Synthesis and morphology of polyethylene chains grafted onto the surface of crosslinked polystyrene microspheres

The bifunctional comonomer 4-(3-butenyl) styrene was used to synthesize crosslinked polystyrene microspheres (c-PS) with pendant butenyl groups on their surface via suspension copolymerization. Polyethylene chains were grafted onto the surface of c-PS microspheres (PS-g-PE) via ethylene copolymerizing with the pendant butenyl group on the surface of the c-PS microspheres under the catalysis of metallocene catalyst. The composition and morphology of the PS-g-PE microspheres were characterized by means of Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. It is possible to control the content of PE grafted onto the surface of c-PS microspheres by varying the polymerization time or the initial quantity of pendant butenyl group on the surface of c-PS microspheres. Investigation on the morphology and crystallization behavior of grafted PE chains showed that different surface patterns could be formed under various crystallization conditions. Moreover, the crystallization temperature of PE chains grafted on the surface of c-PS microspheres was 6 degrees C higher than that of pure PE. The c-PS microspheres decorated by PE chains had a better compatibility with PE matrix.

Synthesis and characterization of polyethylene chains grafted onto the sidewalls of single-walled carbon nanotubes via copolymerization

Polyethylene (PE) chains grafted onto the sidewalls of SWCNTs (SWCNT-g-PE) were successfully synthesized via ethylene copolymerization with functionalized single-walled carbon nanotubes (f-SWCNTs) catalyzed by rac-(en)(THInd)(2)ZrCl2/ MAO. Here f-SWCNTs, in which alpha-alkene groups were chemically linked on the sidewalls of SWCNTs, were synthesized by Prato reaction. The composition and microstructure of SWCNT-g-PE were characterized by means of H-1 NMR, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analyses (TGA), field-emission scanning electron microscope (FESEM), and transmission electron microscope (TEM). Nanosized cable-like structure was formed in the SWCNT-g-PE, in which the PE formed a tubular shell and several SWCNTs bundles existed as core. The formation of the above morphology in the SWCNT-g-PE resulted from successfully grafting of PE chains onto the surface of SWCNTs via copolymerization. The grown PE chains grafted onto the sidewall of the f-SWCNTs promoted the exfoliation of the mass nanotubes. Comparing with pure PE, the physical mixture of PE/f-SWCNTs and in situ PE/SWCNTs mixture, thermal stability, and mechanical properties of SWCNT-g-PE were higher because of the chemical bonding between the f-SWCNTs and PE chains.

Liquid crystal properties of a mesogenic polyacetylene, poly(11-[(4 '-heptoxy-4-biphenylyl)carbonyloxy]-1-undecyne)

The liquid crystalline properties of a mesogenic poly(1-alkyne) and the corresponding monomer were studied using transmission electron microscopy, X-ray diffraction, polarizing optical microscopy and differential scanning calorimetry. The monomer exhibits a monotropic smectic A phase and a metastable crystalline phase. The rigid polymer backbones do not prevent the mesogenic moieties from packing into smectic A and B phases in the temperature ranges 127.6 - 74.1degreesC and 74.1degreesC - room temperature, respectively, on cooling from the isotropic melt.

Synthesis and characterization of novel polythiophenes containing poly(ethylene oxide) side chains

Thiophene copolymers and their derivatives with poly(ethylene oxide) side chains were synthesized. The starting monomers were 3-hexylthiophene and 2-(3-thienyl) ethanol with poly(ethylene oxide) grafted to the side chains. New functionalized polythiophenes were prepared by both chemical oxidation with FeCl3 and electropolymerization. The conjugating polymers were characterized. The structures of the polythiophene derivatives agreed with the design.

Shear induced molecular alignments of a side-chain liquid crystalline polyacetylene containing biphenyl mesogens

Mesomorphic properties of a side chain liquid crystalline polyacetylene, poly(11-{[(4'-heptyloxy-4-biphenylyl)carbonyl]oxy}-1-undecyne) (PA9EO7), are investigated using polarized optical microscope, X-ray diffraction, and transmission electron microscope. Polymer PA9EO7 forms enantiotropic smectic A and smectic B phases. It also exhibits an additional high order smectic phase, a sandwich structure consisting of different molecular packing of biphenyl mesogenic moieties from that of alkyl spacers and terminals, when it is prepared from its toluene solution. Shearing the polymer film at its smectic A phase generates banded texture with the alignment of the backbones parallel to the direction of shear force. While at its high order smectic phase, the mesogen pendants of the polymer are arranged parallel to the direction of shear. The different mesomorphic behaviors arise from different molecular alignments influenced by the fluidity.

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4 '-bipy)(H2O)4](4-abs)2 center dot nH(2)O (4,4 '-bipy=4,4 '-Bipyridine; 4-abs=4-aminobenzenesulfonate) (M=Co, n=1; M=Mn, n=2)

Two novel compounds, [Co(4,4'-bipy)(H2O)(4)](4-abS)(2).H2O (1) and [Mn(4,4'-bipy)(H2O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H2O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H2O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C22H30CoN4O11S2, monoclinic P2(1), a = 11.380(2) Angstrom, b = 8.0274(16) Angstrom, c = 15.670(3) Angstrom, alpha = gamma = 90degrees, beta = 92.82(3)degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H2O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C22H32WN4O12S2, monoclinic P2(1)/c, a = 15.0833(14) Angstrom, b = 8.2887(4) Angstrom, c = 23.2228(15) Angstrom, alpha = gamma = 90degrees, beta = 95.186(3)degrees, Z = 4.

The luminescence of the phosphor Sr2ZrO4 with one-dimensional chains structure

A new type of phosphor Sr2ZrO4 with one-dimensional structure was prepared by solid reaction and its luminescence is seen at room temperature. The excitation and emission spectra were measured and display broad maximum at 354 nm and 386 nm respectively. The mechanism of this luminescence is ascribed to charge transfer.

Corona poling of liquid crystalline polymers with nitroazobenzene side chains

The orientational behavior of liquid crystalline polymers with para-nitro azobenzene as side chains under electric field was studied by UV-visible spectroscopy. The results showed that lambda(max) of the poled polymer films was around 394nm, compared to that of the unpoled films, the absorption decreased due to poling. The orientational parameters increased linearly with the increase of the electric field. The temporal stability of the poled polymer film is good at room temperature. This kind of materials showed promise application as nonlinear optical component in photorefractive polymers.

Synthesis, characterization and ionic conductivity of solid polymer electrolytes based on modified alternating maleic anhydride copolymer with oligo(oxyethylene) side chains

Three comb polymers (CP) based on modified alternating methyl vinyl ether/maleic anhydride copolymer with oligo-oxyethylene side chains of the type -O(CH2CH2O)(n)CH3 were synthesized and characterized, and the ionic conductivity of CP/salt complexes is reported. The conductivity of these complexes was about 10(-5)-10(-6) S cm(-1) at room temperature. The conductivity, which displayed non-Arrhenius behaviour, was analysed using the Vogel-Tammann-Fulcher equation. The conductivity maxima appear at lower salt concentration, when CP has longer side chains. Infrared (i.r.) was used to study the cation-polymer interaction. I.r. results also indicate that the ester in CP might decompose at 140 degrees C and reproduce the maleic anhydride ring. (C) 1997 Elsevier Science Ltd.

Ion-conducting polymers based on modified alternating maleic anhydride copolymer with oligo(oxyethylene) side chains

Comb-like polymers (CPs) based on modified alternating methyl vinyl ether/maleic anhydride copolymer with oligo(oxyethylene) side chains of the type -O(CH2CH2O)(n)CH3 were synthesized and characterized, and complexed with lithium salts to form amorphous polymer electrolytes. Maximum conductivity close to 1.38 x 10(-4) S/cm was achieved at room temperature and at a [Li]/[EO] ratio (EO = ethylene oxide) of about 0.066. The temperature dependence of ionic conductivity suggested that the ion transport was controlled by segmental motion of the polymer, shown by linear curves obtained in Vogel-Tammann-Fulcher plots. The ionic conductivity maximum moved to a higher salt concentration as the temperature increased, indicating that a larger number of charge carriers can be transferred through polymer chains, of which free volume is increased at higher temperature. IR results indicated that the ester in CPs might decompose at 140 degrees C and reproduce the maleic anhydride ring.

Ionic conductivity of solid polymer electrolytes based on modified alternating maleic anhydride copolymer with oligo(oxyethylene) side chains

Comb-like polymers (CP) based on modified alternating methyl vinyl ether/maleic anhydride copolymer with oligo-oxyethylene side chains of the type -O(CH2CH2O)(n)CH3 have been synthesized and characterized, and complexed with lithium salts to form amorphous polymer electrolytes. CP/salt complexes showed conductivity up to 10(-5)Scm(-1) at room temperature. The temperature dependence of ionic conductivity suggests that the ion transport is controlled by segmental motion of the polymer, shown by linear curves obtained in Vogel-Tammann-Fulcher plots. The ionic conductivity maximum moves to a higher salt concentration as the temperature increases. IR results indicate that the ester in CP might decompose at 140 degrees C and reproduce the maleic anhydride ring.

Studies on water-swellable elastomers .2. Thermal properties and crystalline behavior of amphiphilic graft copolymers with poly(ethylene glycol) side chains

The thermal properties and crystalline structure of the amphiphilic graft copolymers CR-g-PEG600, CR-g-PEG2000, and CR-g-PEG6000 using chloroprene rubber (CR) as the hydrophobic backbone and poly(ethylene glycol) (PEG) with different molecular weights as the hydrophilic side chains were studied by DSC and WAXD. The results showed that a distinct phase-separated structure existed in CR-g-PEGs because of the incompatibility between the backbone segments and the side-chain segments. For all the polymers studied, T-m2, which is the melting point of PEG crystalline domains in CR-g-PEG, decreased compared to that of the corresponding pure PEG and varied little with PEG content. For CR-g-PEG600 and CR-g-PEG2000, T-m1, which is the melting point of the CR crystalline domains, increased with increasing PEG content when the PEG content was not high enough, and at constant PEG content, the longer were the PEG side chains the higher was the T-m1. The crystallite size L-011 of CR in CR-g-PEGs increased compared to that of the pure CR and decreased with increasing PEG content. (C) 1997 John Wiley & Sons, Inc.

The synthesis of dendrimers bearing alkyl chains and their behavior at air-water interface

A new kind of amphiphilic polyether dendrimer bearing eight alkyl chains at the periphery were synthesized step by step using the convergent method. Their structures were confirmed by FT-IR spectra, H-1 NMR spectra and mass spectra etc. The pi-A isotherms, hysteresis and molecular area-time curves at air water interface were reported. These results showed that they could form stable monolayers at water surface.

Synthesis and ionic conductivity studies of solid polymer electrolytes based on modified alternating maleic anhydride copolymer with oligo(oxyethylene) side chains

Comb-like polymers (CP) based on modified alternating methyl vinyl ether/maleic anhydride copolymer with oligo-oxyethylene side chains of the type-O(CH2CH2O)(n)CH3 have been synthesized and characterized, and complexed with LiNO3 to form an amorphous polymer electrolyte. CP/salt complexes showed conductivity up to 10(-5) S/cm at room temperature. The temperature dependence of ionic conductivity suggests that the ion transport is controlled by segmental motion of the polymer, shown by linear curves obtained in Vogel-Tammann-Fulcher plots. The ionic conductivity maximum moves to a higher salt concentration as the temperature increases. IR results also indicate that the ester in CP might decompose at 140 degrees C and reproduce the maleic anhydride ring.

Lithium ion conducting polymer electrolytes based on alternating maleic anhydride copolymer with oligo-oxyethylene side chains

A comb polymer with oligo-oxyethylene side chains of the type -(CH2CB2O)(12)CH3 was prepared from methyl vinyl ether/maleic anhydride copolymer and poly (ethylene glycol) methyl ether. The polymer can dissolve LiClO4 salt to form homogeneous amorphous polymer electrolyte. The ac ion conduction was measured using the complex impedance method, and conductivities were investigated as functions of temperatures and salt concentration. The complexes were first found to have two classes of glass transition which increase with increasing salt content, The optimum conductivity attained at 25 degrees C is in the order of 5.50 x 10(-6)Scm(-1). IR spectroscopy was used to study the cation-polymer interaction.