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Langmuir‐Blodgett films of photochromic polyglutamates, 10. The influence of the side chain architecture on the thermal and monolayer forming properties of “hairy rod”‐like polymers
Author(s) -
Menzel Henning,
Rambke Birgit
Publication year - 1997
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1997.021980706
Subject(s) - monolayer , side chain , mesogen , polymer , langmuir–blodgett film , crystallinity , materials science , phase (matter) , crystallography , liquid crystal , differential scanning calorimetry , polymer chemistry , chemistry , organic chemistry , composite material , nanotechnology , liquid crystalline , thermodynamics , physics , optoelectronics
The phase behavior of so called “hairy rod”‐like polymers with mesogenic elements in the side chains was investigated by means of differential scanning calorimetry and X‐ray diffraction and correlated with the properties of their monolayers at the air/water interface. The side chains of the polymers form a highly ordered (crystalline?) structure. The degree of crystallinity and the temperature of the phase transition to a less ordered liquid crystalline structure depend strongly on the side chain architecture. A higher degree of crystallinity is found for a decyloxy tail group than for a hexyl tail group, since alkoxy groups at the mesogenic elements can be packed more tightly. X‐ray diffraction proves that the side chains with a hexyl tail form a liquid crystalline phase, which may provide a fluid matrix for the rigid rod like backbones. The monolayers of these polymers with the side chains in a liquid crystalline phase at room temperature consist of soft domains and can be transferred to homogeneous Langmuir‐Blodgett films. By way of contrast the polymers in which the side chains are in a more highly ordered (crystalline) phase form stiff domains in the monolayers, resulting in isotherms with a shallow increase in surface pressure. Furthermore, a strong temperature dependence is found for the isotherms which can be interpreted to be a result of domain softening. The monolayers of the polymers with highly ordered side chains can be transferred only after inducing some disorder either photochemically or by increasing the temperature.