Chromogenic Polymers - November 2009

Polymers can often be functional, yet boring materials found in white, shades of grey or black. So, it can be nice when polymers with more 'interesting' properties make life a bit more colourful and that's why this month we're focusing on the topic of chromogenic polymers!

Chromogenic polymers are particularly interesting, not only because of their capacity to change colour on demand, but also because there are different types which change colour because of different stimuli: thermochromic polymers change with heat; biochromic change when there is a biochemical reaction; magnetochromic alter with a change in magnetic field; photochromic change with light; electrochromic alter their colour when an electric field is applied; piezochromic change colour under pressure and ionochromic alter their colour when the ion concentration changes. In a similar fashion, thermotropic materials change their opacity in response to heat.

With all the different types of stimulus that can cause such noticeable changes it's no surprise that there is great potential for polymers with Chromogenic properties. Applications include glazing, display technology, sensor technology and other 'intelligent', 'responsive' materials. These can find homes in many industries, from packaging and medical to automotive, construction and beyond.

Abstracts

Please see below a selection of abstracts highlighted in the November Newsletter. These are records which relate to various forms of chromogenic polymers that have been recently added to the Polymer Library.

Click on the 7-digit accession numbers to find out about ordering a copyright-cleared full text copy of the items shown.

1050020 - PHOTOCHROMIC 3-DIMENSIONAL ACTUATOR BASED ON AN UNCROSSLINKED LIQUID CRYSTAL ELASTOMER
The synthesis of a photochromic liquid crystal polymer via acyclic diene metathesis polymerisation of a novel monomer, 4-butoxy-2'-(4-hex-5-enyloxy)-4'-(4-hex-5-enyloxybenzyloxy)azobenzene, containing a photochromic diazobenzene moiety, a phenyl benzoate nematic core, and two polymerisable olefin groups, and its characterisation by GPC, proton NMR, FTIR, UV-visible spectroscopy, polarised optical microscopy, DSC and WAXD, is described. The fabrication of photochromic actuators as a fibres or films by melt or solution processing respectively was investigated and their bending properties under polarised UV irradiation are discussed. 14 refs.
Journal of Materials Chemistry, 19, No.38, 14th Oct.2009, p.7124-7129, ISSN: 0959-9428, DOI: 10.1039/b909494f
Choi H J; Jeong K-U; Chien L-C; Lee M-H

1049896 - NEAR-INFRARED ELECTROCHROMIC POLY(ARYL ETHER)S BASED ON ISOLATED ELECTROACTIVE TETRAPHENYL-P-PHENYLENEDIAMINE MOIETIES
A series of near-infrared electrochromic aromatic poly(aryl ether)s containing N,N,N',N'-tetraphenyl-p-phenylenediamine (TPPA) moieties in their backbones were prepared by high-temperature polycondensation of 2,5-bis(diphenylamino)hydroquinone with various difluoro compounds. The resulting polymers were readily soluble in many organic solvents and showed high thermal stabilities, with high glass-transition temperatures in the range 182-205 degC and high char yields (more than 40% at 800 degC in nitrogen). The polymer films underwent reversible electrochemical oxidation with a high contrast ratio in both the visible range and near-infrared region, and also exhibited high coloration efficiency (CE), a low switching time, and stable electrochromic operation. 13 refs.
Journal of Polymer Science: Polymer Chemistry Edition, 47, No.20, 15th Oct.2009, p.5378-5385, ISSN: 0887-624X, DOI: 10.1002/pola.23587
Liou G S; Yen H J; Chiang M C

1049647 - SYNTHESIS AND STRUCTURE-PROPERTY RELATIONS OF A SERIES OF PHOTOCHROMIC MOLECULAR GLASSES FOR CONTROLLED AND EFFICIENT FORMATION OF SURFACE RELIEF NANOSTRUCTURES
The synthesis and properties of a new series of photochromic molecular glasses were studied, together with their structure-property relations, with reference to the controlled and efficient formation of surface relief nanostructures. The aim of the study was to establish a correlation between molecular structure, optical susceptibility, and the achievable surface relief heights. The molecular glasses consisted of a triphenylamine core and three azobenzene side groups attached via an ester linkage. The surface patterns of the molecular glasses were stable enough to be copied in a replica moulding process with polydimethylsiloxane. It was demonstrated that the replica could be used to transfer the surface pattern onto a common thermoplastic polymer, such as polycarbonate. 48 refs.
Advanced Functional Materials, 19, No.16, 24th Aug.2009, p.2630-2638, ISSN: 1616-301X, DOI: 10.1002/adfm.200900140
Walker R; Audorff H; Kador L; Schmidt H W

1049435 - DYNAMIC MECHANICAL ANALYSIS OF THERMOTROPIC COPOLYESTER-SHORT GLASS FIBER COMPOSITES
The effect of short glass fibres on the dynamic mechanical properties, molecular relaxations and microstructure of thermotropic copolyesters based on 1,4-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid was investigated by DMA, DSC and TGA. Mechanical relaxations were studied under torsion mode and the results correlated with the degree of molecular alignment and degree of crystallinity, as determined by wide-angle X-ray scattering. The results are discussed in terms of composite transition temperatures, decomposition temperatures, local and cooperative motions associated with the beta- and alpha- transitions, storage modulus, melting, molecular alignment and degree of crystallinity. 35 refs.
Polymers for Advanced Technologies, 20, No.10, Oct.2009, p.759-767, ISSN: 1042-7147, DOI: 10.1002/pat.1308
Romo-Uribe A; Alvarado-Tenorio M; Romero-Guzman E; Rejon L; Saldivar-Guerrero R

1049289 - POLYSTYRENE FUNCTIONALIZED CARBAZOLE AND ELECTROCHROMIC DEVICE APPLICATION
A PS functionalised carbazole macromonomer was synthesised and subjected to electrochemical oxidative polymerisation on an indium tin oxide-glass surface. The structure of the macromonomer was characterised by NMR spectroscopy, FTIR spectroscopy, UV vis spectroscopy and cyclic voltammetry and the spectroelectrochemical and electrochromic properties of the polymer films produced investigated. Polystyrene-carbazole/polyethylene dioxythiophene-based electrochromic devices were also fabricated and their electrooptical properties investigated. The devices showed reversible electrochemical oxidation, strong colour changes and switching times of 1.1s. 34 refs.
Synthetic Metals, 159, No.15-16, Aug.2009, p.1620-1627, ISSN: 0379-6779, DOI: 10.1016/j.synthmet.2009.04.026
Oral A; Koyuncu S; Kaya I

1048243 - PA KINKED UNIT-CONTAINING THERMOTROPIC LIQUID CRYSTALLINE COPOLYESTER WITH LOW GLASS TRANSITION TEMPERATURE AND BROAD PHASE TRANSITION TEMPERATURE
A phosphorus-containing thermotropic liquid crystalline copolyester with kinked unit was prepared by melting transesterification of terephthalic acid (TPA) with p-hydroxybenzoic acid, 2-(6-oxido-6H-dibenzo(c,e)[1,2]oxaphosphin-6-yl)benzene1,-4-diol, and bis(4-hydroxyphenyl) ether. The polymers showed a typical nematic mesophase that occurred at low temperatures and was maintained over a broad temperature range from 230 degC to more than 400 degC, and they low glass-transition temperatures ranging from 154.5 to 166.9 degC. These novel phosphorus-containing thermotropic liquid crystalline copolyester are potential useful for preparing various in situ reinforced polymer materials with good mechanical properties and flame retardancy. 28 refs.
Journal of Polymer Science: Polymer Chemistry Edition, 47, No.18, 15th Sept.2009, p.4703-4709, ISSN: 0887-624X, DOI: 10.1002/pola.23524
Heng-Zhen Huang; Li Chen; Yu-Zhong Wang

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