Studies on synthesis and thermal characterisation of thermotropic liquid-crystalline poly(benzylidene-ether)s containing alkanones and methylene spacers in the main chain

Krishnasamy, Balaji; Murugavel, S. C.

doi:10.1080/02678292.2012.671965

Cited by 10 publications

(2 citation statements)

References 83 publications

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“…The thermal stability of the polymers decreases as the acid methylene spacer length increases 45. The presence of ether linkage in the spacer units is expected to introduce flexibility to the polymer chain and bring down thermal stability 46. The stability among the aliphatic polyesters is given as P1 > P2 > P3 > P4.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, thermal, and photocrosslinking studies of thermotropic liquid crystalline poly(benzylidene‐ether)esters containing α,β‐unsaturated ketone moiety in the main chain

Muthusamy

Krishnasamy

Murugavel

2013

J. Polym. Sci. A Polym. Chem.

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A series of poly(benzylidene-ether)esters containing a photoreactive benzylidene chromophore in the main chain were synthesized from 2,6-bis(4-hydroxy-3-methoxybenzylidene)cyclohexanone (BHMBCH) with various aliphatic and aromatic diacid chlorides by an interfacial polycondensation technique. The intrinsic viscosity of the synthesized homo and copolymers determined by Ubbelohde viscometer was found to be 0.12 to 0.17 dL/g. The molecular structure of the monomer and polymers was confirmed by FT-IR, 1 H NMR, and 13 C NMR spectral analyses. These polymers were studied for their thermal stability and photochemical properties. Thermal properties were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It was found that the polymers were stable up to 280 C and start degrading thereafter. Increase in acid methylene spacer length decreased the thermal stability. The self-extinguishing property of the synthe-sized polymers was studied by calculating the limiting oxygen index (LOI) value using a Van Krevelen's equation. The influence of the length of methylene spacer on phase transition was investigated using DSC and odd-even effect has been observed. Hot-stage optical polarizing microscopic (HOPM) study showed that most of the polymers exhibited birefringence and opalescence properties. The photolysis of liquid crystalline poly(benzylidene-ether)esters revealed that a,b-unsaturated ketone moiety in the main chain dimerises through 2p þ 2p cycloaddition reaction to form a cyclobutane derivative and leads to crosslinking.

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Section: Resultsmentioning

confidence: 99%

Synthesis, thermal, and photocrosslinking studies of thermotropic liquid crystalline poly(benzylidene‐ether)esters containing α,β‐unsaturated ketone moiety in the main chain

Muthusamy

Krishnasamy

Murugavel

2013

J. Polym. Sci. A Polym. Chem.

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“…The thermal stability of the polymers decreases as the acid methylene spacer length increases [42]. The presence of methylene spacer units is expected to introduce flexibility to the polymer chain and bring down thermal stability [43]. The char yield among the aliphatic polyesters at 650 ○ C is given as P1 > P2 > P3 > P4.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

Synthesis and Characterization of Liquid Crystalline Polyesters Containing α,β-unsaturated Ketone Moiety in the Main Chain Derived from 2,6-bis(4-hydroxybenzylidene)cyclohexanone

et al. 2020

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A series of polyesters containing a photosensitive benzylidene chromophore in the main chain were synthesized from 2,6-bis(4-hydroxybenzylidene)cyclohexanone with various aliphatic and aromatic diacid chlorides by interfacial polycondensation technique. The intrinsic viscosity of the synthesized homo and copolymers determined by Ubbelohde viscometer and found to be 0.13-0.18 dL/g. The molecular structure of the monomer and polymers was confirmed by Fourier Transform infrared, 1 H NMR and 13 C NMR spectroscopic techniques. These polymers were studied for their thermal stability and photochemical properties. Thermal properties were evaluated by thermogravimetric analysis and differential scanning calorimetry. It was found that the polymers were stable up to 238°C and start degrading thereafter. Increase in acid methylene spacer length decreases the thermal stability. The self-extinguishing property of the synthesized polymers was studied by calculating the limiting oxygen index value using Van Krevelen equation. The influence of the length of methylene spacer on phase transition was investigated and it was found that isotropic temperature decreases on increasing the acid methylene spacer length. Hot-stage optical polarizing microscopic study showed that synthesized polymers exhibit grainy texture in the temperature range of 115-127°C. The photolysis of liquid crystalline polyesters revealed that α,β-unsaturated ketone moiety in the main chain dimerizes through 2π+2π cycloaddition reaction to form a cyclobutane derivative that leads to crosslinking.

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Synthesis, Characterization and Properties of Some Main-Chain Ferrocene-Based Polymers Containing Aromatic Units

Amer

Wang

et al. 2013

J Inorg Organomet Polym

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Studies on synthesis and thermal characterisation of thermotropic liquid-crystalline poly(benzylidene-ether)s containing alkanones and methylene spacers in the main chain

Cited by 10 publications

References 83 publications

Synthesis, thermal, and photocrosslinking studies of thermotropic liquid crystalline poly(benzylidene‐ether)esters containing α,β‐unsaturated ketone moiety in the main chain

Synthesis, thermal, and photocrosslinking studies of thermotropic liquid crystalline poly(benzylidene‐ether)esters containing α,β‐unsaturated ketone moiety in the main chain

Synthesis and Characterization of Liquid Crystalline Polyesters Containing α,β-unsaturated Ketone Moiety in the Main Chain Derived from 2,6-bis(4-hydroxybenzylidene)cyclohexanone

Synthesis, Characterization and Properties of Some Main-Chain Ferrocene-Based Polymers Containing Aromatic Units

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