为单体,二苯甲烷双马来酰亚胺(BDM)为交联剂,制备了单分散交联聚苯乙烯微球(St/BDM)。研究了分散聚合反应中单体(St)、引发剂(AIBN)、分散剂(PVP)、交联剂(BDM)用量对微球粒径和粒径分布的影响。通过优化反应条件,合成了平均粒径为3.03μm(ε=0.05)的单分散交联聚苯乙烯微球。热稳定性分析和耐溶剂性实验结果表明,二苯甲烷双马来酰亚胺(BDM)交联的聚苯乙烯微球热稳定性和耐溶剂性能比线性的聚苯乙烯微球有了很大的提高。当失重5%时,聚合物的热分解温度由交联前的306℃上升到交联后的328℃。     

膨胀蛭石/聚(丙烯酸钾-丙烯酰胺)高吸水性复合材料的制备、性能及表征

以N,N'-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,丙烯酸和丙烯酰胺为单体,采用新型水溶液聚合法合成了膨胀蛭石/聚(丙烯酸钾-丙烯酰胺)高吸水性复合材料.考察了交联剂用量、引发剂用量、单体浓度、中和度、反应温度、单体质量比及膨胀蛭石含量对吸水倍率的影响,试验结果表明,当蛭石含量为30%(相对单体质量,下同)时,交联剂用量为0.04%,引发剂为1.1%,中和度为75%(相对丙烯酸物质的量),单体浓度为50%,反应温度为75℃,吸水倍率最高可达1048g/g.最后,采用SEM、IR对其结构及组成进行了表征.     

核壳结构丙烯酸酯共聚物的制备及对聚碳酸酯的增韧

采用半连续乳液聚合方法制备了聚丙烯酸丁酯/聚甲基丙烯酸甲酯(PBA/PMMA)核壳结构乳液,经处理制得丙烯酸酯共聚物(ACR),再用ACR对聚碳酸酯(PC)进行增韧改性。研究了引发剂用量、乳化剂配比和用量、交联单体的用量对聚合物乳液的影响,以及ACR含量、核壳比、乳化剂用量和交联单体等对共混物力学性能的影响,并用扫描电镜对共混物冲击断面形貌进行了研究。实验结果表明,随乳化剂用量的增大,乳胶平均粒径减小。在乳化剂用量一定时,随乳化剂中OP-10的增加,乳胶平均粒径增大。在核壳结构乳液中核壳质量比为75/25,交联单体用量为8%,乳化剂用量为3%的条件下,共混物中ACR质量分数为6%时,共混物缺口冲击强度最大,使用交联单体二甲基丙烯酸丁二醇酯(BDDMA)的共混物缺口冲击强度是使用交联单体二甲基丙烯酸乙二醇酯(EGDMA)的共混物缺口冲击强度的2倍。随着ACR含量的增加,PC/ACR的缺口冲击强度增加,拉伸强度和弯曲强度略有下降。扫描电镜表明,ACR在PC/ACR中分散粒径大于乳胶粒径。     

优化阿魏酸印迹微球的制备条件及其分子识别性能

以阿魏酸(FA)为模板分子、乙二醇二甲基丙烯酸酯(EDMA)为交联剂、丙烯酰胺(AM)为功能单体、偶氮二异丁腈(AIBN)为引发剂,制备的分子印迹聚合物微球对阿魏酸具有高选择性.通过优化制备条件获得阿魏酸分子印迹聚合物微球(MIPs),并对其结构、形貌及热稳定性进行表征.结果表明,模板分子为功能单体,交联剂的最佳比例为...     

Fabrication of microcellular SiCN ceramics from templated polyvinylsilazane with expandable microspheres

The microcellular SiCN ceramics with high porosity and high surface area were fabricated from polysilazane as a viscous SiCN ceramic precursor and expandable microspheres as a self-sacrificial template. The fabrication steps were composed of (1) forming of expandable microsphere compact, (2) infiltrating polysilazane into the compact, (3) foaming and curing, (4) pyrolysis in N2 gas. The microcellular structures and properties of the obtained ceramic products depended on the foaming and curing conditions as well as the pyrolysis temperature. When foamed and cured at 120 degrees C for 30 min, then pyrolyzed at 1000 degrees C in N2, the microcellular product exhibited the largest cell size 9.3 microm with the lowest cell densities 2.2 x 108 cells/cm2, 93% of porosity and surface area of 356 m2/g. Furthermore, the higher temperature pyrolysis at 1300 degrees C induced significant change in the microcellular morphology by reducing the cell size with thicker wall and the cell density. Finally, it demonstrated an efficient way of manufacturing highly porous microcellular ceramics with no etching process using a polyvinylsilazane and expandable microspheres for catalytic supporting application.     

PLLA-PEG-PLLA/Fe_3O_4磁性微球的制备及性能

以聚乙二醇为引发剂,L-丙交酯为单体,开环聚合得到聚乳酸-聚乙二醇三嵌段共聚物(PLLA-PEG-PLLA),采用溶剂挥发法制备了PLLA-PEG-PLLA/Fe_3O_4磁性微球,并通过扫描电镜对其形态进行了表征。利用振动样品磁强计和Tg研究了微球的磁含量和磁性能,结果发现,相同粒径不同磁含量的磁性微球,磁含量越高,升温速率越快,当磁含量为70.57%时,升温速率最快,能达到磁热疗的有效温度42℃。对于磁含量相同,粒径不同的微粒,粒径越小,升温速率越快,粒径约为10μm时升温速率最快。     

单分散纳米二氧化硅微球的制备及羧基化改性

采用改进工艺条件的Stober法制备纳米SiO_2微球.用场发射扫描电镜(FESEM)分析了纳米二氧化硅的形貌、粒径.结果表明,通过温度梯度法和控制氨水浓度变化制备出高圆度、单分散、粒径可控的纳米级二氧化硅微球.用KH-550硅烷偶联剂和丁二酸酐对纳米二氧化硅表面羧基化改性.采用X射线能谱仪(EDS)、热重(TGA)、傅里叶红外(FTIR)等手段对改性后纳米二氧化硅的结构、元素种类及含量进行了表征.结果表明,纳米二氧化硅表面成功接枝了羧基官能团.     

Formulation and Characterization of Formaldehyde Cross-linked Degradable Starch Microspheres Containing Terbutaline Sulfate

ABSTRACT

Preparation of starch microspheres using epichlorohydrin is a time consuming method and requires around 18 hr for cross-linking reaction. To reduce reaction time, terbutaline sulfate (TBS) loaded degradable starch microspheres (DSM) were prepared using formaldehyde as the cross-linking agent. All microspheres were spherical in shape and had a porous, rough surface with a mean particle size of 18–24 μm. Whatever the cross-linking time, it was seen that the release of the TBS was not complete during the release experiments. The influence of enzyme on the degradation of microspheres was moderate. Following intravenous administration, initial uptake of microspheres by the lung was higher than those of other organs.     

Formulation and characterization of formaldehyde cross-linked degradable starch microspheres containing terbutaline sulfate

Preparation of starch microspheres using epichlorohydrin is a time consuming method and requires around 18 hr for cross-linking reaction. To reduce reaction time, terbutaline sulfate (TBS) loaded degradable starch microspheres (DSM) were prepared using formaldehyde as the cross-linking agent. All microspheres were spherical in shape and had a porous, rough surface with a mean particle size of 18-24 microm. Whatever the cross-linking time, it was seen that the release of the TBS was not complete during the release experiments. The influence of enzyme on the degradation of microspheres was moderate. Following intravenous administration, initial uptake of microspheres by the lung was higher than those of other organs.     

交联剂对HDPE/竹粉复合发泡材料性能的影响

以高密度聚乙烯(HDPE)为基体塑料,偶氮二甲酰胺与氧化锌复配物为发泡剂,过氧化二异丙苯(DCP)为交联剂,采用两步模压发泡法制备了HDPE/竹粉复合发泡材料,并研究了交联剂对复合材料密度和回弹性能、发泡性能、力学性能的影响。结果表明:当交联剂的添加质量分数为0.6%时,HDPE/竹粉复合发泡材料的密度达最小值,为0.054 g/cm~3;回弹率达最大值,为90.5%;当交联剂的添加质量分数为0.4%时,复合发泡材料的泡孔分布相对多而均匀,弯曲强度达最大值,为29.3 MPa,相比未发泡材料约低8.2%,冲击强度为6.8 k J/m~2,相比未发泡材料约低16%。     

Development of novel interpenetrating network gellan gum-poly(vinyl alcohol) hydrogel microspheres for the controlled release of carvedilol

Novel interpenetrating polymeric network microspheres of gellan gum and poly(vinyl alcohol) were prepared by the emulsion cross-linking method. Carvedilol, an antihypertensive drug, was successfully loaded into these microspheres prepared by changing the experimental variables such as ratio of gellan gum:poly(vinyl alcohol) and extent of cross-linking in order to optimize the process variables on drug encapsulation efficiency, release rates, size, and morphology of the microspheres. Formation of interpenetrating network and the chemical stability of carvedilol after preparing the microspheres was confirmed by Fourier transform infrared spectroscopy. Differential scanning calorimetry and x-ray diffraction studies were made on the drug-loaded microspheres to investigate the crystalline nature of the drug after encapsulation. Results indicated a crystalline dispersion of carvedilol in the polymer matrix. Scanning electron microscopy confirmed the spherical nature and smooth surface morphology of the microspheres produced. Mean particle size of the microspheres as measured by laser light scattering technique ranged between 230 and 346 µm. Carvedilol was successfully encapsulated up to 87% in the polymeric matrices. In vitro release studies were performed in the simulated gastric fluid or simulated intestinal fluid. The release of carvedilol was continued up to 12 h. Dynamic swelling studies were performed in the simulated gastric fluid or simulated intestinal fluid, and diffusion coefficients were calculated by considering the spherical geometry of the matrices. The release data were fitted to an empirical relation to estimate the transport parameters. The mechanical properties of interpenetrating polymeric networks prepared were investigated. Network parameters such as molar mass between cross-links and cross-linking density for interpenetrating polymeric networks were calculated.     

Development of Novel Interpenetrating Network Gellan Gum-Poly(vinyl alcohol) Hydrogel Microspheres for the Controlled Release of Carvedilol

Novel interpenetrating polymeric network microspheres of gellan gum and poly(vinyl alcohol) were prepared by the emulsion cross-linking method. Carvedilol, an antihypertensive drug, was successfully loaded into these microspheres prepared by changing the experimental variables such as ratio of gellan gum:poly(vinyl alcohol) and extent of cross-linking in order to optimize the process variables on drug encapsulation efficiency, release rates, size, and morphology of the microspheres. Formation of interpenetrating network and the chemical stability of carvedilol after preparing the microspheres was confirmed by Fourier transform infrared spectroscopy. Differential scanning calorimetry and x-ray diffraction studies were made on the drug-loaded microspheres to investigate the crystalline nature of the drug after encapsulation. Results indicated a crystalline dispersion of carvedilol in the polymer matrix. Scanning electron microscopy confirmed the spherical nature and smooth surface morphology of the microspheres produced. Mean particle size of the microspheres as measured by laser light scattering technique ranged between 230 and 346 µm. Carvedilol was successfully encapsulated up to 87% in the polymeric matrices. In vitro release studies were performed in the simulated gastric fluid or simulated intestinal fluid. The release of carvedilol was continued up to 12 h. Dynamic swelling studies were performed in the simulated gastric fluid or simulated intestinal fluid, and diffusion coefficients were calculated by considering the spherical geometry of the matrices. The release data were fitted to an empirical relation to estimate the transport parameters. The mechanical properties of interpenetrating polymeric networks prepared were investigated. Network parameters such as molar mass between cross-links and cross-linking density for interpenetrating polymeric networks were calculated.     

乙烯基胶原蛋白微球的制备及其应用

为了得到带有"-C=C-"的胶原蛋白微球,我们使用甲基丙烯酸酐对胶原蛋白改性,再采用乳化交联法将改性胶原蛋白制备成乙烯基胶原蛋白微球(CMAs),并将微球应用到尼龙基材上.研究了CMAs的制备条件,使用傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、激光粒度分析仪等对CMAs和乙烯基胶原蛋白微球/尼龙(Nylo...     

双马来酰亚胺泡沫的微观形貌与结构控制研究

以偶氮二甲酰胺(AC)为发泡剂制备了改性双马来酰亚胺(BMI)泡沫,用扫描电镜(SEM)对泡沫的微观形貌进行观察,研究泡沫的发泡过程及不同条件下泡沫的泡孔结构,包括密度、孔径、单位体积的泡孔数目、发泡倍率等。结果表明:改性的BMI泡沫是一种闭孔结构泡沫,其构型为排泄型十二面体。可通过发泡体系的黏度、温度和发泡剂含量控制BMI泡沫的结构,随发泡体系黏度的增加,泡沫密度,成核密度N0和单位体积的泡孔数目Nf增加,泡孔直径减小,均匀性变好。泡沫密度随发泡剂AC含量提高而降低,当AC含量超过7%(质量分数)时,泡沫密度反而上升。随发泡温度提高,泡沫密度降低,孔径增大,泡沫成型稳定性变差。