A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Lyotropic Side Chain Polymer Liquid Crystals
Abstract The incorporation of liquid-crystal-forming molecules into large polymeric structures has opened up a wide and diverse new field in both organic and physical chemistry. This new interest has centred mainly on the synthesis, physical properties and technical applications of thermotropic polymer liquid crystals (PLCs), about which much will be mentioned in this book in Chapters 3 and 7. Lyotropic PLCs too have found many useful applications, for example in the production of new materials such as ‘Kevlar’ and other polyamides.1,2 However, a further subclass of these polymeric materials, side chain lyotropic PLCs, has received comparatively little attention. The majority of the examples of such structures contain surfactant molecules as the monomeric side chains. These surfactant moieties are composed of a hydrophobic and a hydrophilic part and as such may be termed ‘amphiphilic’. In the monomeric state surfactants may aggregate into micellar structures which, in concentrated systems, may further pack together to form one or more liquid crystal structures. This phenomenon highlights a major difference between thermotropic and lyotropic side chain liquid crystals: in the former it is the packing of molecules which gives the degree of ordering required, whilst for the latter it is the packing of the micellar aggregates which gives rise to liquid crystal formation. Polymerization may affect this process in a number of ways, for example by altering the size and shape of micelles3 or even by preventing micellization altogether. Here we might predict that the degree of polymerization of the polymer chain may be influential, since for the majority of micellar aggregates there is an upper limit to the aggregation number. Furthermore, variation in the polymer type and points of attachment of the side chains and head groups makes possible a large variety of PLC structures. To date only a few have been studied.
Lyotropic Side Chain Polymer Liquid Crystals
Abstract The incorporation of liquid-crystal-forming molecules into large polymeric structures has opened up a wide and diverse new field in both organic and physical chemistry. This new interest has centred mainly on the synthesis, physical properties and technical applications of thermotropic polymer liquid crystals (PLCs), about which much will be mentioned in this book in Chapters 3 and 7. Lyotropic PLCs too have found many useful applications, for example in the production of new materials such as ‘Kevlar’ and other polyamides.1,2 However, a further subclass of these polymeric materials, side chain lyotropic PLCs, has received comparatively little attention. The majority of the examples of such structures contain surfactant molecules as the monomeric side chains. These surfactant moieties are composed of a hydrophobic and a hydrophilic part and as such may be termed ‘amphiphilic’. In the monomeric state surfactants may aggregate into micellar structures which, in concentrated systems, may further pack together to form one or more liquid crystal structures. This phenomenon highlights a major difference between thermotropic and lyotropic side chain liquid crystals: in the former it is the packing of molecules which gives the degree of ordering required, whilst for the latter it is the packing of the micellar aggregates which gives rise to liquid crystal formation. Polymerization may affect this process in a number of ways, for example by altering the size and shape of micelles3 or even by preventing micellization altogether. Here we might predict that the degree of polymerization of the polymer chain may be influential, since for the majority of micellar aggregates there is an upper limit to the aggregation number. Furthermore, variation in the polymer type and points of attachment of the side chains and head groups makes possible a large variety of PLC structures. To date only a few have been studied.
Lyotropic Side Chain Polymer Liquid Crystals
Hall, P. J. (author) / Tiddy, G. J. T. (author)
1992-01-01
36 pages
Article/Chapter (Book)
Electronic Resource
English
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