聚四氟乙烯辐射接枝苯乙烯-丙烯酸的研究

本文采用共辐照工艺,在20°—40℃范围内研究了聚四氟乙烯辐射引发接枝苯乙烯-丙烯酸的动力学。找到了接枝温度与临界辐照强度的关系。高于临界辐照强度,接枝发生在表面,反之,接枝发生在整体。借光学显微镜和扫描电子显微镜研究了接枝膜的断面和表面结构。表面接枝膜的接枝量约1毫克/厘米~2,平均粘结强度高达100公斤/厘米~2以上。表面接枝膜的电性能与未接枝的聚四氟乙烯相仿。可知聚四氟乙烯表面辐射接枝苯乙烯-丙烯酸可用作强粘结强度的结构材料或电子元件的粘结密封材料。     

辐照聚甲苯硫醚的研究

用电子束在室温室气中对聚甲苯硫醚（ＰＭＰＳ）进行了辐照．用ＸＰＳ、ＩＲ、ＤＳＣ和ＴＧ对辐射交联及伴随的化学变化进行了表征．结果表明，ＰＭＰＳ的辐射交联发生在苯环上，ＸＰＳ能用于高聚物交联的表征．     

含有机硅多嵌段及其接枝共聚物的表面组成

利用ＸＰＳ对聚二甲基硅氧烷与聚砜或／和聚对羟基苯乙烯组成的二元和三元多嵌段和接枝共聚物及其共混物进行了研究。结果表明溶液成果的聚合物样品的表面都存在有机硅富集，共混物的表面富集程度等于接枝共聚物，更高于多嵌段共聚物，讨论了有机硅含量和键接结构对有机硅表面富集的影响。     

等离子体引发聚丙烯接枝苯乙烯共聚物的合成及性能

将等离子体接枝技术用于聚丙烯接枝苯乙烯共聚物的合成。ＦＴ－ＩＲ，ＳＥＭ及ＸＰＳ证明所得产物为接枝共聚物。研究了不同等离子体处理体系压强，处理功率，反应瓶不同直径体积，不同接枝聚合反应时间，温度对接枝率的影响。     

γ-射线辐照接枝制备几种功能性高分子材料

概述了近几年来本研究组在高分子材料辐照接枝制备功能性高分子材料方面的研究进展.分别以丙烯酸、顺丁烯二酸、苯乙烯接枝聚四氟乙烯纤维,制备了不同酸性的聚四氟乙烯功能纤维.以N-异丙基丙烯酰胺接枝壳聚糖制备温度及pH敏感材料,获得了性能特异的新型功能性高分子材料.报道了该类新型功能高分子材料的各种特异性能,如对金属离子优异的分离、吸附和解吸性能、超强酸性和一系列潜在用途.     

辐射接枝聚四氟乙烯的形态结构与结晶性质

<正> 辐射接枝是高聚物改性的重要方法,它特别适用于一般的化学方法难以实现改性的高聚物,如聚四氟乙烯(PTFE)利用辐射接枝改进粘附性取得较好的效益。 不久以前,Yamakowa等人曾对辐射接枝聚乙烯的结构作了讨论。本文用光学显微镜和X-射线等方法对PTFE辐射接枝苯乙烯(St)-丙烯酸(AA)接枝共聚物的超分子     

苯乙烯/马来酸酐和苯乙烯/甲基丙烯酸二甲氨基乙酯二元体系在聚四氟乙烯多孔膜上的γ辐射接枝

在氮气的氛围下用γ辐照的方法在聚四氟乙烯多孔膜上接枝苯乙烯 马来酸酐、苯乙烯 甲基丙烯酸二甲氨基乙酯二元单体 .并且研究了剂量、剂量率、溶液中单体的浓度和二元单体的摩尔比等条件对接枝率的影响 .探讨了两种单体的竞聚率对接枝率、接枝膜的组成及性能的影响 .结果表明 ,苯乙烯 马来酸酐二元体系对接枝率有协同效应 ,苯乙烯 甲基丙烯酸二甲氨基乙脂二元体系对接枝率表现为加合效应 .制备的二元接枝的聚四氟乙烯多孔膜可以进一步磺化来制备用于质子交换膜燃料电池的质子交换膜 .     

等离子体引发聚丙烯接技苯乙烯共聚物的合成及性能

将等离子体接枝技术用于聚丙烯接枝苯乙烯共聚物的合成．ＦＴ ＩＲ、ＳＥＭ及ＸＰＳ证明所得产物为接枝共聚物．研究了不同等离子体处理体系压强、处理功率，反应瓶不同直径、体积，不同接枝聚合反应时间、温度对接枝率的影响．利用接枝共聚物制备了硫酸钠型离子交换膜，并对其电性能进行了初步探讨．     

苯乙烯在炭黑表面的阴离子接枝聚合研究

利用正丁基锂（ｎ－ＢｕＬｉ）与炭黑（ＣＢ）表面含氧基团反应制得了表面含－ＯＬｉ基团的反应型炭黑，以该炭黑与聚氧乙烯－聚氧丙烯－聚苯乙烯（ＰＥＯ－ＰＰＯ－ＰＳ）多嵌段聚合物组成的阴离子引发体系作活性中心，研究了苯乙烯在炭黑表面的阴离子接枝聚合。ＦＴ－ＩＲ，ＴＥＭ和ＤＳＣ分析表明在接枝炭黑表面存在苯乙烯的聚合物。接枝炭黑在甲苯中有良好的分散稳定性。     

聚氯乙烯-g-聚甲基丙烯酸-2-羟乙酯共聚物的合成和表征

聚氯乙烯 (ＰＶＣ)是常用医用高分子材料之一 ,可以制作储血袋、导液管、人工尿道等 .ＰＶＣ亲水性差 ,影响其生物相容性 .采用亲水性单体与ＰＶＣ接枝共聚是提高ＰＶＣ亲水性的重要方法[1] .Ｋｒｉｓｈｎａｎ等[2 ] 对Ｃｏ60 辐照下ＰＶＣ接枝Ｎ 乙烯基吡咯烷酮进行了研究 .Ｓｉｎｇｈ等[3～ 5] 采用辐照引发甲基丙烯酸在ＰＶＣ薄膜的接枝反应 ,对接枝动力学、接枝后薄膜表面形态、溶胀和抗凝血性等进行了研究 .Ｇｏｌｄｂｅｒｇ等[6] 采用辐照引发甲基丙烯酸2 羟乙酯 (ＨＥＭＡ)在ＰＶＣ薄膜上的接枝 .Ｌｅｅ等[7]采用溶液接枝共聚制备了…     

Surface structures of fluoropolymer,polyolefin and polyester films after modification by graft polymerization

Pristine and argon plasma pretreated polytetrafluoroethylene (PTFE), polystyrene (PS), high-density polyethylene (HDPE) and poly(ethylene terrephthalate) (PET) films have been subjected to near-UV light-induced graft polymerization with water-soluble acrylamide (AAm), the sodium salt of styrene sulfonic acid (NaSS), acrylic acid (AAc) and N,N-dimethylaminoethylmethylacrylate (DMAEMA) monomers. The structure and composition at the substrate surface with grafted polymer were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). In most cases, the density of surface grafting is enhanced by plasma pretreatment. For each polymer substrate with a substantial amount of grafting, the hydrophilic graft penetrates or becomes partially submerged beneath a thin surface layer of dense substrate chains. This stratified microstructure is consistent with the static secondary ion mass spectroscopy (SIMS) and Ar⁺ beam depth profiling results. The two latter techniques also suggest that when the grafted polymer has a bulky substituent, there is less efficient penetration of the grafted polymer below the surface.     

THE PREPARATION AND CHARACTERIZATION OF SBR／PS CORE-SHELL PARTICLES BY GAMMA IRRADIATION

A kind of core(SBR)-shell(PS) particles was synthesized by using SBR latex and grafting with St under gamma irradiation. The influences of absorbed dose and dose rate on the grafting yield of PS on SBR seed latex have been investigated. Results show there was a transition layer which contained the SBR/PS graft copolymer between the SBR core and PS shell. Dynamic laser scattering (DLS) and differential scanning calorimetry (DSC) results confirm the existence of grafted polystyrene, and transmission electron microscope (TEM) observation verifies the core-shell structure of SBR-g-PS latex. Such SBR/PS core-shell latex could be processed easily to ultrafine rubber powders by using spray drying and expected to be used as an impact modifier for PS.     

CHARACTERIZATION OF RADIATION GRAFTING DEGREE OF POLYSTYRENEg-ACRYLIC ACID BY XPS

In this work, characterization of radiation grafting degree of polystyrene-g-acrylic acid by XPS was studied. It is found that along with the main peak C_(1s) there is a photoelectron peak at 289.0 eV that appears to be C_(1s) of-(?)-OH group and shows the presence ofpolyacrylic acid grafted on the polystyrene The grafting degree obtained by XPS is in agreement with that from the gravimetric method.     

Pre-irradiation induced grafting of styrene into crosslinked and non-crosslinked polytetrafluoroethylene films for polymer electrolyte fuel cell applications. I: Influence of styrene grafting conditions

Crosslinked and non-crosslinked polytetrafluoroethylene (PTFE) films [RX-PTFE and V-PTFE films, respectively], were irradiated in air at room temperature using γ-rays from a ⁶⁰Co source. The irradiated films were grafted with styrene in liquid phase. The grafting of styrene into PTFE films was proved by FT-IR spectroscopy. The influence of the reaction temperature and pre-irradiation doses on the resulted degree of grafting was discussed. The grafting speed and the degree of grafting were determined by the reaction temperature and pre-irradiation doses. The apparent activation energies were calculated as 39.7 kJ/mol for RX-PTFE films and 59.5 kJ/mol for V-PTFE films. The dependence index on absorbed doses at pre-irradiation for RX-PTFE films is 0.66, and for V-PTFE films it is 1.57. The geometric size changes of the grafted films were measured and discussed. Interestingly, the thickness of the grafted films was strongly influenced by the reaction temperature. The tensile strength and the elongation at break of the non-grafted and grafted RX-PTFE and V-PTFE films were measured. The grafted films then are sulfonated by chlorosulfonic acid for polymer electrolyte fuel cell (PEFC) applications and the highest IEC value gained is over 3. The analysis of the sulfonated films are now in progress.     

Corona discharge treatment route for the grafting of modified ��-cyclodextrin molecules onto cellulose

Corona discharge treatment (CDT) was implemented to attempt to graft a modified ??-cyclodextrin (??-CD) onto cellulose. The occurrence of grafting was indirectly proven by gravimetric analyses, X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). Besides, the effect of CDT onto cellulosic substrate was studied using SEM and XPS. It appeared that surface roughness increased with the treatment time as a consequence of an etching effect and that surface oxidation took place as evidenced by the creation of hydroxyl and carboxyl groups. These functional groups are not responsible for chemical link between modified ??-CD and substrate. It was assumed that the grafting results from the reaction of double-bonds of modified ??-CD and radicals formed on treated surface, these ones being evidenced by DPPH radical trapping. Moreover the inclusion of a guest molecule is still possible in grafted modified ??-CD giving a new proof of grafting.     

Oligonucleotide Synthesis on Polystyrene-Grafted Poly(tetrafluoroethylene) Support

Supports consisting of a thin layer (2–10%) of polystyrene (PS) grafted onto a poly(tetrafluoroethylene) (PTFE) core are an interesting alternative to controlled pore glass (CPG) carriers in oligonucleotide synthesis. The beads are mechanically stable, do not show significant swelling, and allow effective removal of substrates by short washing steps with organic solvents. PTFE-PS as an organic polymer has generally more hydrophobic properties than inorganic polymer supports and, therefore, is well compatible with organic solvents such as anhydrous MeCN. We found PTFE with a content of 2–3% PS graft to be a very good support for the synthesis of oligonucleotides of extended length. In comparison, PTFE with 5–10% grafted PS is especially useful for large-scale syntheses. Functionalization procedures minimized in the extent of side reactions are described as well as examples for the use of the supports in syntheses of oligonucleotides both on large scale and of extended chain length.     

纳米氧化硅表面阴离子接枝聚合苯乙烯

通过正丁基锂(BL)引发甲基丙烯酰氧丙基纳米氧化硅(MAMSN)与苯乙烯共聚,制备了聚苯乙烯表面接枝纳米氧化硅(PS—g—Silica),并考察了正丁基锂加入量对苯乙烯转化率(C)、接枝率(PG)以及聚苯乙烯分子量(Mn)的影响。实验结果表明,阴离子聚合可以获得比自由基聚合更大的分子量和更高的转化率以及接枝率。     

表面引发的原子转移自由基聚合法在聚偏二氟乙烯表面制备可控的聚甲基丙烯酸甲酯刷

采用表面引发的原子转移自由基聚合法(ATRP)在聚偏二氟乙烯(PVDF)表面制备结构可控的聚甲基丙烯酸甲酯刷。通过碱处理和紫外光照溴代的方法,将ATRP引入到PVDF表面; 然后采用ATRP法将甲基丙烯酸甲酯接枝到溴代的PVDF表面。采用傅里叶变换红外光谱和X-射线光电子能谱对改性前后PVDF表面的结构进行了表征。结果表明甲基丙烯酸甲酯成功地接枝到了PVDF表面。