Using the mixture of cationic surfactant cetyltrimethylammonium bromide(CTAB) and six nonionic surfactants as templates, meso porous silica was synthesized. The d space of silica templated by CTAB is 3.5 nm. The d spaces could be controlled by changing the ratio of nonionic to cationic surfactants and by increasing the length of nonpolar chain of nonionic surfactants in the mixed cationic nonionic surfactant templating systems. The pore dimension of silica in the mixed surfactants templating system is larger than that in CTAB system and a well ordered structure of pore array was maintained. [WT5HZ]
A mesogen-jacketed liquid crystal polymer,poly{2,5 -bis［(4′-hexyloxyphenyl)oxycarbonyl］styrene}(PHPCS),with number-average d molecular weight of 1.28×１０5 and polydispersity of 1.48 was prepared vi a 2,2,6,6 -tetramethyl-piperidinyloxy mediated free radical polymerization.The thermotr opic behavior was studied by a combination of differential scanning calorimetry, thermogravimetry,polarized optical microscope and wide-angle X-ray diffracti on.PHPCS was not crystalline over the entire temperature region studied.On hea ting,PHPCS first became an isotropic melt at glass transition temperature (T g) and then a mesophase at temperatures much higher than T g.On subseq uent cooling,the formed ordered phase disappeared above T g.Contrary to t heoretical predictions and previous experimental observations,the transition fr om isotropic melt to liquid crystalline phase was an endothermic process and th e order-disorder transition took place with concurrence of heat release.
High-quality mesoporous silica MCM-48 were synthesized under basic conditions by using the mixture of cetyltrimethylammonium bromide (CTAB) and alkylamine (CnNH2n+3 n=8,10,12,14, respectively) as templates. The effects of the alkylamines with different chain lengths (n=8,10,12,14,16,18, respectively) on the silica structure were investigated.
The treatment of tetrakis (4-pyridyl) porphyrin H2TPyP with a hydrated rare earth (III) acetylacetonate RE(acac)3 · nH2O (RE=Y, Eu, Gd) in 1,2, 4-trichlorobenzene (TCB) pro- duced a monomeric porphyrinato rare earth compound RE (TPyP) acac, which further reacted with dicyanobenzene in amyl alcohol in the presence of 1, 8-diazabicyclo [5. 4. 0] undec-7-ene (DBU), giving HRE(TPyP) (Pc) in a good yield. Upon exposure to air, part of the protonated mixed double-deckers in CHC13 solutions converted slowly to the corresponding neutral complexes RE (TPyP) (Pc). These protonated complexes were characterized by means of UV-V is, IR, NMR, mass spectroscopies. The quaternarization of these protonated mixed double-deckers with methyl iodide produced the salts of tetramethylated cations [HRE(TMPyP) (Pc)]4+.
JIANG Jian-zhuang,LIU Wei ,SUN Xuan ,ZHANG Xian-xi and NG Dennis K. P. (Key Laboratory for Colloid and Inter face Chemistry of the Educational Ministry, Department of Chemistry, Shandong University, Jinan 250100, P. R. China
A novel blue light-emitting coil-rod-coil triblock oligomer, PEO-PHP-PEO, which consists of para-hexaphenyl (PHP) as the rigid rod and poly(ethylene oxide) (PEO, M w = 750) as the flexible coil, has been synthesized. It is the first soluble poly(para-phenylene) molecule containing no lateral substituent, which can dissolve not only in organic solvents such as chloroform and THF, but also in water. The critical micelle concentration (CMC) of PEO-PHP-PEO in water is 5.25×10-4 mol·L-1 and the surface tension at CMC, 鉉MC, is 61.29 mN·m-1. The absorption peak of the molecularly dissolved PEO-PHP-PEO in water is centered at 323 nm and the fluorescence spectrum has a maximum at 432 nm and shows the vibronic fine structure typical of molecular dissolution. The photoluminescence spectrum of the aggregate solution is similar to that of the PHP polycrystal film, indicating that the ordered packing of PHP block has taken place due to a combination of hydrophobic interaction and p-p stacking. The oligomer self-assembles into cotton-like nanofibers with diameter of about 20 nm in 5.0×10-3 mol·L-1 aqueous solution.
HE Haifeng, CAO Hongqing, WAN Xinhua, TU Yingfeng, CHEN Xiaofang & ZHOU Qifeng Department of Polymer Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China Correspondence should be addressed to Wan Xinhua (e-mail: xhwan@pku.edu.cn)
Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by ~1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl_2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization ofmenthyl methacrylate (MnMA) in chlorobenzene, which yielded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.
