带树枝状侧链聚苯乙炔的合成与结构表征

合成了带树枝状聚苯甲醚修饰基团的苯乙炔单体,在Rh[(nbd)Cl2]2催化剂的作用下得到了侧链带聚苯甲醚树枝的新型聚苯乙炔衍生物,用红外吸收光谱、核磁共振谱、紫外可见吸收光谱和凝胶渗透色谱表征了聚合物的结构.发现聚合物的重均分子量达到了57300,在氯仿、N,N-二甲基甲酰胺、四氢呋喃等有机溶剂中有良好的溶解性能.由于侧链上聚苯甲醚树枝体积庞大,聚合物主链采取立构规整的顺-顺式构象,紫外可见吸收光谱在440nm附近出现了显著的共轭主链的吸收肩峰;立构规整的顺-顺式构象使树枝状侧链形成了对主链保护的"夹套效应",聚合物热分解温度从聚苯乙炔母体的225℃提高到295℃.     

ATRP技术制备末端和中间功能化的温度敏感性聚N,N-二乙基丙烯酰胺

合成了2种含有二硫吡啶结构的原子转移自由基聚合(ATRP)引发剂,ATRP引发剂结构采用核磁共振氢谱(1H-NMR)表征.结果显示,二硫吡啶结构被成功引入引发剂结构末端或链中间.利用2种ATRP引发剂分别制备了链末端功能化和链中间功能化的聚N,N-二乙基丙烯酰胺(pDEAAm).采用1H-NMR和凝胶渗透色谱(GPC)对聚合物结构和分子量进行了表征.1H-NMR结果显示,二硫吡啶基团被引入聚合物链末端或中间.GPC结果表明,末端功能化和中间功能化的聚N,N-二乙基丙烯酰胺(pDEAAm)分子量分布指数分别为1.21和1.23,实现了分子量的可控聚合.并且,具有2个引发位点的引发剂引发单体得到聚合物的分子量较大.采用紫外-可见分光光度法研究了聚合物在溶液中的温度响应性.紫外-可见分光光度法结果说明,pDEAAm溶液在28°C发生相分离,在溶液中表现出温度响应性,且最低临界溶解温度(LCST)为28°C.在末端功能化和中间功能化温敏型pDEAAm可用于嵌段共聚物的合成以及与生物大分子的定位结合.特别对于中间功能化的pDEAAm,有望用于星型聚合物和多臂聚合物的设计和制备.     

含偶氮苯侧链分子刷聚合物的合成及其光响应自组装

分子刷聚合物伸展的高分子主链、高密度的侧链和较低的侧链空间缠结,使其展现出独特的流变学、力学性能和特殊的分子聚集状态,在纳米技术、表面科学等领域有着广泛的应用前景.基于同时含有2-羰基溴与炔基基团的大分子试剂聚2-((2-溴代丙酰氧基)甲基)丙烯酸丙炔酯,引发偶氮苯丙烯酸酯单体的原子转移自由基聚合(ATRP)与叠氮功能化的巴比妥酸衍生物的点击反应,合成了新型含偶氮苯侧链的分子刷聚合物聚丙烯酸酯-g-聚(6-(4-丁基-4′-氧偶氮苯)正己基丙烯酸酯)/巴比妥酸(PA-g-PAzo/Bar),研究了其在溶液中的自组装和光响应性行为.随着分子刷聚合物浓度的增加,聚集体由柱状胶束向复合胶束转变.由于光响应性偶氮苯侧链的存在,在紫外光的照射下偶氮苯生色团发生trans-cis异构化转变,促使柱状胶束融合形成多孔网状聚集体,同时球形复合胶束融合形成珍珠项链状聚集体.     

主链含硅的芳族聚酰胺的合成及其气体选择透过性能

采用界面缩合聚合方法，合成了一系列主链含硅的芳族聚酰胺，从化学结构与气体透过性能关系的角度研究了此类聚合物均质膜的气体透过性能，结果表明，此类聚合物膜对Ｈ２、Ｏ２、Ｎ２、ＣＯ２、ＣＨ４的气体透过系数大小顺序符合一般玻璃态聚合物规律；在刚性强的高分子链段中引进柔性基因，可提高聚合物的气体透过系数；高分子主链有较强内旋转能力的聚合物，气体透过系数大；高分子主链的化学结构相同，苯环上带有侧甲基的聚合物有高的气体透过系数；硅原子上带有侧苯基的聚合物，其气体扩散系数大于而溶解系数小于硅原子上携有侧甲基的聚合物．结论为，在刚性高分子主链中引入柔性基团和提高刚性链间隙是增大气体透过含硅聚酰胺膜速率的有利因素．     

含POSS侧基的非环二烯烃易位聚合及离子型杂化聚合物表征

基于七异丁基-胺丙基-多面体低聚倍半硅氧烷(POSS-NH₂)与溴丁烯或溴代十一烯反应, 一步法合成了含POSS侧基的两种杂化二烯烃. 以钌卡宾络合物为催化剂的非环二烯烃易位(ADMET)聚合, 短链二烯烃未能发生, 而长链二烯烃能顺利实现. 将杂化二烯烃转变为离子型杂化二烯烃, 其ADMET聚合活性较高, 随着反应时间延长, 聚合物分子量明显增大, 分子量分布变窄, 体现了逐步聚合的特征. 核磁共振分析揭示了聚合物的不饱和结构和聚合反应的变化过程. 主链不饱和的无定形聚合物, 经氢化作用转变为饱和的离子型杂化聚乙烯, POSS基团精确地连接在聚乙烯骨架的侧位上, 且POSS基团和聚乙烯骨架均表现出较强的结晶能力. 这种离子型杂化聚乙烯具有球形的单分子或聚集形态, 可直接构筑纳米尺度的聚合物材料.     

基于3,5-二氨基苯甲酸(4-烷氧基)苯酯可溶性聚酰亚胺的合成与表征

本文合成了含长烷基侧链的二胺单体3,5-二氨基苯甲酸(4-烷氧基)苯酯,然后使它与2,2-双[4.(3,4-二羧酸基苯氧基)苯基]丙烷二酐在N甲基-2-吡咯烷酮溶液中聚合,再通过化学酰亚胺化得到一系列含有长烷基侧链的聚酰亚胺。聚酰亚胺的结构经红外光谱和核磁共振氢谱确认,并对它的溶解性能、特征粘数、光学性能和热性能等进行了表征。结果表明,所合成的聚酰亚胺具有好的溶解性能、较高的分子量、优异的透光率和较好的热稳定性。     

通过点击化学策略合成双取代功能性聚炔

我们报道利用叠氮基团与乙炔中间体（P2）的侧链端炔的1,3-偶极环加成反应实现双取代聚乙炔的后功能化（P3）的合成路线的设计和实验探索.其中聚乙炔前驱物（P2）由侧链带有三甲基硅乙炔的初级聚乙炔（P1）通过去硅化反应得到.P1由特殊设计的乙炔单体在WCl6-Ph4Sn催化作用下聚合得到.该单体有两个乙炔键,其中之一由三甲基硅封端.本文探索了两种合成路线,即＂两步法＂（目标聚合物P3从初级聚合物P1经由中间体P2得到）与＂一锅法＂（由P1一锅反应直接得到P3,中间体P2未经分离与纯化）.实验结果表明＂一锅法＂更简便,且目标产物P3-1比两步法得到的产物P3-2具有更高的纯度与分子量.聚合反应与聚合物结构通过凝胶色谱（GPC）、傅里叶变换红外光谱（FTIR）与核磁共振氢谱（1HNMR）进行表征.     

含异丙基及三氟甲基可溶性聚酰胺的合成及性能研究

以含异丙基和三氟甲基结构二胺单体3,3′-二异丙基-4,4′-二胺基苯基-4″-三氟甲基甲苯(PATFT)与萘-1,4-二甲酸、间苯二甲酸和4,4-二苯醚二甲酸3种二酸通过膦酰化反应制备一系列新型可溶性聚酰胺,其相对分子量在3.8×104~9.6×104之间.结果表明,该聚合物具有优异的溶解性能,常温不仅能溶解于N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)等高沸点有机溶剂,在加热条件下甚至能较好的溶解在四氢呋喃、氯仿、二氯甲烷等低沸点溶剂中;突出的光学性能,截止波长范围在322~350 nm,80%的透过率波长范围为378~403 nm;良好的热学性能,玻璃化转变温度(Tg)范围在213~220?C,氮气氛围下5%和10%热失重温度范围分别为453~458?C和470~482?C.聚合物薄膜具有优异的机械性能,拉伸强度、杨氏模量、断裂伸长率分别对应为68~97 MPa,1.9~2.9 GPa,14.8%~16.7%.广角X-射线图谱表明聚合物为无定形态结构.     

含有络合功能基的非天然氨基酸的设计、合成及在生物活性肽中的应用

设计合成了一类侧链带有络合基团的非天然氨基酸, 即侧链带有N,N-二羧甲基氨甲基、N,N-二酰胺甲基氨甲基和N,N-二羟乙基氨甲基的苯丙氨酸衍生物, 并将这类非天然氨基酸用于促性腺激素释放激素(LHRH)类似物的固相合成. 高效液相色谱分析结果表明, 粗肽的纯度较好, 易于纯化; 用电喷雾质谱测定了多肽的分子量. 这些非天然氨基酸可作为其它肽类药物合成的构建单元.     

甲基取代的聚芳醚酮酮酰亚胺树脂的合成与性能

N,N′-(4,4′-二苯甲烷)-二偏苯三甲酰亚胺酰氯(DIDC-M)与4,4′-二(2-甲基-苯氧基)三苯二酮(o-Me-DPOTPDK) 进行低温溶液共缩聚,制备了甲基侧基取代的聚芳醚酮酮酰亚胺(o-Me-PEKKI)聚合物.用FT-IR,1H-NMR,DSC,TG 和WAXD对聚合物的结构和性能进行了表征.研究表明:聚合物为非晶态结构;具有较高的玻璃化转变温度(Tg:241 ℃)和较好的耐热性能(Td:487 ℃);能溶解于间甲酚、NMP、氯仿、四氯乙烷等有机溶剂中.     

Disassembly via an environmentally friendly and efficient fluorous phase constructed with dendritic architectures

Traditionally the fluorous phase is generated with perfluorinated alkyl groups that are usually perfluorooctyl or longer and are bioaccummulative and biopersistent and therefore, are considered environmentally unfriendly. Here we report a new concept for the construction of the fluorous phase. This concept is based on the amplification of the fluorous effect with the help of dendritic architectures containing very short semifluorinated groups on their periphery. This new concept was demonstrated by the convergent synthesis of the first and second generation AB₃ and AB₂ benzyl ether dendrons functionalized on their periphery via catalytic nucleophilic addition of their phenolates to perfluoropropyl vinyl ether. The resulting dendrons are liquids. Their fluorous phase affinity was analyzed and demonstrated that the dendritic architecture amplifies the fluorous phase at a specific generation by the number of functional groups on the dendron periphery, and at different generations by increasing their generation number. Therefore, this concept is very efficient for the design and synthesis of new fluorous materials. In addition, by contrast with dendrons containing perfluoroalkyl groups on their periphery, the current dendrons mediate the disassembly of their parent building blocks but do not mediate the self‐assembly in a supramolecular architecture. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2498–2508, 2010     

Synthesis of conjugated dendrons with nonlinear optical activity

New dipolar conjugated dendrons with electron-withdrawing groups on the periphery and electron-donating groups distributed at the core and throughout the dendritic skeleton have been conveniently synthesized. The pi-conjugated dendritic skeleton provides extended conjugation between each electron donor-acceptor pair, resulting in numerous traditional nonlinear optically active chromophores in one single dendron.     

Supramolecular self-organization of "Janus-like" diblock codendrimers: synthesis, thermal behavior, and phase structure modeling

We report on the design and synthesis of three series of segmented amphiphilic block codendrimers, and on their self-organizing behavior in liquid-crystalline mesophases. Connecting two prefunctionalized monodendrons, each differing in their chemical constitution and generation number, yielded these diblock supermolecules. One wedge of the codendrimer was made hydrophobic, and is based on a branched poly(benzyl ether) monodendron functionalized at the periphery by lipophilic aliphatic fragments (also known as Percec dendrons). The other segment was made hydrophilic by the grafting of hydroxyl-containing moieties onto the focal functions of the former dendrons. Both types of dendrons were prepared independently by convergent methods and then joined in the ultimate stage of the synthetic procedure by cross-coupling reactions. In this way, the proportion of the dendritic blocks was varied independently to allow control of the hydrophilic/hydrophobic balance (HHB), the hydrogen-bonding ability, and consequently the capacity to tune the mesomorphic properties of the resulting "superamphiphiles" was anticipated. Essentially all the dendritic compounds display a thermotropic mesomorphism directly at or near room temperature as determined by using X-ray diffraction, polarized optical microscopy, and differential scanning calorimetry. The nature and the supramolecular organization of the mesophases, namely columnar and cubic phases, are correlated to the size of the respective block monodendrons and the chemical structures of the dendromesogens. The molecular organization within the cubic phases can be geometrically described and well understood by the space-filling polyhedron model.     

Codendronized polymers pendent with alternating dendritic wedges

Codendronized polymers pendent with Fréchet‐type poly(benzyl ether) dendron and polyester dendron alternating structure have been produced by combining macromonomer and graft‐from approach. Alternating copolymerization of the styryl dendrons of three generations and N‐(2‐hydroxyethyl)maleimide was used to prepare the polymer backbone bearing the first kind of dendritic wedges, then polyester dendrons were grown up from the pendant hydroxy groups through iterative esterification and deprotection reactions. Then, a kind of codendronized polymer bearing different dendritic wedges with an alternating structure was thus obtained. Since the pendent dendrons were different and each of them was well‐defined, such codendronized polymer can be a multicompartment wormlike molecule. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3994–4001, 2007     

Polyfunctional MDI oligomers through dendrimerization

An accessible pathway to synthesize dendronized MDI oligomers was studied. Two dendrons bearing -CN and -t-butyl functional groups on the periphery were obtained following the synthetic strategy proposed by Newkome et al. Dendrons with one focal point were converted from nitro into amino precursors and used as modifiers in the preparation of new functionalized materials. The coupling reaction of dendrons on oligomers with isocyanate groups was carried out through an easy and quick procedure. The dendronized oligomers showed conformation changes according to the polarity of the solvents, allowing a prediction of a “stimuli-responsive” behavior.     

Designing macromolecules for therapeutic applications: polyester dendrimer-poly(ethylene oxide) "bow-tie" hybrids with tunable molecular weight and architecture

The design and preparation of new polyester dendrimer, poly(ethylene oxide) hybrid systems for drug delivery and related therapeutic applications, are described. These systems consist of two covalently attached polyester dendrons, where one dendron provides multiple functional handles for the attachment of therapeutically active moieties, while the other is used for attachment of solubilizing poly(ethylene oxide) chains. By varying the generation of the dendrons and the mass of the poly(ethylene oxide) chains, the molecular weight, architecture, and drug loading can be readily controlled. The "bow-tie" shaped dendritic scaffold was synthesized using both convergent and divergent methods, with orthogonal protecting groups on the periphery of the two dendrons. Poly(ethylene oxide) was then attached to the periphery of one dendron using an efficient coupling procedure. A small library of eight carriers with molecular weights ranging from about 20 kDa to 160 kDa were prepared and characterized by various techniques, confirming their well-defined structures.     

Dendritic systems based on dinuclear ruthenium or rhodium units generating peripheral catalytic sites

A series of dendritic cations 1-4 containing Ru(2)S(3) or Rh(2)S(3) units, either in the core or in the dendrons, has been synthesized and characterized. The X-ray crystal structure analysis of 2-Cl shows a trigonal bipyramidal Rh(2)S(3) core with propeller-like para-hydroxyphenyl substituents at the sulfur atoms. Reaction of the peripheral OH groups with diphenylphosphino benzoic acid results in the formation of phosphine-functionalized dendritic cations 5-8. The ruthenium-containing cation 5, with three PPh(2) functions at the periphery, acts as ligand for rhodium(I) and enhances significantly the catalytic activity of [[Rh(CO)(2)Cl](2)] for the carbonylation of methanol.     

Geometric disassembly of dendrimers: dendritic amplification

Geometric disassembly of dendritic structures was realized by a cascade cleavage reaction triggered by an initially stimulated group at the dendrimer core. Release of an exponential number of dendrimer fragments was a result of the branching nature of the cleavage pathway. Evidence for the completion of the disassembly process was provided by the absorbance peak of the p-nitrophenoxide ion that was covalently installed at the periphery of the dendrons for this purpose. The release by dendrimer disassembly of an exponential number of dendrimer fragments that serve to alter the properties of a system is termed dendritic amplification.     

Synthesis and energy-transfer properties of poly(amidoamine) dendrons modified with naphthyl and dansyl groups

Poly(amidoamine) dendrons of 1-3 generations with naphthyl groups at the periphery and a dansyl group at the focal point were synthesized and carefully characterized. Intramolecular energy-transfer properties of these flexible aliphatic-scaffold light-harvesting dendrons were investigated by UV-vis absorption and fluorescence spectroscopy. Efficient energy transfer from the naphthyl groups to the dansyl group occurred for both the first and the second generation dendrons (the energy-transfer efficiency was 94.3% and 76.9%, respectively), whereas the third generation dendron exhibited a low energy-transfer efficiency of 17.8%. The average donor-acceptor distances between the naphthyl and dansyl groups were calculated for different generation dendrons. Different degrees of the backfolding of dendritic branches were used to interpret the different donor-acceptor distances.     

Synthesis and self-assembly of supramolecular dendritic "Bow-Ties": effect of peripheral functionality on association constants

Self-assembled polyester dendritic bow-ties with various peripheral groups were prepared, and their association constants were measured by (1)H NMR in CDCl(3). The two complementary dendrons were prepared by attachment of either a bis(adamantylurea) or a glycinylurea to the focal point of the dendron. The parent self-assembled system with benzylidene acetals on one periphery and isopropylidene acetals on the other had an association constant of 520 M(-)(1). Upon deprotection of one dendron, the association constant is increased by more than an order of magnitude as the solubility of the hydroxyl-terminated dendron in CDCl(3) is decreased. In contrast, attachment of tri(ethylene oxide) units to the periphery of one dendron lowers the association constant by almost an order of magnitude. The causes of these relatively large changes in complex strength are discussed in terms of solubility, steric effects, competitive hydrogen bonding, and the structure of the dendritic scaffold.