Two new “H” type of indole‐based chromophores were designed and successfully introduced to the polymeric system, the resultant polymers demonstrated enhanced NLO effects, good processability, thermal stability and nearly excellent transparency, indicating the advantages of “H” type chromophore moieties. And they could be promising candidates for the practical applications as new photonic materials.
The synthesis, layer‐by‐layer deposition, and electro‐copolymerization of precursor polyelectrolyte multilayer ultrathin films with thiophene and carbazole electroactive groups are described. The interest is in observing an electrochemical cross‐linking approach towards a highly ordered ultrathin film that contains two types of monomers to result in possible layer‐limited homo‐ and copolymerization. A uniform linear growth with alternate deposition of the polyelectrolytes is observed. The multilayer films were then electrochemically polymerized anodically by cyclic voltammetry (CV), which results in copolymerization between two different electroactive groups. Cross‐linking of the layers was verified by CV and spectroelectrochemistry data with very good linear electro‐copolymerizability.
In this work, we report the design of a new multi‐functional, water‐soluble conjugated polymer integrating both a DNA intercalator and a redox label. Based on this multi‐functional conjugated polymer, we develop a sequence‐specific electrochemical DNA sensor, where the acridine unit serves as the basis for sequence discrimination, and the ferrocene label provides the electrochemical signal. Moreover, the conjugated polythiophene helps transfer electrons from ferrocene to the electrode. This sensor provides a new way for rapid and convenient detection of DNA targets.
A mathematical model describing interfacial radical polymerization‐based film formation on hydrogels is elucidated. A glucose oxidase‐mediated multistage initiation reaction is used to accomplish interfacial film formation. A polymer concentration‐dependent diffusion coefficient is used to reflect the changing mass transport conditions as the film develops. Model predictions of the film thickness as a function of the species concentrations agree well with experiments. The model predicts that the degree of initiation reaction delocalization with the enzyme‐mediated initiation system is significantly higher than an enzyme‐independent system, thus affecting the film growth rate and structure. The mass transport properties of the film and its adhesion to the underlying substrate are also investigated.
A new π‐conjugated charge‐transfer‐type copolymer of electron‐donating thiophene and electron‐accepting quinoxaline was prepared by organometallic polycondensation. The polymer was soluble in organic solvents such as tetrahydrofuran, and showed a UV‐vis peak at long wavelengths of 598 nm in chloroform and 629 nm in the film. Its film exhibited a χ(3) peak in the resonance region with a χ(3) value comparable to that of regioregular head‐to‐tail poly(3‐hexylthiophene‐2,5‐diyl).
The establishment of advanced living/controlled polymerization protocols allows for engineering synthetic polymers in a precise fashion. Combining advanced living/controlled polymerization techniques with highly efficient coupling chemistries facilitates quantitative, modular, and orthogonal functionalization of synthetic polymer strands at their chain termini as well as side‐chain functionalization. The review highlights the current status of selected post‐functionalization techniques of polymers via orthogonal ligation chemistries, major characteristics of the specific transformation chemistry, as well as the characterization of the products.
Reactions between the ethylene groups in the backbone of conjugated polymers under UV illumination and heat treatment result in the cross‐linking of the main polymer chains. The cross‐linking leads to two simultaneous results in the polymer: excellent solvent resistance and increased bandgap. Using this reaction, three‐color polymer light‐emitting diodes (PLEDs) with a multi‐layer structure can be easily realized by a dry photo‐pattern in an active‐gas‐free environment. Multi‐layer blue devices with dramatically enhanced efficiency can also be achieved conveniently.
Summary: The synthesis of well‐defined uniform and spherical sub‐micron polymeric spheres, specifically poly[styrene‐co‐(glycidyl methacrylate)] (PSGMA) with a uniform size distribution and surface chemical functionality, is described. It is shown that the surface can be modified with a multi‐amine functional polymer, polyethyleneimine (PEI), most likely through covalent bonding in addition to electrostatic attraction. The PEI acts both as a stabilizing agent and a complexation agent for the deposition of noble metal Ag nanoparticles.
Reaction of PSGMA samples with excess PEI, and its TEM image. 相似文献
The various end‐to‐end distances of four‐junction polymers are investigated. The sizes of the different kinds of equal length branches and the backbone of two different polymers, with either nine or eleven branches, are estimated by means of both renormalization‐group and MC calculations. The comparisons of first‐order ε = 4 − d predictions with the MC results are satisfactory. The same trends are present in both techniques. The excluded‐volume interactions from additional branches further expand the various parts of the chains so that internal branches are larger than external ones. The branch ratios in the eleven‐branch case are expanded even more than the corresponding ratios of the nine‐branch polymer.
A polyvinylpyrrolidone (PVP)‐based fluorescent film with stable optical properties is successfully prepared in one pot without any additive. The reaction mechanism of ring‐opening and self‐crosslinking of linear PVP is proposed and demonstrated. The morphologies and the nanostructures of the fluorescent film as well as the unmodified film are investigated. The dye is incorporated into the film networks via covalent linkages, thus leading to the highly stable optical properties. The facile and effective synthesis approach opens a new way for the design of other multi‐functional composite materials based on linear PVP.
A two‐armed polymer with a crown ether core self‐assembles to produce macroporous films with pores perpendicularly reaching through the film down to the substrate. A possible assembling mechanism is discussed. The pore size can be conveniently adjusted by changing the solution concentration. These through‐hole macroporous films provide a template for fabricating an array of Cu nanoparticle aggregates.
Fluorescent image patterns of a substituted acetylene polymer film with a large FFV were successfully obtained by a µCP method using several kinds of chemical ink compounds. PO and SCA generated positive‐type fluorescent image patterns. On the other hand, an ethanolic solution of DNT generated a negative‐type fluorescent image pattern due to a significant quenching effect. An NMP solution of NR gave a two‐color image pattern due to an intermolecular energy transfer from PTMSDPA to NR.
The synthesis of cationic mono‐(6‐O‐(1‐vinylimidazolium))‐ß‐cyclodextrin with toluenesulfonate as the corresponding anion is described. Free‐radical copolymerization of the resulting host–guest complex with N‐isopropylacrylamide or N,N‐diethylacrylamide yielded copolymers showing a temperature‐controlled solubility window in water. The impact of different anionic guests and salt concentrations on solubility behavior was investigated via turbidity measurements.
Surface initiated living‐radical polymerization (SIP) based on dithiocarbamate iniferters has been used to create molecularly imprinted core‐shell (CS) nanoparticles. Using this approach, propranolol, morphine and naproxen have been successfully imprinted in particle shells (the latter could not be imprinted using conventional aqueous‐based CS methods). Rebinding properties of the imprinted particles appear to be similar to those made by alternative methods. The living radical initiation mechanism makes it possible to build complex multi‐layer particles sequentially. As a demonstration, multi‐layer propranolol‐imprinted particles were generated. Two additional functional shells were grown over the imprinted shell, while the propranolol binding was retained, albeit at a reduced level.
In this work we describe the synthesis of multi‐sensitive aqueous microgel particles with incorporated conducting poly(3,4‐ethylenedioxythiophene) (PEDOT) nanorods. We demonstrate that the loaded amount of PEDOT nanorods as well as their morphology can be varied by controlling the reaction conditions such as monomer concentration and alcohol concentration in aqueous phase. Obtained microgels can be stimulated by changes in the environment temperature as well as by the repulsion/attraction forces within polymeric network due to the reversible oxidation/reduction of the conjugated polymer. Microgels with unique properties can be operated in colloidal systems or used as building blocks for the preparation of nanostructured films.
The complexation of bile acids with various solvated polycations was studied. A one‐to‐one complex was precipitated when an aqueous solution of cholic acid sodium salt (CA) was mixed with aqueous solutions of 3,3‐ionene and grew to form crystals with needle‐like morphology, 3 millimeters in length. Hydrogen bonding of hydroxyls at the steroid face and the spacing between cationic sites of polycations were crucial for the formation of the giant needle.
Crossed polarizing microscopic photograph of the complex composed of cholic acid sodium salt and 3,3‐ionene. 相似文献
Versatile synthetic methods towards a variety of thiophene‐nucleobase hybrid systems are reported. Adenine‐ and thymine‐based modified nucleosides characterized by a bithiophene unit linked to the C5′ or C8 position through an ethylenamino or an ethylensulfanyl bridge were synthesized and successfully polymerized in the presence of FeCl3. The self‐organization properties of the pure polymers as well as their mixtures ‐ with complementary nucleobases ‐ were investigated by means of optical microscopy and AFM in cast film showing complex supramolecular structures resulting from the interplay of multiple intermolecular interactions.
The synthesis of an oriented liquid‐crystalline photoresponsive polymer, prepared by polymerization of mono‐ and di‐acrylates, both of which contain azobenzene chromophores, is reported. The prepared free‐standing polymer film shows strong reversible photoinduced deformation upon exposure to unpolarized UV light at 366 nm, as a result of an optically induced isomeric change of the azobenzene moieties in the polymer network. The synthesis process is relatively simple and more efficient compared to conventional ones, and can be used to synthesize other liquid‐crystalline photoresponsive polymers. The use of this photoresponsive polymer film as an optical high‐pass/low‐pass switch under UV or natural light irradiation for a laser beam is demonstrated. This photoresponsive polymer may have applications in robotic systems, artificial muscles, and actuators in microelectromechanical systems (MEMS) and labs on chips.
Microporous films consisting of two‐dimensionally ordered void structures ‐ so‐called honeycomb films ‐ were produced by evaporation of polymer solutions under high humidity. Two types of poly(vinyl cinnamate)s were used: A newly synthesized amphiphilic poly(vinyl cinnamate) and a mixture of a commercial poly(vinyl cinnamate) and an amphiphilic polyion complex. Photo‐crosslinking of the honeycomb structure could be achieved by UV irradiation while completely retaining the film morphology. The crosslinked films showed excellent stability against organic solvents.
An efficient procedure to create oriented polymer films with strongly anisotropic properties is described. It is based on a two‐step process combining a photochemical and a thermal aligning step. The orientation of the polymer parallel or perpendicular to linearly polarised incident light can be adjusted. The method presented allows for simple fabrication of films with anisotropic absorption and emission characteristics with a dichroism of 0.7 and a fluorescence anisotropy of about 8.
