Poly(4-vinylpyridine)-based hydrogen bonded side-chain liquid crystal polymers (original) (raw)
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Supramolecular Side-Chain Liquid Crystalline Polymers with Various Kinked Pendant Groups
Macromolecules, 1998
Supramolecular side-chain liquid crystalline polymers with various kinked pendant groups are constructed from positional isomers of proton acceptor monomers and donor polymers (with different molecular weights) through hydrogen bonding. Monomer-monomer complexes of similar structures are built to compare the influence of the proton donors bound to the polymer backbones. Due to the bending effects introduced by the positional isomers, we are able to tune the molecular shape and thus to modify the mesogenic properties. New liquid crystalline properties are introduced by the kinked molecular geometry, and their kinked architecture is supported by the quantum mechanical calculations, the powder X-ray diffraction (XRD) patterns, and the deviation temperatures (∆T). Mesogenic properties of monomerpolymer complexes have similar trends as those of monomer-monomer complexes. Compared with analogous hydrogen-bonded (H-bonded) monomer-monomer complexes, higher isotropization temperatures and broader ranges of mesogenic phases (e.g., S A phase) are observed in the kinked supramolecular polymers. Significantly, H-bonded positional isomerism leads to dissimilar structures and properties of supramolecular side-chain liquid crystalline polymers.
Side-chain Liquid Crystal Polymers (SCLCP): Methods and Materials. An Overview
Materials, 2009
This review focuses on recent developments in the chemistry of side chain liquid crystal polymers. It concentrates on current trends in synthetic methods and novel, well defined structures, supramolecular arrangements, properties, and applications. The review covers literature published in this century, apart from some areas, such as dendritic and elastomeric systems, which have been recently reviewed.
Synthesis and structure of liquid-crystalline side-chain polymers
Pure and Applied Chemistry, 2000
The synthesis, structure and some properties of therrn6tropic liquid crystalline polymers with side xnesogenic groups are discussed. Approaches towards the synthesis of such systems are presented, as well as the data revealing the relationship between the molecular structure of the liquid-. crystalline polymers and the type of mesophase formed. The structure of smectic, nematic and cholesteric mesophases as well as models of chain packing in them are analyzed. The possibility to affect the strtcture of a liquid-crystalline polymer by an electric field is demonstrated.
Macromolecules, 1993
The synthesis and characterization of side-chain liquid crystal polymers baaed on atactic polystyrene and derivatized with differing mesogenic groups are described. These groups are cyano-, methoxy-, nitro-, and fluoroazobenzene and cyanobiphenyl. In each caw a butyl spacer is used to link the mesagenic group to the backbone. The cyano-and nitro-substituted azobenzenes exhibit a partially interdigitated smectic A phase, whereas the methoxy-and fluoro-substituted azobenzenes exhibit a smectic A phase in which the side chains overlap to a considerably greater extent. The dependence of the clearing temperaturea on the molecular structure of the mesogenic unit was found to be in accord with the behavior obaerved for low molar mass mesogens and other side-chain polymers having differing backbones. In contrast, the dependence of the glass transition temperature on the chemical nature of the mesogenic moiety appears to be influenced by the structure of the backbone. OMe Azo-OMe with phenol to yield 4-hydro~y-4~-subntituted ambenzene, 1, was performed by a standard method.# 4Cyano-4f-hydroxybiphsnyl was used as received from American Tokyo Kaaei, Inc. W other matariala were used as received from Aldrich Chemical Co.
Journal of Polymer Science Part A: Polymer Chemistry, 1989
Copolymerization of monomers containing the disiloxane unit in the spacer component and linear triple-core mesogens with comonomers containing linear double-core mesogens, or laterally attached triple-core mesogens was carried out radically. The effect of copolymer composition and monomer structure on the mesomorphic properties of the obtained copolymers was investigated in detail. The copolymers with a comonomer content up to 50 mol-%, exhibit an enantiotropic nematic phase, whereas the parent homopolymers containing triple-core mesogens exhibit a smectic phase. The copolymer containing more than 50 mol-To of the comonomer shows no mesophase. The isotropization temperature of the copolymers decreases with increasing comonomer content. However, the glass transition temperature is almost unchanged upon introduction of the comonomer unit. In case of copolymers containing laterally attached mesogens, a smectic phase was observed below the temperature range of the nematic phase. Consequently, the mesophase and the temperature range of the liquid-crystalline state can be controlled by the introduction of the comonomer unit whose parent homopolymer does not exhibit any mesophase.
The synthesis and thermal properties of polyepichlorohydrin side-chain liquid crystal polymers
European Polymer Journal, 2005
The synthesis and characterization of a new series of side-chain liquid crystal polyepichlorohydrin (PECH) polymers are described. The structures and thermal properties of the synthesized polymers were investigated using IR, NMR, polarized optical microscopy and differential scanning calorimetry. A substantial increase of the glass transition temperature with the degree of substitution of side-chain groups was observed. Polymers with a degree of substitution of side groups, of at least 60%, exhibited thermotropic liquid crystalline behaviour. The polymers present thermal liquid crystalline behaviour and form Schlieren and thread texture upon cooling from the isotropic phase, after annealing for 120 min at different temperatures. In addition, the thermal decomposition of PECHOPhPhCN was studied by thermogravimetry under both nitrogen and air environments. The temperature of the maximum decomposition rate was about 340°C. Weight loss decreased considerably after 350°C and was approximately 98% at 700°C. Chemical modification of functional polymers offers a simple method for obtaining liquid crystalline polymers whose transition temperature can be tailored by varying the amount of substitution, however complete substitution cannot be achieved.
Synthesis of side chain liquid crystalline copolymers and characterization of their polar structure
Journal of Polymer Science Part A: Polymer Chemistry, 1999
A series of side chain liquid crystalline copolymers having different spacer lengths, copolymer compositions, and chromophore types were synthesized and characterized both in the bulk and at the gas-water interface. Liquid crystalline properties were identified by differential scanning calorimetry (DSC), optical microscopy, and X-ray diffraction (XRD). Copolymer with spacer lengths 4, 5, 10, and 11 showed smectic A (S A ) phases with a bâ tonnet texture. The liquid crystalline (LC) phase stabilized as the spacer increased. Copolymers with different compositions were investigated both as monolayers and transferred films. The isotherms suggest nanodomain formation at the gas-water interface in copolymers with high nitrobiphenyl (NBP) content.