Synthesis and photophysical properties of new carbon-chain copolymers with europium-containing and carbazole fragments in pendant chains

Functionalized polynorbornenes with terpyridine and carbazole groups in pendant chains were prepared by metathesis copolymerization. The polymeric products prepared react with europium thenoyltrifluoroacetonate to form new carbon-chain copolymers with different ratios of organic and europium-containing units. The polymeric materials prepared were characterized by IR and NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and elemental analysis. All the europium-containing copolymers exhibit strong metal-centered photoluminescence in solution and in thin film.     

Terbium-containing copolymers based on the norbornene functional derivatives. Synthesis, photoluminescent and electroluminescent properties

New carbazole- and terpyridine- containing norbornene derivatives were synthesized and structurally characterized. On the basis of these compounds by the method of metathesis polymerization copolymers were obtained with carbazole and terpyridine fragments in side chains. The synthesized copolymers react with terbium pyrazolonate complex to form the terbium-containing polymeric materials exhibiting the metalcentered photo- and electroluminescence.     

Light scattering and luminescence studies on self-aggregation behavior of amphiphilic copolymer micelles

The self-aggregation behavior of three amphiphilic graft copolymers, oligo(9,9-dihexyl)fluorence-graft-poly(ethylene oxide) (OHF-g-PEO), with different architectures was studied by dynamic and static light scattering (DLS and SLS) in combination with fluorescence spectroscopy and transmission electron microscopy (TEM). The formation of self-assembled polymeric micelles was confirmed by SLS and TEM. DLS and SLS analyses showed that the architecture of graft copolymers has a dramatic effect on critical aggregation concentration (CAC), micelle size distribution, apparent aggregation number (Nagg app), and apparent molecular weight of polymer aggregates (Mw,agg app). An architecture-dependent excimer emission, resulting from the pi-pi stacking of the oligofluorene backbones, was also observed from the photoluminescence spectra of the micelle aqueous solutions, which indicated a strong intermolecular interaction among the polymeric molecules. The excimer emission was further investigated by time-resolved fluorescence spectroscopy.     

PREPARATION AND PROPERTY OF POLYMERIC PENDANT Ru(bpy)_3~(2+) COMPLEXES

Polymeric pendant Ru(bpy)_3~(2+) complexes were prepared from homopolymer and copolymers of 4-methyl-4'-vinyl-2,2'-bipyridine (Vbpy). Vbpy was prepared from 4-methylpyridine. The comonomers were styrene (St), acrylic acid (AA), N-vinylpyrrolidone (Pyr), 4-vinylpyridine (Vpy), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), acrylonitrile (AN) and N-ethyl-4-vinylpyridium bromide (EQ-Vpy). The fraction of the pendant Ru(bpy)_3~(2+) repeating unit in the polymeric complex was 0.022 to 0.052. Absorption maximum, molar extinction coefficient, emission maximum and relative emission intensity of the polymeric complexes were studied.     

Head-to-Head Polymers. XXII. Toward the Synthesis of Pure Head-to-Head Poly(methyl Methacrylate): Copolymerization of 2,3-Dimethylmaleic Anhydride and Ethylene

Copolymerization of 2,3-dimethylmaleic anhydride and ethylene has been accomplished under ethylene pressure (up to 1000 psi) with AIBN as the initiator. The copolymers were obtained at relatively low yield and only of moderate molecular weight. The incorporation of 2,3-dimethylmaleic anhydride units into the copolymer is about 20 mol% at 1000 psi and is 33 mol% at 500 psi of ethylene pressure. Unlike maleic anhydride-ethylene copolymers, alternating 2,3-dimethylmaleic qnhydride-ethylene copolymers of reasonable molecular weight have not yet been prepared. 2,3-Dimethylmaleic anhydride-ethylene copolymers could be hydrolyzed to the polymeric acids and quantitatively esterified to the polymeric methyl esters. Both anhydride and ester copolymers have been characterized spectroscopically and by their thermal behavior.     

Preparation and self-assembly of pH-sensitive amphiphilic comb-shaped copolymer containing long fluorinated side chains

Novel pH-sensitive amphiphilic comb-shaped copolymers containing long fluorinated side chains, which combined the characteristics of pH-sensitivity from pendent tertiary amine groups, unique hydrophobic and fluorophobic characteristic from the fluorinated moieties and hydrophilicity from the poly (ethylene glycol) segments, were designed and synthesized via radical polymerizaion of 2-(Dimethylamino) ethyl methacrylate (DMAEMA), poly (ethylene glycol) methyl ether methacrylate (PEGMA) and homemade fluorinated macromonomer (PHFBMA-GMA). The physicochemical properties of polymeric micelles prepared therefrom were investigated. The chemical structures of the copolymers were characterized by GPC, FTIR and ¹H-NMR. The critical micelle concentrations (CMC) of the copolymers in different pH (5.0 and 7.4) were determined by fluorescence spectroscopy. Larger CMCs could be obtained in lower pH since the pronation of DMAEMA moieties enhanced the hydrophilicity. With increasing the amount, as well as the molecular weight, of PHFBMA-GMA, CMC decreased significantly. As pH decreased, particle size, as well as zeta potential of the polymeric micelles increased significantly, indicating significant pH-sensitivity of the polymeric micelles. Furthermore, larger polymeric micelles were obtained with larger amount, as well as higher molecular weight, of PHFBMA-GMA. Transmission electron microscopy (TEM) showed that the morphological shapes of the copolymers performed spherical micelles. The cytotoxicity test showed that the comb-shaped copolymers performed extremely low cytotoxicity. The pH-sensitive polymeric micelles prepared from the amphiphilic comb-shaped copolymers containing long fluorinated side chains could be potential candidates for nanotanks for hydrophobic or fluorophobic molecules and drug carriers and the facile preparation might fit for large scale industrialization.     

A-B-A Triblock and (A-B)n Segmented Block Copolymers of Styrene and Ethylene Oxide via Thermal Iniferters

A free radical technique is described for the synthesis of tri- and multiblock copolymers of styrene and ethylene oxide through polyethylene oxide-based thermal “iniferters.” The mono- or dihydroxy-terminated oligomeric polyethylene oxides were chemically transformed to the secondary amine terminated species. Thiocarba-mylation and oxidation of the amine groups gave rise to macro- or polymeric thiuram disulfides called macro- or polymeric “iniferters,” respectively. Thermal polymerization of styrene in the presence of the macro iniferter led to the formation of their perfect triblock copolymers, with styrene forming the central block. Utilization of the polymeric iniferter, on the other hand, give rise to (A-B)_n type segmented copolymers containing as many as 3 (A-B) sequences. The length of each block could be regulated by the choice of the appropriate iniferter and its relative concentration with respect to the monomer. The iniferters and the block copolymers were characterized.     

从聚酯合成聚酯-聚醚多嵌段共聚物

研究直接以聚酯为原料,合成聚酯-聚醚多嵌段共聚物。研究了反应机理、链段结构对反应的影响以及由此法制备的多嵌段共聚物的链段序列结构。实验结果表明,链段相容性对聚合物法的影响至为重要,链段相容性不仅决定了所得嵌段共聚物的组成均一性,而且还决定了某一链段结构的多嵌段共聚物能否用聚合物法制备。     

Micelle or polymersome formation by PCL-PEG-PCL copolymers as drug delivery systems

Polymeric micelles and polymersomes may have great potential as the drug delivery vehicles for solubilization of hydrophobic drugs.     

Morphology control in polymeric multiphase systems with block copolymers and structured latexes

Some application possibilities of block copolymers for the morphology control in polymeric multiphase systems are reviewed. The microdomain formation of block copolymers in the solid state is illustrated in the case of functionalized block copolymers and for interpolymer complexes. The preparation of “hairy latex” by emulsion polymerization in the presence of hydrophilic-hydrophobic block copolymers is shown in connection with their applications in the controlled agglomeration process of latexes and for the preparation of polymer particles having microvoids. The surface activity of block copolymers in polymeric oil-in-oil systems is illustrated for silicone oil filled polymers. These materials have a low kinetic friction coefficient and act as reservoir systems with the lubricant incorporated in the polymer matrix.     

两亲性壳聚糖衍生物的制备及其包覆量子点

以天然壳聚糖为功能性高分子的骨架,通过西弗碱还原法,以正辛醛和端醛基聚乙二醇单甲基醚(mPEG aldehyde,mPEG-ald)修饰壳聚糖,制备了具有亲疏水性质的N-辛基化-N-mPEG化壳聚糖衍生物(N-octyl-N-mPEG-chitosan,OPEGC),并且以此两亲性壳聚糖衍生物包覆量子点制备了水溶性聚合物量子点纳米粒子.用FTIR、1H-NMR对壳聚糖衍生物进行了结构表征.制备的水溶性胶束,用动态光散射(DLS)测试其流体力学直径与分布,研究了烷基链接枝比率对粒径大小的影响,研究结果表明:烷基链接枝率越高,聚合物胶束粒径越小.以芘为分子探针,通过荧光光谱法测定了壳聚糖衍生物的临界胶束浓度(CMC)为2.032×10-2mg/mL,并对水溶性聚合物量子点纳米粒子进行了紫外、荧光及形貌表征,结果表明得到了荧光发射产率高的聚合物量子点纳米粒子,且尺寸均一、水溶性好.     

Polyfluorene Homopolymers: Conjugated Liquid‐Crystalline Polymers for Bright Blue Emission and Polarized Electroluminescence

Since the first report on blue electroluminescence from a soluble poly(9,9‐di‐alkylfluorene), fluorene‐based homo‐ and copolymers have evolved as a major class of polymeric emitters for highly efficient organic light‐emitting diodes. This Review is concerned with the particular properties of soluble derivatives of polyfluorene homopolymers with respect to emission properties, control of color stability and efficiency in electroluminescence, alignment in thin layers and polarized emission. A major point of discussion is the origin of unwanted emission contributions in the photoluminescence and electroluminescence spectra of solid layers as well as concepts to avoid these contributions in order to ensure stable device performance. Further, the alignment of polyfluorenes and their use in polarized light‐emitting diodes is addressed.     

Supramolecular Polymerization of Polymeric Nanorods Mediated by Block Copolymers

Introducing a second component is an effective way to manipulate polymerization behavior. However, this phenomenon has rarely been observed in colloidal systems, such as polymeric nanoparticles. Here, we report the supramolecular polymerization of polymeric nanorods mediated by block copolymers. Experimental observations and simulation results illustrate that block copolymers surround the polymeric nanorods and mainly concentrate around the two ends, leaving the hydrophobic side regions exposed. These polymeric nanorods connect in a side-by-side manner through hydrophobic interactions to form bundles. As polymerization progresses, the block copolymers gradually deposit onto the bundles and finally assemble into helical nanopatterns on the outermost surface, which terminates the polymerization. It is anticipated that this work could offer inspiration for a general strategy of controllable supramolecular polymerization.     

Structural features of polymeric silicon glycerolate hydrogels

Structural features of polymeric silicon glycerolate hydrogels based on tetrafunctional silicon glycerolates were investigated using model process, namely, hydrolytic transformation of difunctional silicon glycerolates, by IR and ¹H NMR spectroscopy, elemental analysis, atomic emission spectrometry. The possibility of forming a polymer network containing Si—O—Si and Si—OCH₂CH(OH)CH₂O—Si fragments was demonstrated. The molecular weight of the sub-chains in the network was calculated using Flory—Rehner approach based on the mechanical properties of the swollen network of flexible polymeric chains.     

New chiral photochromic menthone-containing homopolymers and copolymers - synthesis, phase behaviour and photo-optical properties

A new approach for the preparation of photosensitive materials for coloured data recording and storage is advanced. This approach involves the synthesis of copolymers containing nematogenic and combined (-)-arylidene-p-menthan-3-one chiral photochromic fragments in one monomer unit. The conditions for the formation of an LC phase in the chiral photochromic homopolymers as a function of the structure of the side groups have been identified; for a new series of copolymers, the effect of their composition on the phase behaviour and photooptical properties is considered. Planarly oriented films of the copolymers show selective light reflection in the UV, visible, and near IR spectral regions. The photochemical behaviour of the homopolymers and copolymers in dilute solution and as films has been studied. In these systems, under UV radiation, the E-Z isomerization of the (-)-arylidene-p-menthan-3-one fragment is the dominating process. The kinetic features of the photoprocess are revealed, and the effective quantum yields calculated. The isomerization process leads to dramatic changes in the anisometry of the chiral side groups, and the helical twisting power decreases. Therefore, as a result of UV radiation of films of the copolymers, the selective light reflection peak is shifted to a longer wavelength spectral region. This means that such polymeric films can be considered as promising materials for colour data recording and as storage media.     

SYNTHESIS OF POLYESTER-POLYETHER MULTIBLOCK COPOLYMERS FROM POLYESTERS

A polymeric method was explored for the preparation of polyester-polyether multiblock copoly-mers using polyesters and polpethers as starting materials. The mechanism of the reaction and theeffect of the segment structure on it, the segment sequence of the block copolymers prepared havebeen studied. It has been shown that to the polymeric method the degree of compatibility betweenstarting polyester and polyether is of paramount importance, which determines not only the com-positional homogeneity of the block copolymers formed but also the success of the polymeric methodto get the block copolymers of the expected structure.     

Orientational phenomena in comb-shaped liquid crystal polymers induced by laser beam irradiation

Action of the laser illumination on optical properties of liquid crystalline (LC) comb-shaped acrylic and methacrylic copolymers containing cyanobiphenyl mesogenic groups and azo dye fragments has been studied. Under an illumination the cis-trans configurational changes of dye fragments take place and reorientation of the side groups towards a direction perpendicular to the electric vector of the actinic light occurs. As a result the photoinduced optical birefringence (δn = 0.05-0.11) appears. The detailed study of dichrotic and optical properties of polymeric films, kinetics and relaxation of δn, as well as mechanism of orientational transformations during a laser illumination are discussed. The induced optical anisotropy of the films can be changed reversibly by rotating the electric vector of the laser beam in respect to the film that may be used in reversible optical data storage.     

Thermal studies on the starch-g-copolymers prepared from two terpene acrylate monomers under oxidative conditions

The simultaneous thermal studies (TG/DTG/DSC) coupled with the FTIR analysis of the gaseous decomposition products created under oxidative heating of starch-g-poly(neryl acrylate) and starch-g-poly(geranyl acrylate) copolymers have been presented. To these studies, the copolymers with the following grafting percents (G) were selected: starch-g-poly(neryl acrylate) copolymers: 36.6?±?0.3%, 40.3?±?0.4%, 42.8?±?0.4% and starch-g-poly(geranyl acrylate) copolymers: 28.9?±?0.2%, 32.4?±?0.6%, 35.6?±?0.4%. The performed tests proved that the thermal resistance of the copolymers was strongly dependent on their G values, despite a small difference in the G values between the samples. The slight increase (ca. 6.2–6.7%) in the G value caused the significant drop of the thermal stability of all the studied materials. The TG/DTG/DSC studies confirmed at least three-stage decomposition mechanism of the copolymers where simultaneous pyrolysis, oxidation, dehydration and decarboxylation processes took place. The TG/FTIR analyses showed the emission of various structure fragments; among them, one can mention the creation of some organic fragments such as aldehyde, acid, alkene, alkane, furan fragments, CH₄ and inorganic species (CO₂, CO, H₂O) as a result of the oxidative decomposition processes of the studied copolymers. In addition, the conducted studies demonstrated similar decomposition course and mechanism for both types of the copolymers, regardless of the monomer type used to the graft process.

     

Selective deposition and self-assembly of triblock copolymers into matrix arrays for membrane protein production

To improve the stability of cell membrane mimics, there has been growing interest in the use of block copolymers. Here, we present an easy approach to create an array of planar polymeric matrices capable of hosting membrane proteins. The array of polymeric matrices was formed by the selective deposition of triblock copolymers onto an array of hydrophilic islands situated within a hydrophobic background. The thickness of these matrices corresponds to the length of a single polymer chain. These polymeric matrices were used to host cell-free expressed membrane proteins, and offers a prototype from which a membrane protein array can be created for diagnostics or drug discovery purposes.     

Synthesizing amphiphilic block copolymers through macromolecular azo-coupling reaction

This communication reports a new approach to synthesize amphiphilic block copolymers. The copolymers with well-defined structures were synthesized by macromolecular azo-coupling reaction between the diazonium salt of aniline-functionalized PEG and the polymeric blocks with a terminal suitable for the azo-coupling reaction.