Polymerization in liquid crystal — XVIII. Effect of the polyethyleneoxide main chain on the properties of polymers containing mesogenic groups in the side chain

Cser, F.; Nyitrai, K.; Horvath, J.; Hardy, G.

doi:10.1016/0014-3057(85)90229-0

Cited by 31 publications

(5 citation statements)

References 16 publications

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“…In the intermediate LC region a nematic phase was present, with typical Schlieren and threaded textures. In contrast to the unidentified S X phase reported for monomer 1 c in the literature 7) , in the present work microscopic observations clearly showed a nematic phase.…”

Section: Mesomorphic Properties Of the Monomerscontrasting

confidence: 81%

“…In a recent thesis of Jansen 17) the possible consequences of these poly(ether) groups on the phase transition temperature of the parent polycarbonates have been discussed extensively. Data of the present polycarbonates were compared with literature values of several corresponding (homo)polyethers 5,7,18,19) . Also predictions of the T g and T i of polycarbonates and corresponding polyethers were made by the additive group contribution method of Van Krevelen 20) .…”

Section: Influence Of Carbonate and Ether Content On Phase Transitionmentioning

confidence: 99%

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Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Jansen

Addink

Nijenhuis

et al. 1999

Macromol. Chem. Phys.

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SUMMARY:The mesomorphic properties and thermal stability of side-chain LC polycarbonates with alkoxyphenyl benzoate side groups having a short spacer and alkoxy tails ranging from 1 to 8 carbon atoms were studied by DSC, X-ray diffraction and polarized light optical microscopy. All polymers have a smectic A structure. Mesogens having short tails organize preferably in a monolayer structure, and mesogens having long tails in a double layer structure. A sharp increase in the clearing temperatures and enthalpies as a function of tail length was observed. No clear relation between the tail length and the glass transition temperature was found. Both the T g and the clearing temperature show a strong dependence on the molecular weight. Up to about M -w = 20 000 a rapid increase in phase transition temperatures with increasing molecular weight was observed, eventually levelling off to a constant maximum value. The LC polycarbonates were found to be thermally stable up to about 200 8C. At higher temperatures, random chain scission, resulting in a rapid decrease in molecular weight, and unzipping, resulting in the formation of a five-membered cyclic carbonate, are the main initial degradation mechanisms. The degraded polymers have lower transition temperatures than the original ones.

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Section: Mesomorphic Properties Of the Monomerscontrasting

confidence: 81%

Section: Influence Of Carbonate and Ether Content On Phase Transitionmentioning

confidence: 99%

Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Jansen

Addink

Nijenhuis

et al. 1999

Macromol. Chem. Phys.

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“…The polymerization route has also been considered by several authors. Earlier studies on the polymerization of epoxy compounds bearing different mesogenic groups gave only poorly characterized oligomers with no liquid crystalline behavior or unidentified mesophases 16, 17. Tuan et al described two series of polyoxyranes bearing 4‐cyanobiphenyl and p ‐methoxyphenyl benzoate groups linked to the polyoxyethylene main chain through alkyl spacers of different lengths 18, 19.…”

Section: Introductionmentioning

confidence: 99%

Studies on the modification of poly(ω‐bromoalkyl‐1‐glycidylether)s with 4′‐methoxybiphenyl‐4‐oxy mesogenic groups

Montornés¹,

Reina²,

Ronda³

2005

J. Polym. Sci. A Polym. Chem.

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A series of poly[ω‐(4′‐methoxy‐biphenyl‐4‐oxy)alkyl‐1‐glycidylether]s were synthesized by chemically modifying the corresponding poly(ω‐bromoalkyl‐1‐glycidylether)s with the sodium salt of 4‐hydroxy‐4′‐methoxybiphenyl. New high‐molecular‐weight side‐chain liquid‐crystalline polymers were obtained with excellent yields and almost quantitative degrees of modification. They were all insoluble in THF and other common solvents. Characterization by 13C NMR confirmed that all the polymers had the expected structure. The liquid crystalline behavior of the polymers was analyzed by DSC and polarized optical microscopy, and mesophase assignments were confirmed by X‐ray diffraction studies. Polymers that had alkyl spacers with n = 2 and 4 were smectic C, those that had spacers with n = 6 and 8 were nematic cybotactic, and those that had longer spacers (n = 10 and 12) were smectic C again. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5998–6006, 2005

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“…PECH has already been used as a precursor of some liquid crystalline polymers − and various other polymers. − Chemical modification of PECH occurs mainly as a nucleophilic substitution reaction at the chloromethyl pendant group, leaving untouched the asymmetric carbon atoms of the polymer backbone; the tacticity of the resulting polymer therefore should not be altered. Several authors have reported however that cleavage of the backbone polymer chain ,,,− and cross-linking 10,11,14,17,18 are important side reactions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Glycidyl Azide Polymers Using Isotactic and Chiral Poly(epichlorohydrin)s

Brochu¹,

Ampleman²

1996

Macromolecules

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Isotactic and chiral glycidyl azide polymers (GAPs) have been synthesized by the reaction of isotactic and chiral poly(epichlorohydrin)s (PECHs) with sodium azide in dimethylformamide at 95 °C. The azidation does not affect the isotacticity of the chains, but the polymer backbone is degraded in the process; a GAP of high molecular weight (100 kg/mol) is nevertheless obtained. Despite the high isotacticity of the polymer chains, the GAPs are not crystalline. Long reaction times favor the branching and/or the cross-linking of the polymer. The isotactic and chiral PECHs used as starting materials for the GAP syntheses have been prepared by the Vandenberg process using racemic or chiral monomers, leading thus to partially ((RS)-PECH) or completely ((R)- or (S)-PECH) isotactic polymers, respectively. They have been split into a soluble and an insoluble fraction by acetone extraction. The fractionation of chiral PECH withdraws from the polymer the incompletely isotactic chains coming from the presence of monomers of opposite configuration in the chiral epichlorohydrin or from a defective polymerization process. The population of crystals remaining in the insoluble chiral PECH fraction is thus more homogeneous, leading to an improved crystallinity and a higher melting temperature.

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Polymerization in liquid crystal — XVIII. Effect of the polyethyleneoxide main chain on the properties of polymers containing mesogenic groups in the side chain

Cited by 31 publications

References 16 publications

Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Studies on the modification of poly(ω‐bromoalkyl‐1‐glycidylether)s with 4′‐methoxybiphenyl‐4‐oxy mesogenic groups

Synthesis and Characterization of Glycidyl Azide Polymers Using Isotactic and Chiral Poly(epichlorohydrin)s

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