Blending as a method of tuning reflection wavelength and helical twisting sense in films and composites of liquid crystalline cellulose derivatives

J. M G Cowie, Gillian I. Rodden

Research output: Contribution to journalArticle

Abstract

Ethyl cellulose (EC) with a degree of substitution of 2.41 and a fully acetylated sample (AEC) of this material, form lyotropic liquid crystalline solutions in chloroform and acrylic acid. Above 35 wt% polymer, the solutions exhibit chiral nematic phases that reflect light selectively at a specific wavelength ?0. For EC solutions the helical twist sense of the chiral nematic phase is left handed, whereas the AEC solutions are right handed. The ?0 and handedness of the system can be tuned to a given set of values by preparing solutions of EC and AEC in different blend ratios. These can be converted to films or composites, that retain the chiral nematic structure and the corresponding chiro-optical properties, by either casting from chloroform or photopolymerising the (EC + AEC)/acrylic acid solutions to form blend composites of EC/AEC in poly(acrylic acid). The most effective way to control the chiro-optical properties of the dry films was to use the photopolymerisation technique to form composite films of the blends. Such films can be used either as coatings to reflect visible light of a particular colour, or act as a protective layer to reduce UV degradation. © 2002 Published by Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)3415-3419
Number of pages5
JournalPolymer
Volume43
Issue number12
DOIs
Publication statusPublished - 15 Apr 2002

Fingerprint

Cellulose derivatives
Tuning
Crystalline materials
Wavelength
Composite materials
Liquids
carbopol 940
Chloroform
Optical properties
Photopolymerization
Composite films
Polymers
Casting
Substitution reactions
ethyl cellulose
Color
Degradation
Coatings

Keywords

  • Cellulose derivatives composite formation
  • Lyotropic liquid crystalline
  • UV protection

Cite this

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abstract = "Ethyl cellulose (EC) with a degree of substitution of 2.41 and a fully acetylated sample (AEC) of this material, form lyotropic liquid crystalline solutions in chloroform and acrylic acid. Above 35 wt{\%} polymer, the solutions exhibit chiral nematic phases that reflect light selectively at a specific wavelength ?0. For EC solutions the helical twist sense of the chiral nematic phase is left handed, whereas the AEC solutions are right handed. The ?0 and handedness of the system can be tuned to a given set of values by preparing solutions of EC and AEC in different blend ratios. These can be converted to films or composites, that retain the chiral nematic structure and the corresponding chiro-optical properties, by either casting from chloroform or photopolymerising the (EC + AEC)/acrylic acid solutions to form blend composites of EC/AEC in poly(acrylic acid). The most effective way to control the chiro-optical properties of the dry films was to use the photopolymerisation technique to form composite films of the blends. Such films can be used either as coatings to reflect visible light of a particular colour, or act as a protective layer to reduce UV degradation. {\circledC} 2002 Published by Elsevier Science Ltd.",
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Blending as a method of tuning reflection wavelength and helical twisting sense in films and composites of liquid crystalline cellulose derivatives. / Cowie, J. M G; Rodden, Gillian I.

In: Polymer, Vol. 43, No. 12, 15.04.2002, p. 3415-3419.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Cowie, J. M G

AU - Rodden, Gillian I.

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N2 - Ethyl cellulose (EC) with a degree of substitution of 2.41 and a fully acetylated sample (AEC) of this material, form lyotropic liquid crystalline solutions in chloroform and acrylic acid. Above 35 wt% polymer, the solutions exhibit chiral nematic phases that reflect light selectively at a specific wavelength ?0. For EC solutions the helical twist sense of the chiral nematic phase is left handed, whereas the AEC solutions are right handed. The ?0 and handedness of the system can be tuned to a given set of values by preparing solutions of EC and AEC in different blend ratios. These can be converted to films or composites, that retain the chiral nematic structure and the corresponding chiro-optical properties, by either casting from chloroform or photopolymerising the (EC + AEC)/acrylic acid solutions to form blend composites of EC/AEC in poly(acrylic acid). The most effective way to control the chiro-optical properties of the dry films was to use the photopolymerisation technique to form composite films of the blends. Such films can be used either as coatings to reflect visible light of a particular colour, or act as a protective layer to reduce UV degradation. © 2002 Published by Elsevier Science Ltd.

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