Synthesis of novel blue‐light‐emitting polypyridine

A new regioregular head‐to‐tail (HT)‐type polypyridine with methoxyethoxyethoxy (MEEO) side chains, HT‐PMEEOPy, was synthesized by means of Kumada‐Tamao coupling polymerization of a Grignard monomer with a Ni catalyst. Although the polymer was precipitated in THF during polymerization, multiangle laser light scattering (MALLS) analysis indicated that the weight‐average molecular weight (M_w) was about 25,000. The HT content in the polymer was 95%. A solution of HT‐PMEEOPy in CHCl₃ was found to emit a strong blue light when the solution was irradiated with UV light; the UV‐vis absorption maximum (λ_max) and photoluminescence maximum (λ_{max em}) were at 392 and 460 nm, respectively. To clarify the effect of regioregularity of PMEEOPy on the photoluminescence, head‐to‐head (HH) PMEEOPy was synthesized by means of Yamamoto coupling polymerization. The photoluminescence of HH‐PMEEOPy (λ_max = 330 nm, λ_{max em} = 414 nm) was weaker than that of HT‐PMEEOPy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and Self-Association of Stimuli-Responsive Diblock Copolymers by Living Cationic Polymerization

The living cationic polymerization of several functional monomers in the presence of an added base is investigated as a possible preparation of a new series of water-soluble or stimuli-responsive copolymers. Under appropriate conditions, the polymerization allows the selective preparation of polymers with various shapes and different sequence distributions of monomer units, including stimuli-responsive block copolymers, gradient copolymers, poly(vinyl alcohol) graft copolymers, and star-shaped polymers. The stimuli-induced self-association of the diblock copolymers is also examined. An aqueous solution of the diblock copolymer with a thermo-sensitive segment undergoes rapid physical gelation upon warming to the critical temperature to give a transparent gel, and returns sensitively to the solution state upon cooling. The sharp transition of stimuli-responsive segments with highly controlled primary structure turns out to play an important role in the self-association. Small-angle neutron scattering, dynamic light scattering, and electron microscopy studies reveal that the physical gelation involves a thermosensitive micellization of diblock copolymers (core size: 18-20 nm) and subsequent micelle macrolattice formation (bcc symmetry). Based on the gelation mechanism, several stimuli-responsive gelation systems are achieved using other stimuli such as the addition of a selective solvent or compound, cooling, pH change, and irradiation with ultraviolet light.     

Thermo-Responsive MOF/Polymer Composites for Temperature-Mediated Water Capture and Release

We report an in situ polymerization strategy to incorporate a thermo-responsive polymer, poly(N-isopropylacrylamide) (PNIPAM), with controlled loadings into the cavity of a mesoporous metal–organic framework (MOF), MIL-101(Cr). The resulting MOF/polymer composites exhibit an unprecedented temperature-triggered water capture and release behavior originating from the thermo-responsive phase transition of the PNIPAM component. This result sheds light on the development of stimuli-responsive porous adsorbent materials for water capture and heat transfer applications under relatively mild operating conditions.     

Synthesis of Stimuli-responsive Nanoparticles by Solution Polymerization

In this study, stimuli-responsive nanoparticles were prepared by solution polymerization. Two synthesis routes are proposed to synthesize the particles, the monomer route and the polymer/monomer route. For the monomer route, pH and thermal sensitive nanoparticles were synthesized from acrylic acid and N-isopropylacrylamide. For the polymer/monomer route, the pH sensitive nanoparticles were synthesized from chitosan and acrylic acid. The effect of reaction time, initiator concentration and agitation rate on the particle size and the size distribution were investigated. The stimuli-responsive nanoparticles could be directly blended with other polymers to prepare stimuli-responsive functional membranes.     

Polymer nanostructure development of fluorinated and aliphatic monoacrylates in smectic liquid crystals via photopolymerization

To develop viable polymer stabilized liquid crystal systems, it is crucial to understand the factors that affect polymer nanostructure evolution. This work examines the influence of the photopolymerization of aliphatic and fluorinated monoacrylate monomer within a room temperature smectic liquid crystal (LC). Additionally, the effect of LC order on polymerization kinetics, monomer and polymer organization, and the effect of the polymer on LC properties have been examined. Through this work, insight has been gained regarding the impact that the introduction of a fluorinated monoacrylate monomer has on polymerization kinetics, LC organization, and monomer/polymer segregation and organization within a polymer/LC system. Fluorinated moieties lower the surface energy of the monomer to enhance segregation between the smectic layers of the LC as compared with an analogous aliphatic monomer. Additionally, the enhanced segregation significantly increases the polymerization rate in the smectic phase and drives the continued segregation of the fluorinated polymer during and after polymerization. Fluorination also leads to the formation of an ordered polymer nanostructure if polymerized in ordered LC phases. This ordering is particularly evident when the fluorinated monomer is polymerized in the smectic phase in which the monomer is organized between the smectic layers of the LC. In addition, the ordered polymer structure found with the fluorinated monomer in the smectic phase leads to continued birefringence above the clearing point of the LC due to surface interactions between the LC and the ordered fluorinated polymer. The continued birefringence offers an exceptional opportunity to examine how factors such as polymer molecular mass and UV light intensity affect the overall polymer morphology of these polymer/LC systems. As the initiator concentration and UV light intensity are decreased, longer polymer chains form lattice-type morphologies; whereas, shorter polymer chains form smoother morphologies that more closely mirror the texture of the LC smectic phase.     

Polymer nanostructure development of fluorinated and aliphatic monoacrylates in smectic liquid crystals via photopolymerization

To develop viable polymer stabilized liquid crystal systems, it is crucial to understand the factors that affect polymer nanostructure evolution. This work examines the influence of the photopolymerization of aliphatic and fluorinated monoacrylate monomer within a room temperature smectic liquid crystal (LC). Additionally, the effect of LC order on polymerization kinetics, monomer and polymer organization, and the effect of the polymer on LC properties have been examined. Through this work, insight has been gained regarding the impact that the introduction of a fluorinated monoacrylate monomer has on polymerization kinetics, LC organization, and monomer/polymer segregation and organization within a polymer/LC system. Fluorinated moieties lower the surface energy of the monomer to enhance segregation between the smectic layers of the LC as compared with an analogous aliphatic monomer. Additionally, the enhanced segregation significantly increases the polymerization rate in the smectic phase and drives the continued segregation of the fluorinated polymer during and after polymerization. Fluorination also leads to the formation of an ordered polymer nanostructure if polymerized in ordered LC phases. This ordering is particularly evident when the fluorinated monomer is polymerized in the smectic phase in which the monomer is organized between the smectic layers of the LC. In addition, the ordered polymer structure found with the fluorinated monomer in the smectic phase leads to continued birefringence above the clearing point of the LC due to surface interactions between the LC and the ordered fluorinated polymer. The continued birefringence offers an exceptional opportunity to examine how factors such as polymer molecular mass and UV light intensity affect the overall polymer morphology of these polymer/LC systems. As the initiator concentration and UV light intensity are decreased, longer polymer chains form lattice-type morphologies; whereas, shorter polymer chains form smoother morphologies that more closely mirror the texture of the LC smectic phase.     

多孔二氧化钛薄膜涂层的制备和双亲性质研究

二氧化钛因其具有光催化等性能而备受关注 [1] .其薄膜材料在紫外光的照射下 ,能产生活泼自由基 ,自由基能分解有机化合物 ,具有杀菌和自清洁作用 ;同时在紫外光照射时也能诱导材料产生超双亲特性 (油或水在其表面的接触角为 0°) ,赋予材料许多重要的应用 [2～ 4 ] .但二氧化钛薄膜材料表面的超双亲特性在停止紫外光照射后逐渐变弱 ,接触角也随放置时间的增加而增加 [5] .因此需要制备一种不需紫外光照射就具有永久双亲性能的薄膜涂层 .近期的研究表明 ,一些具有孔结构的薄膜涂层具有永久的双亲性能 ,该性能是由涂层本身的多孔性和平均孔尺…     

具有聚集诱导发光效应的咔唑基三苯乙烯衍生物单体及聚合物

合成了一类新的咔唑基三苯乙烯衍生物单体及其聚合物.利用示差扫描量热法(DSC)、热重分析法(TGA)、紫外可见分光光度法和荧光分光光度法等对单体和聚合物的性能进行了初步的表征.实验结果表明,该单体和聚合物具有较高的玻璃化转变温度(Tg),分别为210℃和229℃;单体和聚合物均具有很高的热稳定性,热失重5%的温度分别为466℃和467℃;单体具有明显的聚集诱导发光性能(AIE),而聚合物则具有聚集诱导增强发光性能(AIEE);所合成的单体和聚合物有望在OLED器件以及化学传感器上得到应用.     

POLYBINAPHTHYLS INCORPORATING (R)-20,''-BINAPHTHO-20-CROWN-6AND NAPHTHYL MOITIES

Chiral polymer was synthesized by the polymerization of (R)-6,6'-bistributylstannyl-2,2'-binaphtho-20-crown-6(M-1) with 1,4-dibromo-2,3-bisbutoxy-naphthyl (M-2) by Pd(PPh3)4 catalyzed Stille coupling reaction. Both monomer and polymer were analyzed by NMR, MS, FT-IR, UV, polarimetry, DSC-TGA, CD, fluorescent spectroscopy and GPC. The major difference between monomer and polymer is that a long wavelength Cotton Effect was observed for the polymer due to its more extended conjugation in the repeating unit and a highly rigid backbone in the polymer chain. Polymer has strong blue fluorescence due to the efficient energy migration from the extended π-electronic structure of the repeating unit of the polymer to the chiral binaphthyl core and is expected to have potential application in the materials of fluorescent sensors and chiral chromatographic packing for resolution ofracemic amino acid.     

POLYBINAPHTHYLS INCORPORATING (R)-2,2''''-BINAPHTHO-20-CROWN-6 AND NAPHTHYL MOITIES

Chiral polymer was synthesized by the polymerization of (R)-6,6'-bistributylstannyl-2,2'-binaphtho-20-crown-6 (M-1) with 1,4-dibromo-2,3-bisbutoxy-naphthyl (M-2) by Pd(PPh3)4 catalyzed Stille coupling reaction. Both monomer and polymer were analyzed by NMR, MS, FT-IR, UV, polarimetry, DSC-TGA, CD, fluorescent spectroscopy and GPC. The major difference between monomer and polymer is that a long wavelength Cotton Effect was observed for the polymer due to its more extended conjugation in the repeating unit and a highly rigid backbone in the polymer chain. Polymer has strong blue fluorescence due to the efficient energy migration from the extended n-electronic structure of the repeating unit of the polymer to the chiral binaphthyl core and is expected to have potential application in the materials of fluorescent sensors and chiral chromatographic packing for resolution of racemic amino acid.     

Size control of phase‐separated liquid crystal droplets in a polymer matrix based on the phase diagram

When a mixture of liquid crystal (LC) and photo reactive monomer is irradiated by UV light, polymerization occurs and LC droplets form through phase separation, producing polymer dispersed LCs (PDLCs). Although size control of LC droplets and reduced amounts of LC in PDLC films are important in applications, precise size control of LC droplets at a low LC fraction has not yet been accomplished. In this study, the phase diagrams of the LC/initial monomer and the LC/polymer during polymerization were used to control LC droplet size at various LC fractions. Both the relative position of the sample in the initial phase diagram and the shift of the phase separation line during polymerization were shown to be important in determining the size of LC droplets. Our results are expected to provide a new strategy for precise size control of LC droplets especially at a low LC fraction range, which would be a great help for PDLC applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Photoinduced cationic ring‐opening frontal polymerizations of oxetanes and oxiranes

The photoinitiated cationic ring‐opening polymerizations of certain epoxides and 3,3‐disubstituted oxetanes display the characteristics of frontal polymerizations. When irradiated with UV light, these monomers display a marked induction period, during which little conversion of the monomer to the polymer takes place. The local application of heat to an irradiated monomer sample results in polymerization that occurs as a front propagating rapidly throughout the entire reaction mass. For the characterization of these frontal polymerizations, the use of a new monitoring technique, employing optical pyrometry, has been instituted. This method provides a simple, rapid means of following these fast polymerizations and quantitatively determining their frontal velocities. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1630–1646, 2004     

智能蜂窝状有序多孔薄膜：体系构建、响应性能及应用探索

蜂窝状有序多孔膜是一种典型的具有微、纳米尺寸的图案化高分子薄膜材料,在超疏水表面、光电材料、组织工程、生物医学、传感器等领域都具有良好的应用前景。表面形貌或性质具有可逆刺激响应特性的智能型多孔膜不仅拥有常规多孔膜的性能,而且还拥有独特的"开-关"功能,因此受到广泛关注。本文回顾了智能有序多孔膜近年的研究进展,重点对其体系构建、响应方式、机理、性能和相关应用进行了归纳与分析,评述了不同刺激响应多孔膜的特点及优劣势,探讨了智能多孔膜的优化设计及提高响应性能等问题,指出了目前面临的挑战,并展望了未来的发展方向。     

Guest-to-host transmission of structural changes for stimuli-responsive adsorption property

We show that structural changes of a guest molecule can trigger structural transformations of a crystalline host framework. Azobenzene was introduced into a flexible porous coordination polymer (PCP), and cis/trans isomerizations of the guest azobenzene by light or heat successfully induced structural transformations of the host PCP in a reversible fashion. This guest-to-host structural transmission resulted in drastic changes in the gas adsorption property of the host-guest composite, displaying a new strategy for creating stimuli-responsive porous materials.     

POLYBINAPHTHYLS INCORPORATING (R)-2,2’-BINAPHTHO-20-CROWN-6 AND NAPHTHYL MOITIES

Chiral polymer was synthesized by the polymerization of （R）-6,6＇-bistributylstannyl-2,2＇-binaphtho-20-crown-6 （M-1） with 1,4-dibromo-2,3-bisbutoxy-naphthyl （M-2） by Pd（PPhs）4 catalyzed Stille coupling reaction. Both monomer and polymer were analyzed by NMR, MS, FT-IR, UV, polarimetry, DSC-TGA, CD, fluorescent spectroscopy and GPC. The major difference between monomer and polymer is that a long wavelength Cotton Effect was observed for the polymer due to its more extended conjugation in the repeating unit and a highly rigid backbone in the polymer chain. Polymer has strong blue fluorescence due to the efficient energy migration from the extended n-electronic structure of the repeating unit of the polymer to the chiral binaphthyl core and is expected to have potential application in the materials of fluorescent sensors and chiral chromatographic packing for resolution ofracemic amino acid.     

Thermal polymerization of arylacetylenes: A stepwise activated monomer mechanism

Kinetics of the thermal polymerization of ATR(acetylene-terminated resin) model compounds, bisphenol A monobenzyl mono(ethynylaryl) ethers, was studied by means of GPC and the resulting oligomers were characterized by FTiR, UV, and H¹ NMR techniques. It was found that monomer was consumed rapidly at first, and later slowly, yielding a mixture of dimer, low oligomers (DP ⩽ 6) and higher ones. The concentrations of every lower species remained nearly constant throughout the polymerization (except first ten minutes). In order to account for these results, a new mechanism involving the activation of monomer and its attack on the end unit of the polymer chain was proposed. This is the first example of activated monomer mechanism (a. m. mechanism) for non-catalyzed polymerization of unsaturated monomers and, at the same time, the first example of stepwise a. m. mechanism. The structure of the resulting polymer will be discussed on the basis of this mechanism.     

2-(4-甲氧基苯基)-4,6-双(三氯甲基)-S-三嗪光引发剂的合成及其光聚合动力学性能研究

以对甲氧基苯甲腈和三氯乙腈为原料合成了光引发剂2-(4-甲氧基苯基)-4,6-双(三氯甲基)-S-三嗪(MBTT),通过傅里叶红外光谱仪、核磁共振仪和紫外吸收光谱对所合成的产物结构进行了表征.并利用实时红外(RT-IR)对该引发剂进行了光聚合反应动力学研究,考察了单体、引发剂浓度和光强对引发速率及单体转化率的影响.结果表明,MBTT是一种高效的紫外光引发剂,在引发剂用量为0.1%时光聚合的单体转化率就能达到90%;随着光强的增大,单体的双键转化率和最大反应速率都增大,诱导期缩短;双丙烯酸酯类单体的双键转化率比三丙烯酸酯类单体的双键转化率要高.     

含手性联萘冠醚侧基的聚苯型共轭聚合物的合成与表征

用钯催化的Suzuki缩聚法合成了一类新型主链为共轭聚苯结构,侧基数手性联萘冠醚取代基团的光学活性共轭聚合物。用1^H-NMR、紫外吸收光谱、园二色性、荧光光谱、热失重及差热分析等方法进行了表征。结果表明该光学活性聚苯具有良好的热稳定性和高的比旋度,在溶液中能络合碱金属离子,其荧光发射强度随着离子浓度的增大而逐渐降低。该光学活性聚苯的荧光光谱在410nm处出现最大发射峰,是一类潜在的发蓝光材料。     

Topotactic Solid-State Polymerization of Acenaphtylene by Radiation

ABSTRACT

The radiation-induced solid-state polymerization of acenaphthylene was carried out under vacuum at room temperature. The monomer and obtained polymer samples were investigated by UV, FTIR, DSC, TG, and powder X-ray diffraction methods to characterize the polymer and elucidate the polymerization mechanism. The polymer samples were crystalline with melting points ranging in 380-390°C interval. Polymerization takes place through vinyl groups by a radical mechanism and crystal structure of monomer and polymer studied by powder X-ray diffraction were quite similar. The space group for both were P22 ₁ 2 and cell parameters: a = 784.2 (6), b = 798.1(6), c = 1417.0(1) pm for monomer, and a = 791.7(8), b = 803.8(7), c =1431.0(1) pm for polymer. The similarity of crystal structures shows a topotactic polymerization of monomer.     

2,4-双(三氯甲基)-6-(4-甲氧基-1-苯乙烯基)-s-三嗪光引发剂的合成与聚合动力学研究

本研究以4-甲氧基苯甲醛和2,4-双(三氯甲基)-6-甲-基1,3,5-三嗪为原料合成了一种引发剂2,4-双(三氯甲基)-6-(4-甲氧基-1-苯乙烯基)-s-三嗪(BMT),并利用红外光谱、紫外光谱、核磁共振等手段对其结构进行表征.利用实时红外光谱研究其光聚合动力学性能,结果表明,不同引发剂浓度,不同单体和不同光强对单体双键转化率都有一定的影响.