PHOTOLUMINESCENT PROPERTIES OF OCTADECYLRHODAMINE B IN WATER, IN ALCOHOLS AND IN MIXED WATER-ALCOHOL SOLUTIONS

Abstract Fluorescence, excitation and absorption spectra of octadecylrhodamine B (ORB) have been observed in solutions of water, methanol, ethanol and other simple alcohols. A remarkable increase in the ORB fluorescence intensity occurs when the probe is transferred from water to the alcohols. This effect is ascribed to the release of ORB fluorescent monomers from nonfluorescent multimers, which exist predominantly in water. The dependence of the fluorescence intensity on the composition of water-alcohol binary solvent systems shows that hydrophobic interactions play an important role in the monomer = multimer equilibrium of ORB in these solutions. The fluorescence lifetimes of ORB in the alcohols are also reported.     

聚苯乙烯-b-聚硅氧烷-b-聚苯乙烯三嵌段共聚物的合成及表征

采用乙烯基封端的聚 (二甲基硅氧烷 )与溴化氢反应制得末端含有C Br的双官能聚 (二甲基硅氧烷 ) ,以此聚 (二甲基硅氧烷 )大分子为引发剂 ,CuCl为催化剂 ,4 ,4′ 二 (5 壬基 ) 2 ,2′ 联吡啶为配体 ,通过原子转移自由基聚合法 ,制得分子量和结构可控的聚苯乙烯 b 聚硅氧烷 b 聚苯乙烯 (PSt b PDMS b PSt)共聚物 .     

PLA-b-PEO-b-PLA三嵌段共聚物分子聚集体性质的研究

采用开环聚合的方法 ,合成了组成不同的PLA b PEO b PLA三嵌段共聚物 .滴加选择性溶剂水于共聚物的良溶剂溶液中 ,制备了共聚物以水为介质的“平头”聚集体胶束溶液 .把聚集体胶束溶液浇铸在云母片上 ,采用扫描探针显微镜 (SPM)表征了其形貌和表面微粘弹性 .发现脱离了极性介质水的聚集体的表面性质发生了不均一化 ,聚集体的顶部比相连接的部分具有较高的储能模量 .聚集体环境的改变使聚集体中不同嵌段的迁移导致了这种表面粘弹性的不均一 .另外 ,采用动态光散射的方法测量了体系溶液中聚集体胶束的尺寸 .实验发现光散射所得到的聚集体的尺寸远远大于SPM所得到尺寸 .增加聚合物的起始浓度使聚集体胶束的尺寸以及多分散性都在不同程度上增大 .然而聚合物的不同 ,这种增加的程度会有比较大的差别     

ABA三嵌段离子型共聚物的合成及溶液自组装

以对二溴苄作引发剂,引发苯乙烯和甲基丙烯酸对硝基苯酚酯(NPMA)相继进行原子转移自由基聚合(ATRP),合成了3个三嵌段聚合物PNPMA-b-PS-b-PNPMA,其中聚苯乙烯段含有146个单元,PNPMA段的结构单元数分别为8、20和36.对这3个三嵌段共聚物分别进行水解反应及与2-氨基吡啶的取代反应,得到了具有相反电荷的PMAA-b-PS-b-PMAA和PNPMAAm-b-PS-b-PNPMAAm两种6个三嵌段共聚物.用核磁、红外和GPC表征了聚合物的结构、分子量及分子量分布等.将这两种三嵌段共聚物以等摩尔混合,在水中可自组装成碗形聚集体结构,讨论了可能的形成机理.     

PREPARATION AND PROPERTIES OF CHLOROPHYLL/WATER-SOLUBLE MACROMOLECULAR COMPLEXES IN WATER. STABILIZATION OF CHLOROPHYLL AGGREGATES IN THE WATER-SOLUBLE MACROMOLECULE

Abstract— As an artificial model compound of the chlorophyll-protein complex in vivo , the chlorophyll/water-soluble macromolecular complexes were prepared by using synthetic linear polymers of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), and a natural polymer of bovine serum albumin (BSA). By the method described here, it is possible to prepare an aqueous chlorophyll (Chl)-macromolecular complex solution of a desired Chi aggregate, such as: Chi a (670), Chi a (740) and Chi b ; and with a desired relative content and concentration. These procedures for preparing such complexes will have wide applicability for technical use in Chi studies. For example, extremely diluted aqueous complex solutions of at least 1 × 10^-4% wt Chi a (670 or 740)-macromolecular complex / wt can be obtained without changing the spectral features. From viscosity measurements, the structures of the complexes were inferred: (1) for a linear macromolecular (PVA or PVP) complex, a Chi species is tightly surrounded by a chain of the polymer causing shrinkage of the chain; (2) globular BSA molecules surround Chi species to form a large complex. The mechanism of stabilization of Chi aggregates in thylakoid membrane was discussed concerning an analogy to the complexes studied here.     

B段选择性成膜溶剂对 ABC 型氟化三嵌段共聚物氟化组分表面富集行为的影响

利用ATRP技术合成聚甲基丙烯酸甲酯-b-聚甲基丙烯酸丁酯(或聚甲基丙烯酸十八烷基酯)-b-聚(甲基丙烯酸2-全氟辛基乙酯)(PMMA230-b-PBMA12(或PODMA12)-b-PFMAn)嵌段共聚物.通过X射线光电子能谱(XPS)、X射线衍射(XRD)、动态光散射(DLS)等技术研究了中间段选择性成膜溶剂对氟化...     

聚丙烯-聚乙烯嵌段共聚物的分子结构及性能的研究

本工作用核磁共振(~(13)C-NMR)、示差扫描量热(DSC)、动态力学分析(DMA)和扫描电子显微镜(SEM)等技术研究了将丙烯、乙烯单体两步分段共聚、预期为聚丙烯-聚乙烯嵌段共聚物的合成物(简称为聚丙烯-聚乙烯嵌段共聚物或嵌段共聚物)。结果表明,在嵌段共聚物中含有一定量的、能为正庚烷抽提出来的乙丙无规共聚物(EPR);分段共聚的产物并非预想的PP-b-PE两嵌段共聚物,而是含有多种组分的共混物;形态表征的结果表明了嵌段共聚物为多相体系,EPR和PE形成分散相以球形无规分布于PP基体中。     

芴-苯并噻二唑-苯胺类共聚物的合成与发光性能

用Suzuki缩聚反应分别将窄带隙单元-苯并噻二唑-二苯胺(DPABT)和苯并噻二唑-三苯胺(TPABT)引入聚芴主链,合成了共聚物PF-DPABT和PF-TPABT,并比较了共聚物的发光性能.随着窄带隙单元含量的增加,其特征发射逐渐增强,说明发生了从聚合物主体单元到窄带隙单元有效的能量转移.两种共聚物在低窄带隙单元含量(1mol%)下的电致发光光谱仅出现窄带隙单元的特征发射,PF-DPABT共聚物为650～680nm之间的饱和红光,而PF-TPABT共聚物为590～610nm之间的橙红光,聚芴主体单元的发射被完全淬灭,说明与光致发光过程相比,电致发光过程中的能量转移更完全.基于共聚物PF-DPABT-1及PF-TPABT-5器件的最大外量子效率分别为1.3%和2.0%,器件结构为ITO/PEDOT:PSS/polymer/Ba/Al,是一类有希望的红光材料.     

苯乙烯-丁二烯-苯乙烯三嵌段共聚物新型加氢催化剂的研究

烯烃加氢得到烷烃,从化学热力学角度判断这个反应可以进行,由于氢分子相当稳定,ＨＨ键不易受极化的影响而断裂,实际上,如果没有催化剂的存在,反应是很难进行的．各种过渡金属,例如铂、钯、铑、钴、铱和镍等都具有未充满和不稳定的ｄ电子轨道,容易吸附大量的氢并使其活化,从而很容易对许多基团进行氢化反应．钌／二烯烃／氢气反应体系就符合上述原理,苯乙烯丁二烯苯乙烯三嵌段共聚物（ＳＢＳ）就属二烯烃类共聚物,由于这类共聚物中存在ＣＣ不饱和双键,在日光、紫外光、热等环境下,其耐侯性和热稳定性不好,限制了它在更广泛…     

SYNTHESIS OF TRIBLOCK COPOLYMERS OF STYRENE AND ISOPRENE BY A NITROXIDE-MEDIATED LIVING FREE RADICAL POLYMERIZATION

The controlled free radical polymerization of styrene and isoprene initiated with benzoyl peroxide (BPO) in the presence of 2,2,6,6-tetramethyl piperidine-N-oxyl (TEMPO) at 125 ℃ were performed. The obtained polyisoprene and polystyrene homopolymers served as macroinitiators for block copolymerization of isoprene and styrene to synthesize poly(styrene-b-isoprene) and poly(isoprene-b-styrene) diblock copolymers. Diblock copolymers with well-defined structures as well as controlled and narrow molecular weight distribution wereobtained from the lower-mass polystyrene and polyisoprene homopolymers. These copolymers were found to be active as macroinitiators in the synthesis of the poly(styrene-b-isoprene-b-styrene) and poly(isoprene-b-styrene-b-isoprene) triblock copolymers. 1H-NMR spectroscopy and gel permeation chromatography (GPC) were used for the investigation of polymer strucmre, molecular weight and polydispersity (PD).     

共聚物组成对线形苯乙烯-丁二烯-苯乙烯嵌段共聚物粘弹弛豫与相形态的影响

研究了不同组成的苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)的相形态与粘弹弛豫.用透射电子显微镜(TEM)表征了SBS的形态,结果显示,几种SBS均呈层状结构,随着苯乙烯含量的降低,聚苯乙烯(PS)相的尺寸稍有减小,而聚丁二烯(PB)相尺寸明显增大.用动态流变学方法考察了不同温度下SBS嵌段大分子的弛豫行为,结果表明,苯乙烯含量减少,PS相玻璃化转变和有序-无序转变温度均降低;苯乙烯含量少的,在有序-无序转变过程中呈现出高且宽的损耗峰,表明有序-无序转变过程中能量的耗散主要由两相溶合时分子链间的内摩擦所决定,分子链越长,内摩擦越大,能量耗散越大.     

PNIPAM-b-聚碳酸酯温敏胶束的制备及用作药物控制释放载体的研究

以多孔硅球固定化猪胰脂肪酶(IPPL)为催化剂,温敏性HO-PNIPAM为大分子引发剂,5-甲基-5-烯丙氧羰基-三亚甲基碳酸酯(MAC)和5,5-二甲基三亚甲基碳酸酯(DTC)为共聚单体,通过开环聚合合成了不同结构比例的两亲性嵌段型共聚物P(MAC-co-DTC) -b-PNIPAM.该嵌段型共聚物在水中可自组装形成...     

苯乙烯－乙烯共聚物的合成及其结构性能的研究

用负载型钛系催化剂ＭｇＣｌ_２／ＴｉＣｌ_４，ＮｄＣｌ_３／ＡｌＥｔ_３（ＳＮ－１催化剂）制备出组份比例变化的苯乙烯－乙烯共聚产物．共聚产物通过溶剂萃取分离、~１３Ｃ－ＮＭＲ、ＩＲ、动态粘弹谱进行表征，并初步进行了与聚苯乙烯（ａＰＳ）共混作用的研究．结果表明，ＳＮ－１催化剂能有效地催化苯乙烯与乙烯共聚合．共聚产物为含有均聚聚苯乙烯的共聚物复合物，其中的２５ｍｏｌ％的苯乙烯参加了共聚．共聚产物与ａＰＳ共混可明显提高ａＰＳ的冲击强度和断裂伸长率．     

SYNTHESIS AND CHARACTERIZATION OF WATER-SOLUBLE BLOCK COPOLYMERS WITH AN END-TAGGED NAPHTHALENE PROBE

Water-soluble A-B block copolymers of 2-perfluoroethyl-2-oxazoline or 2-pentyl-2-oxazoline as hydrophobic monomers and 2-methyl-2-oxazoline as hydrophilic monomer were prepared by means of the living cationic ring-opening polymerization. The polymerization was initiated with N-methyl-2-(1-naphthyl)-2-oxazolinium trifluoromethanesulfonate as fluorescence label followed by sequential addition of the hydrophobic and the hydrophilic monomer. The polymerization was monitored by ¹H NMR spectroscopy and gel permeation chromatography (GPC) measurements. The results revealed that fluorophilic block copolymers can be prepared by this method while lipohilic block copolymers are not accessible by this monomer sequence. Micelle formation of the fluorophilic block copolymers in aqueous solution was studied by means of steady-state fluorescence spectroscopy which confirmed strong intermolecular excimer formation of the terminal bounded naphthalene moiety. In chloroform as a good solvent for both blocks, only monomer fluorescence could be observed.     

疏水链段对两亲性三嵌段共聚物在水中聚集行为的影响

以结构明确的两端为短的聚苯乙烯(PS)或聚甲基丙烯酸甲酯(PMMA)链段,中间为长的聚乙二醇(PEG)链段的PS-b-PEG-b-PS和PMMA-b-PEG-b-PMMA两亲性三嵌段共聚物为对象,研究了PS和PMMA链段对其在水中形成胶束和凝胶的影响.两种三嵌段共聚物在水中形成以PS或PMMA链段为核、PEG链段为壳的球形胶束,流体力学半径Rh,app为15.3~24.3 nm,并随PEG链段长度增长而增大.临界胶束浓度CMC均小于0.01 mg/mL,随着PS和PMMA链段长度的增加而减小.PS-b-PEG-b-PS浓度高于4.5 wt%可形成较强的疏水缔合的物理凝胶,平衡模量Ge可达到103Pa;PMMA-b-PEG-b-PMMA浓度高于7.5 wt%可以形成弱的凝胶,Ge<10 Pa.凝胶的储存模量G′和损耗模量G″均随着PS或PMMA链段的增长而增大.     

苯乙烯－乙烯共聚物的合成及其结构性能的研究

用负载型钛系催化剂ＭｇＣｌ２／ＴｉＣｌ４，ＮｄＣｌ３／ＡｌＥｔ３（ＳＮ－１催化剂）制备出组份比例变化的苯乙烯－乙烯共聚产物，共聚产物通过溶剂萃取分离，＾１３Ｃ－ＮＭＲ，ＩＲ，动态粘弹谱进行表征，并初步进行了与聚苯乙烯共混作用的研究。结果表明，ＳＮ－１催化剂能有效地催化苯乙烯与乙烯共聚合，共聚产物为含有均聚聚苯乙烯的共聚复合物，其中约２５ｍｏｌ％的苯乙烯参加了共聚。共聚产物与ａＰＳ共混可明显提高ａＰ     

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 ,…     

RADICAL GRAFTING REACTIONS ONTO STARCH AND OTHER WATER-SOLUBLE COPOLYMERS IN ISOLATED GEL DROPLETS

A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH_4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using aceric sulphate redox initiator, and their properties compared. The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions. The effects of the ratios of [backbone]/[graft monomer], [ AM]/[ AA]/[AMPS] , [Ce~(4+)]/[ S_2O_8=] and pH value on the reaction rate , conversion, grafting degree, grafted chain length and the product molecular weight have been investigated.     

FOAMABILITY OF PEO-PPO-PEO TRIBLOCK COPOLYMERS (P85 AND F108) AND ROLE OF THE FOAM FILMS

The foamability of two commercial PEO-PPO-PEO triblock copolymers (Synperonic P85 and F108, ICI) was studied and compared to the properties of single foam films. The volume of a steady-state foam column created with a combined pneumatic-mechanical device is used as a measure of the copolymers foamability. Experiments were carried out at bulk copolymer concentrations corresponding to full surface coverage, i.e. constant area per molecule, under equilibrium conditions. The foamability of F108 solutions was higher than that of P85 although the surface activity of both copolymers was similar. The foam volume increases with increasing the bulk copolymer concentration. Higher electrolyte concentration or lower pH caused the foam volume to diminish. A pronounced parallelism between the properties of dynamic foams and single microscopic foam films was observed: when thicker single foam films were formed (from F108 solutions) the steady