Search results for "polymers"

Water-soluble polyesters from long chain alkylesters of citric acid and poly(ethylene glycol)

2007

Abstract Long chain aliphatic alcohols have been used as model compounds to develop a preparative method for a water-soluble material, which could be a carrier for triacontanol, a highly hydrophobic plant growth regulator. New polyesters from long chain aliphatic (C = 12, 18 and 22) mono-1-alkyl citrates and poly(ethylene glycol) were synthesized and characterized by NMR spectroscopy. The polyester containing the triacontyl moiety was obtained from mono-1-triacontyl citrate, which was synthesized from the corresponding alcohol extracted from the Agave fourcroydes . The molecular weight M ¯ n of the polyesters depends on experimental conditions during synthesis such as reaction time, atmosph…

Properties of trialkylamines as catalysts of resoles synthesis

2000

A series of the syntheses of phenol–formaldehyde resoles was carried out in the presence of trimethyl-, triethyl-, tripropyl-, and tributylamines and sodium hydroxide as catalysts for this process. The rate constants were calculated for the partial reactions identified in the synthesis. Also, the performance properties of the resins obtained and the hardened resin samples were estimated in simple tests. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 898–902, 2000

Fluctuating Interfaces in Liquid Crystals

2008

We review and compare recent work on the properties of fluctuating interfaces between nematic and isotropic liquid-crystalline phases. Molecular dynamics and Monte Carlo simulations have been carried out for systems of ellipsoids and hard rods with aspect ratio 15:1, and the fluctuation spectrum of interface positions (the capillary wave spectrum) has been analyzed. In addition, the capillary wave spectrum has been calculated analytically within the Landau-de Gennes theory. The theory predicts that the interfacial fluctuations can be described in terms of a wave vector dependent interfacial tension, which is anisotropic at small wavelengths (stiff director regime) and becomes isotropic at l…

Shear Modulus of an Irreversible Diblock Copolymer Network from Self-Consistent Field Theory

2019

Using self-consistent field theory, we investigate the stretching-induced microphase separation in an irreversibly cross-linked polymer network composed of diblock copolymer chains and estimate its...

Electrically conductive hydrogel composites made of polyaniline nanoparticles and poly(N-vinyl-2-pyrrolidone)

2006

Abstract A novel electrically conductive composite material, consisting of polyaniline (PANI) nanoparticles dispersed in a polyvinyl pyrrolidone (PVP) hydrogel, was prepared ‘in situ’ by water dispersion polymerisation (DP) of aniline using PVP as steric stabiliser, followed by γ-irradiation induced crosslinking of the PVP component. Conversion yield of aniline into PANI particles was determined via HPLC and gas chromatography, while structural confirmation of the synthesised polymer was sought by FTIR. Morphology and dimensions of PANI particles into the coloured, optically transparent hydrogel was determined by electronic microscopy; moreover, swelling behaviour of composite hydrogels in …

¿Conjugated? Copolymers from a Pechmann Dye Derivative

2016

Thin Films by Multilayer Build-Up of Electron Transport Materials

2003

We present the synthesis and the electrochemical characterization of polymeric electron transport materials, synthesized by polycondensation of substituted triazines and α,ω-dihaloalkanes. They can be reversibly reduced with the least negative potential at −0.39 V, which is below the reduction potential of oxygen. In addition, the formation of polyelectrolyte multilayers is possible by the electrostatic self-assembly method. This multilayer formation takes place in a very defined way up to thirty double layers. An example of one of the polymeric triazine electron transport materials synthesized and a schematic diagram of a self-assembled multilayer film.

Organoboron Polymers for Photovoltaic Bulk Heterojunctions

2010

We report on the application of three-coordinate organoboron polymers, inherently strong electron acceptors, in flexible photovoltaic (PV) cells. Poly[(1,4-divinylenephenylene)(2,4,6-triisopropylphenylborane)] (PDB) has been blended with poly(3-hexylthiophene-2,5-diyl) (P3HT) to form a thin film bulk heterojunction (BHJ) on PET/ITO substrates. Morphology may be modulated to give a high percentage of domains (10-20 nm in size) allowing exciton separation. The photoelectric properties of the BHJs in devices with aluminium back electrodes were imaged by light beam induced current (LBIC) and light beam induced voltage (LBIV) techniques. Open circuit voltages, short circuit currents and overall …

PEDOT:Poly(1-vinyl-3-ethylimidazolium) dispersions as alternative materials for optoelectronic devices

2008

Liquid Crystalline Orientation of Semiconducting Nanorods in a Semiconducting Matrix

2008

This paper describes the synthesis of narrowly distributed block copolymers consisting of a hole conducting triarylamine block and an anchor block via RAFT polymerization. The anchor block is thereby introduced via a reactive ester approach. Block copolymers with dopamine anchor groups bind to oxidic semiconductors like TiO 2 , SnO 2 , and ZnO. Thus, it becomes possible to cover inorganic electron conducting (acceptor) nanomaterials with a corona of an organic hole conducting (donor) polymer like poly(triphenylamine), giving new hybrid materials. The poly(triphenylamine) grafted to inorganic nanorods allows the preparation of stable nanorod dispersions in appropriate solvents. At higher con…