聚乙二醇在稻草热塑性改性中的应用

采用超声微波共辐射技术使聚乙二醇(PEG)在稻草(RS)纤维发生接枝共聚反应。考察了微波功率、超声功率、时间、温度、以及PEG用量对改性程度的影响,获得最佳接枝条件。RS-MDI接枝过程的最佳条件为:稻草与PEG质量比1∶2;微波功率300W,超声波功率270W,反应温度60℃,反应时间60min;RS-MDI与PEG接枝过程的最佳条件为:微波功率300W,超声功率360W,温度60℃,时间60min。FT-IR、SEM、XRD和DSC表征结果表明改性稻草的结构发生改变,并获得了预期的热塑性。稻草接枝共聚物可以在不加任何增塑剂的情况下压制成板。     

聚碳酸酯聚氨酯膜表面构建新型磺铵两性结构及其表征

用聚乙二醇为原料合成N,N'-二甲基甘氨酸单羟基聚乙二醇酯(APEG),并对每步合成的产物用傅立叶变换红外光谱(FTIR)和1H-NMR表征.聚氨酯表面分别引入多氨基聚合物(聚丙烯酰胺和氨基硅油),再接枝APEG,最后在聚氨酯膜表面进行与丙磺酸内酯的开环反应,实现末端带磺铵两性离子聚乙二醇在聚氨酯表面的固定.采用环境扫描电镜(SEM)观察聚合物膜的表面形貌,用光电子能谱(XPS)分析聚合物膜表面元素含量.结果表明:合成的APEG与预定结构一致,通过此法接枝后聚合物膜表面S原子分数分别达1.9%,0.5%,磺铵两性结构成功构建到聚合物膜表面,并且提高了接枝率.     

淀粉接枝丙烯腈共聚物的微波皂化

通过微波加热，使淀粉接枝丙烯腈共聚物在氢氧化钠水溶液中水解，制得高吸水性树脂。对反应时间、微波功率、氢氧化钠溶液体积对水解反应的影响进行了探讨。实验表明只需选择９５Ｗ，加碱８％ＮａＯＨ８０ｍＬ，反应时间为１８ｍｉｎ的反应条件即能制得高吸水性树脂，与常规皂化反应比较，微波加热能大大加快反应速度。     

聚砜膜的低温等离子体改性及其在膜式氧合器的应用

采用低温等离子体技术对用于膜式氧合器的聚砜(PSf)膜进行表面改性,通过接枝聚乙二醇(PEG)和肝素以改善其血液相容性.系统研究了接枝的PEG分子量及不同等离子体处理条件对改性效果的影响.研究结果表明,当PEG分子量为6 000,等离子预处理功率为150W,预处理时间为2min,处理气体为氩气(Ar)时,改性效果最佳,接触角明显降低,蛋白吸附显著减少.膜的汽液双侧传输性质测试结果表明,改性后的PSf膜保留了初始膜的气体传输性能,基本达到了医用人工肺材料的标准.     

水溶性聚氨酯热熔胶的制备

目的制备水溶性聚氨酯热熔胶。方法用聚乙二醇(PEG)和甲苯二异氰酸酯(TDI)为原料,制备水溶性聚氨酯热熔胶,研究了PEG的相对分子质量、TDI滴加温度、原料配比和反应时间等对水溶性聚氨酯热熔胶性能的影响。结果当PEG8000,PEG600,PEG200,乙二醇和TDI的摩尔比为1∶1∶0.8∶1∶4,TDI的滴加温度为60～70℃、反应时间为4 h时,所得水溶性聚氨酯热熔胶的软化点为59.5℃、粘接强度为2.668 MPa。结论制备的水溶性聚氨酯热熔胶可以作为电子产品零配件等工业半成品的表面保护膜。     

聚丙烯微孔膜表面接枝聚合丙烯酰胺的改性研究

用化学方法在聚丙烯微孔膜表面接枝丙烯酰胺单体,分别考察了反应温度、单体浓度、反应时间和引发剂浓度等反应因素对接枝率的影响,红外光谱和扫描电镜证实了丙烯酰胺在聚丙烯微孔膜表面的接枝,水接触角测试显示接枝膜具有良好的亲水性,热分析表明接枝膜基本没有改变聚丙烯微孔膜的基体性质.实验发现当反应温度为60℃,单体浓度为10%,反应时间为4h,引发剂浓度为2.0×10-3mol/L时,获得最佳接枝效果.     

聚乙二醇对淀粉原位熔融接枝聚乳酸的影响

研究了在聚乙二醇(PEG)存在下,淀粉与丙交酯的原位熔融接枝反应。较系统地考察了PEG的加入量及分子量的变化对淀粉一聚乳酸原位熔融接枝反应的影响。结果表明,当有PEG存在时,丙交酯可以有效地接枝到淀粉链上,得到淀粉一聚乳酸接枝共聚物。PEG对淀粉的增塑效果是影响淀粉与丙交酯熔融接枝反应至关重要的因素。     

pH响应性乙烯-乙烯醇共聚物分离膜的纳滤特性

具有纳滤特性的pH响应性膜在小分子分离体系中具有广泛应用前景。文中以铸膜液浓度为25%的乙烯-乙烯醇共聚物(EVAL)超滤膜为基膜,接枝具有pH响应性的功能单体甲基丙烯酸二甲氨基乙酯,制备pH响应性EVAL膜,通过考察膜对标准物聚乙二醇(PEG)与无机盐的截留性能,研究其纳滤特性。结果表明,当pH小于pKa时,pH响应性EVAL膜对聚乙二醇(PEG)与无机盐的截留效果均明显高于未接枝膜,接枝率6%的接枝膜对PEG 800、PEG 1000及PEG 2000的截留率均达到90%以上,对二价阳离子的截留率达到80%以上,无机盐的截留顺序为:CaCl_2MgCl_2MgSO_4NaClNa2SO_4。当pH大于pKa时,PEG及无机盐截留率明显下降,膜对PEG 1000的截留率由95.6%降至62.9%,对MgCl_2截留率降至30.6%,截留率及膜水通量变化存在显著的pH响应性。     

等离子体表面接枝改性聚对苯二甲酸乙二醇酯的血液相容性研究

利用等离子体表面接枝改性方法在聚对苯二甲酸乙二醇酯(polyethylene terephthalate，PET)材料表面接枝不同分子量的聚乙二醇(PEG)，体外血液相容性实验表明．接枝了PEG的PET材料的血液相容性与PEG的分子量有关；当接枝的PEG分子量达到6000时，材料的血液相容性最好。     

重质碳酸钙粉体表面微波辅助改性的研究

通过与传统的加热搅拌改性方法的比较,微波辅助改性方法在浊度、浸润度、接触角等方面都优于传统改性方法。实验结果表明,该方法不仅能取代传统的改性加热方式,实现对粉料的表面改性,而且可激发物质内部分子进行超高频振动、摩擦,可实现分子水平上的“搅拌”,这种“激发效应”已开始在高分子合成和固化反应中应用。本文介绍了粉体表面微波辅助改性方法(发明专利申请号:031282598),提出了一套微波辅助改性装置,并以此对重质碳酸钙粉体表面进行异丙基三异硬脂酸基钛酸酯(TTS)改性,实验表明其效果优于传统的加热搅拌改性。     

Grafting of PEG onto lanthanum hydroxide nanowires

Lanthanum hydroxide nanowires were synthesized by hydrothermal method. To reduce the aggregation among lanthanum hydroxide nanowires, an effective surface modification method was proposed by grafting polyethylene glycol (PEG) onto lanthanum hydroxide nanowires. That is, the surface of lanthanum hydroxide nanowires was firstly treated with aminopropyltrimethoxysilane (APTMS), which is a silane coupling agent and introduces functional amino group onto the surface of lanthanum hydroxide nanowires, followed by grafting reaction with PEG-COCl. The obtained nanocomposite was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). Results of FT-IR and TGA showed that the PEG chains had been covalently bonded to the surface of lanthanum hydroxide nanowires. It was found that the increase of molecular weight of the grafted PEG could increase the grafting percentage and hence promote the dispersibility.     

微波辐射分散聚合制备单分散聚甲基丙烯酸甲酯微球

在微波辐射下,以乙醇/水混合溶剂为分散介质,聚乙烯吡咯烷酮为稳定剂,进行了甲基丙烯酸甲酯的分散聚合。利用透射电镜(TEM)、动态激光光散射粒度仪(PCS)研究了微球的形态和粒径大小,探讨了介质中乙醇含量、聚合前期微波功率、引发剂和稳定剂浓度对微球粒径及分布的影响。结果表明,当介质中乙醇质量分数在40%～50%时能得到稳定的聚合物微球。在一定范围内,随着反应前期微波功率的增大,微球粒径增大,粒径分布先减小后变大。与常规加热聚合相比,微波辐射能加快反应速率,提高单体转化率,所得的聚合物微球粒径小,单分散性更好。     

Surface modification of polyurethane for promotion of cell adhesion and growth 1: Surface photo-grafting with N,N-dimethylaminoethyl methacrylate and cytocompatibility of the modified surface

Functional polyurethane (PU) surface was prepared by photo-grafting N,N-dimethylaminoethyl methacrylate (DMAEM) onto the membrane surface. Grafting copolymerization was conducted by the combined use of the photo-oxidation and irradiation grafting. PU membrane was photo-oxidized to introduce the hydroperoxide groups onto the surface, then the membrane previously immersed in monomer solution was irradiated by UV light. The X-ray photoelectron spectroscopy and water contact angle characterized the grafted copolymers and verified the occurrence of graft copolymerization. The results showed that UV irradiation could realize the graft copolymerization effectively. The grafted membrane showed minimal surface morphology. Human umbilical vein endothelium (HUVE) cells were seeded on the grafted surfaces. The performance of the surface in cell attachment correlated with the content of oxygen and nitrogen. Cells were spread more extensive and grown faster on the surface with lower degree of grafting. © 2001 Kluwer Academic Publishers     

Microwave-Assisted Synthesis of a Soluble Single Wall Carbon Nanotube Derivative

The development of a novel procedure based on microwave (MW) heating allowed to obtain a soluble derivative of Single Wall Carbon Nanotubes (SWNTs) by grafting poly(ethylene glycol) (PEG) chains to shortened SWNTs. The use of MW irradiation remarkably enhanced reaction rates compared to similar syntheses based on conventional heating.     

Synthesis of indium tin oxide powder by solid-phase reaction with microwave heating

Indium tin oxide (ITO) powder was synthesized from indium oxide and tin oxide powders by a solid-phase method using microwave heating and conventional heating methods. Microwave heating could reduce the treatment time necessary for the completion of the solid-phase reaction by 1/30. This decrease was attributed to an increase in the diffusion rate of Sn at the local heat spot in the indium oxide formed by microwave irradiation. However, microwave heating also decreased the amount of ITO produced, since the powder layer of the raw material was heated unevenly and had an uneven temperature distribution.Therefore, a microwave heating method including a mixing process was proposed in order to diminish the uneven progress of the ITO synthesis reaction in the powder layer. This revised method could increase the conversion to ITO, which is higher than that obtained by using the conventional heating method. Hence, the electric conductivity of the powder layer obtained by the proposed method was higher than that of the commercially supplied ITO powder layer.     

Kinetic advantages of using microwaves in the emulsion polymerization of MMA

Microwave irradiation has been an interesting alternative for heating systems and several chemical reactions. In polymerization processes, microwaves can enhance reaction rates or improve specific characteristics of the formed polymer. In this work, the use of microwave irradiation in emulsion polymerization reactions has been studied, using a commercial microwave reactor, which is able to perform syntheses under controlled conditions of temperature and power. Methyl methacrylate emulsion polymerization reactions were faster, resulting in smaller polymer particles, in comparison to the conventional heating method (reactions in a jacketed reactor). Different effects were observed in the emulsion polymerization of butyl acrylate. To study the effect of high power microwave irradiation upon the emulsion polymerization, a pulsed irradiation strategy was developed, in which the samples were repeatedly heated within short intervals of time (about 27 s) at the maximum microwave power. A significant reduction of the total time of irradiation was observed in reactions carried out under the pulsed scheme, showing the kinetic advantages of using microwaves in emulsion polymerization processes.     

Synthesis and characterization of pyrite (FeS2) using microwave irradiation

A procedure using microwave irradiation was studied to develop a fast and reliable method for synthesizing pyrite. Pyrite was successfully synthesized within a few minutes via reaction of ferric iron and hydrogen sulfide under the influence of irradiation by a conventional microwave oven. The SEM-EDX study revealed that the nucleation and growth of pyrite occurred on the surface of elemental sulfur, where polysulfides are available. Compared to conventional heating, using microwave energy results in rapid (<1 min) formation of smaller particulates of pyrite. Higher levels of microwave power can form pyrite even faster, but faster reaction can lead to the formation of pyrite with defects.     

瓜尔胶接枝高吸水性树脂的微波法合成

通过微波辐射法将丙烯酸和丙烯酰胺接枝到瓜尔胶的主链上,得到吸水性能优良的高吸水性树脂GAM。研究了微波辐射功率、辐射温度,辐射时间及丙烯酰胺用量对树脂吸液性能的影响规律,得到最佳工艺参数,此时树脂的最高吸水率为1454g/g,吸生理盐水率为169g/g,接枝率为980%。热重分析表明该高吸水性树脂耐热性优于瓜尔胶,证实发生了接枝聚合反应。     

微波辅助聚氯乙烯-苯酚之间的Friedel-Crafts接枝反应及对聚氯乙烯热稳定性的影响

在四氢呋喃溶液中通过微波辐照实现了聚氯乙烯(PVC)与苯酚的Friedel-Crafts接枝反应;通过紫外分光光度法表征了PVC-g-苯酚接枝物的接枝率,考察了加热方式、反应温度、催化剂用量及反应时间对接枝反应的影响,并通过红外光谱表征了接枝物的结构;通过刚果红试验、热重分析研究了接枝苯酚对PVC热稳定性的影响。结果表明,相同反应时间,水浴加热接枝率仅为0.1,而微波辐照接枝率可达2.12,其优化工艺条件为无水AlCl_3的用量为PVC质量的8%,反应时间30 min,反应温度为65℃;接枝样品的刚果红试验热稳定时间为6 min46 s,比空白PVC延长了3 min,在空气气氛和氮气气氛中的热降解第一阶段活化能比空白PVC分别提高11.2 kJ/mol和13.8 kJ/mol,而在第二和第三阶段,接枝样品的活化能反而低于空白PVC。证明苯酚取代了容易导致PVC降解的活性氯,抑制了PVC热降解的第一阶段,即脱HCl反应,提高了PVC的热稳定性。     

表面紫外光接枝润滑改性医用聚氨酯材料

用紫光直接引发亲水性单体Ｎ－乙烯吡咯烷酮、丙烯酰胺在医用聚氨酯表面进行接枝反应,可以提高ＰＵ表面的润滑性。研究了影响接枝密度、摩擦系数的因素,测定了单位表面积吸水率、水接触角。扫描电子显微镜观察发现,接枝反应后材料形成了新表面形貌。