The mechanical behaviour of monodomain nematic side‐chain liquid‐crystalline elastomers containing azoderivatives as pendant groups or crosslinkers has been studied under UV irradiation and in the darkness at different temperatures. From the evaluation of the opto‐mechanical experiments, the mechanical efficiency, kinetic rates, activation energies and the isomerization mechanism of the azocompounds in the liquid‐crystalline matrix could be determined, as well as the effect of the chemical constitution of the azobenzene derivatives and their role in the elastomeric network.
Ring‐opening metathesis polymerization (ROMP) was used for the synthesis of monolithic capillary columns with inner diameters of 200 µm. The resulting polymeric monoliths were characterized by inverse size‐exclusion chromatography (ISEC). Surface functionalization was carried out in situ using 2‐(N,N‐dimethylaminoethyl)norborn‐5‐ene‐2‐ylcarboxylic amide ( 1 ). The resulting functionalized monoliths were successfully used in anion‐exchange chromatography of oligodeoxynucleotides.
By using an advanced polarization modulation infrared reflection adsorption spectroscopy (PM‐IRRAS) device it is possible to study the photopolymerization of an ultrathin layer of a porphyrin monomer in real time. The method can be compared with the indirect UV/Vis method previously introduced by our group. With PM‐IRRAS it is possible to analyze polymerization kinetics of photopolymerization at various temperatures to determine the activation energy of the reaction.
Poly(2,5‐thienylene vinylene) (PTV), an insoluble conjugated polymer, can be readily prepared in various shapes of different nanodimensions by the chemical vapor deposition polymerization of 2,5‐bis(chloromethyl)thiophene. The bischloromethyl monomer in the vapor phase is activated at 600 °C. The activated monomer vapor is deposited at room temperature on the surface of various substrates to prepare polymeric films, fibers, tubes etc., which are then thermally converted into PTV. PTV thin films can be carbonized thermally to produce graphitic compositions that contain sulfur atoms. Electrical conductivities of FeCl‐doped PTV and carbonized films are reported.
A PFS/PLA block copolymer was studied to probe the effect of strong surface interactions on pattern formation in PFS block copolymer thin films. Successful synthesis of PFS‐b‐PLA was demonstrated. Thin films of these polymers show phase separation to form PFS microdomains in a PLA matrix, and ultrathin films (<5 nm) formed SINPATs on silicon and mica. The SINPATs consisted of strongly surface‐adsorbed PLA blocks on top of which the PFS blocks dewetted into sphere‐like features. The lateral spacing between these features was regular, and was typically much larger than the length scale associated with regular block copolymer phase separation.
Summary: A high‐molecular‐weight fluorinated poly(aryl ether) with a 4‐bromophenyl pendant group has been synthesized based on a bromo‐bisphenol. A phosphonic acid derivative is readily prepared from this in high conversion yield. The phosphonated polymer possesses excellent thermal, oxidative, and dimensional stability, low methanol permeability, and reasonable proton conductivity, and may be a candidate polymeric electrolyte membrane for fuel cell applications.
Synthesis of a poly(aryl ether) with a phosphonic acid group. 相似文献
Summary: Amphiphilic hyperbranched polyester (H20‐AM) with methacrylate end groups was synthesized based on hyperbranched aliphatic polyester (Boltorn™ H20). Narrow‐dispersed crosslinkable vesicles were obtained by dissolving H20‐AM in water, and characterized by laser light scattering and TEM. The hollow structural vesicle is composed of around 350 H20‐AM molecules, having a radius of around 40 nm and of 1.9 × 106 g · mL−1. The vesicles were fixed by crosslinking of methacrylate groups to form shape‐persistent structures.
TEM images of the crosslinked vesicles at lower magnification. 相似文献
Summary: A water‐soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono‐6‐thio‐β‐cyclodextrin with poly(propylene glycol) bis(2‐aminopropyl ether) ( ≈ 2 000) in the presence of sodium borohydride in N,N‐dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA‐cleavage reagent.
A typical TEM image of gold nanoparticle aggregate 2 . 相似文献
Dynamic lattice Monte Carlo simulations on a simple cubic lattice were used to study the association behavior of heteroarm star copolymers with two types of chemically different arms (miktoarm star). The effect of architecture and composition (number and length of arms) on self‐assembly was investigated. Simulations revealed substantial differences between associates formed by linear diblock copolymers and by star copolymers. It was also observed that the length of arms considerably influences the association behavior. Apart from the structural characteristics of the whole associate, the properties of individual stars in associates were also studied. These results provide detailed information on the inner structure of associates.
Blue‐light‐emitting 2,7‐carbazole‐based conjugated copolymers have been prepared by Yamamoto or Suzuki cross‐coupling reactions. By introducing highly substituted aromatic comonomers, fully soluble high‐molecular‐weight copolymers have been obtained. Moreover, these amorphous polymeric materials exhibit good thermal stability and interesting redox properties. All these features make these new conjugated polymers highly promising for the development of single‐polymer‐layer blue‐light‐emitting diodes.
