引发转移终止剂技术合成含有聚异戊二烯链段的三嵌段共聚物

含聚异戊二烯 (ＰＩＰ)链段的嵌段共聚物有着广泛的应用[1～ 3 ] ,有关它的合成、性能表征及应用方面的研究一直是学术及工业界的研究热点 .传统上 ,含有ＰＩＰ链段的嵌段共聚物用活性负离子聚合的方法来合成 ,例如 :聚苯乙烯 聚异戊二烯嵌段共聚物[3 ,4 ] .这是由聚合物增长链端的特殊活性所决定的 ,采用活性负离子聚合方法 ,不但能很好地控制共聚物的分子量和分子量分布 ,而且能控制共聚物中各组分的比例 .但是 ,负离子聚合通常需在较苛刻的条件下进行 ,如低温高真空、高纯度的单体和溶剂 ,而且能用于负离子聚合的单体也有限 .相对而言 ,…     

硫氰化钠对过氧化物引发丙烯腈水溶液聚合的影响

<正> 关于硫氰化物对丙烯腈聚合的影响,早期的报道认为对过硫酸盐引发丙烯腈水溶液聚合时,硫氰化钾起阻聚作用.但丙烯腈在浓硫氰化钠水溶液中,可顺利地用偶氮双异丁腈(AIBN)、光、叔丁基过氧化氢(TBH)或TBH-醇胺引发聚合,在这些聚合反应中硫氰化钠无阻聚或缓聚作用.为了弄清硫氰化钠的影响,我们比较系统地研究硫氰化钠对丙烯腈水溶液聚合的影响.实验结果表明,其影响与所用的引发剂有关.如用TBH时,硫氰化钠起活化作用,缩短反应的诱导期,提高聚合速度与转化率,30—50℃     

溶胶-凝胶法合成聚甲基丙烯酸甲酯/二氧化钛杂化聚合物材料

由共聚合在PMMA聚合物链段上引入了－Si(OR)₃功能团,通过溶胶－凝胶过程合成了PMMA/TiO₂杂化聚合物材料.溶剂抽提结果表明有化学键存在的杂化材料体系中凝胶的含量很高.通过FTIR测试对材料结构进行了分析,由TGA、DSC测试分析了杂化材料体系中无机组份的含量对材料性能的影响.     

控制/活性自由基聚合的进展

1活性自由基聚合1.1控制/活性自由基聚合自由基聚合是工业生产乙烯基类聚合物的重要方法。因其可聚合的单体种类多,能以水为介质进行悬浮和乳液聚合,反应温和,聚合工艺操作简便,重现性好,自20世纪50年代以来已成为工业生产高分子产品的重要技术。由于自由基聚合中增长链自由基很活泼,容易发生双分子偶合或歧化终止以及链转移反应,得到无活性的聚合物,聚合产物分子量分布宽、分子量和结构不可控制,从而影响聚合物的性能,需要改进。活性自由基聚合起始于20世纪80年代,在90年代取得了突破性进展,并成为当今高分子化学研究的热点之一。由于它能…     

Effects of Template Contents on the Physicochemical Sorption Properties of Zr—Incorporated Mesoporous Titania Materials

Zr-Incorporated mesoporous titania materials were prepared via nonsurfactant templated sol-gel process of zirconium(IV) butoxide(ZBT) and titanium(IV) butoxide(TBT) in the presence of urea molecules as template or pore forming agent.The effcets of template contents on the pore parameters of the materials synthesized with fixed Zr incorporation contents were investigated by mitrogen adsorption-desrption measurements,powder X-ray diffraction(XRD) study and transmission electron microscopy(TEM).The changes of template contents play significant roles on the pore parameters at low incorporsation content of Zr.The pore diameters display a clear increase tendency with the increase of template contents.When high Zr incorporation content is used,the template contents have less effect on the pore diameters that almost keep unchanged with the increase of template contents.All the materials possess type IV isotherms with H2 hysteresis loops suggesting the formation of mesophase.The materials with low Zr incorporation content have anatase structures；however,it can not be found in the materials with high Zr incorporation content.TEM images show that some accumulated inter-particulate pores and welldistributed worm-like pores are present in the Zr-incorporated materials.     

铈盐－过硫酸盐复合引发体系的研究

铈盐－过硫酸盐复合引发体系的研究李朝阳，丘坤元（北京大学化学系，北京，１００８７１）关键词复合引发体系，铈盐，过硫酸盐，氧化还原引发本文研究了一种新的复合引发体系，即在传统的单独钟盐引发体系中引人过硫酸盐这一本身具有强氧化性的新组分，提高原体系的引发...     

锰(Ⅲ)离子与羧酸或α-羟基羧酸体系引发丙烯酰胺聚合

锰(Ⅲ)离子可以引发烯类单体自由基聚合。羧酸,α-羟基羧酸对丙烯酰胺聚合有促进作用,其活性顺序为羟基多元羧酸(柠檬酸)>羟基羧酸(乳酸)>羧酸(正丁酸)。测定了在较高酸性([H~+]=3.0M)的硫酸水溶液中,单独Mn~(3+),Nn~(3+)-乙醇酸,Mn~(3+)-乳酸引发丙烯酰胺聚合的活化能与动力学方程。     

有机过氧化物与N,N-二(2-羟烷基)对甲苯胺体系引发烯类聚合及其机理的研究

研究了有机过氧化物BPO,LPO分别与N,N-二(2-羟烷基)对甲苯胺DHET,DHPT组成的体系引发MMA的聚合。测定其聚合速度R_p,聚合表观活化能,聚合速度方程,聚合放热过程的温度与时间的关系。用自旋捕捉和ESR波谱技术,测定了上述体系反应产生的自由基中间体,同时通过聚合物端基分析证实DHET,DHPT组份产生的自由基能引发单体聚合。依据实验结果提出了这类体系的引发机理。     

N-(对甲苯基)马来酰亚胺的自由自聚合与光敏诱导聚合及共聚合

N-(p-methylphenyl) maleimide (PMPMI) was synthesized from the reaction of maleic anhydride with p-methylaniline via two steps processes. Radical polymerization of PMPMI using AIBN as an initiator or initiated with N,N-dimethyl-p-toluidine (DMT) under UV light irradiation have been investigated. Copolymerizations of methyl acrylate (MA), methyl me-thacrylate (MMA) with PMPMI were carried out in THF and cyclohexanone respectively. It was found that the molecular weights of the polymers and copolymers obtained from the cyclo hexanone were always greater than that of from THF. The monomer reactivity ratios were cal-culated.     

4-乙酰氨基-4’-甲基丙烯酰氨基-二苯基甲烷的合成及其聚合

4-Acetamino-4'-methacryloylaminodiphenylmethane (AMDPM) monomer was synthesized from 4,4'-diaminodiphenylmethane via acetylation reaction and then reacted with methacryloyl chloride. AMDPM monomer was characterized by elemental analysis,¹H-NMR and IR spectra. In the presence of 2,2'-azobisisobutyronitrile (AIBN) AMDPM polymerized and formed a brittle homopolymer. The copolymers of methyl acrylate(MA) with AMDPM in various molar ratio were synthesized via free radical polymerization in N,N-dimethylformamide solution.The monomer reactivity ratios were determined by Fineman-Ross method.