Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From ketone or ketene reactant
Patent
1995-06-26
1998-01-13
Truong, Duc
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From ketone or ketene reactant
528228, 528125, 528127, 528128, 544179, 544224, 544336, 544338, 544342, 544344, C08G 1200
Patent
active
057081239
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/DK94/00225, filed Jun. 9, 1994.
TECHNICAL FIELD
The present invention relates to a stable, electroactive material which when a potential is applied from the outside is subjected to one or more reversible redox reactions, for use in devices with an electrochromic display or another electrochromic colour change or in batteries, and to a process for the preparation of the stable, electroactive material with a single, reversible, redox-active condensed ring structure or in form of an oligomeric or polymeric material containing several such redox-active condensed ring structures.
The electroactive material according to the invention can be an electrochromic material of the type changing colour by one or more reversible redox reactions. The invention relates also to the use of such electrochromic materials in devices with an electrochromic display or as coating on windows.
The invention relates in addition to the use of the stable electroactive materials in rechargeable batteries.
BACKGROUND ART
Elektrochromism refers to a special property of particular materials, subsequently referred to as electrochromic materials, which in a reversible manner can change colour (spectral absorption and/or reflection) as a reaction to a potential applied from the outside.
Electrochromic materials can be widely used as they for instance can be used for electrochromic display for use in light signs or another display use where it is possible in no time to change showcards, to display "today's special" or the like. Electrochromic materials can also be used in form of window coatings allowing a subduing of the sunlight as required. In order to illustrate in greater detail the use of electrochromic materials in devices with an electrochromic display reference can for instance be made to an article by K. Bange and Th. Gambke "Electrochromic Materials for Optical Switching Devices", Adv. Mater. 2 (1990) No. 1, pages 10 to 16, as well as to U.S. Pat. No. 4,184,751 (Nicholson).
Numerous inorganic and organic electrochromic materials are known, among which the best tested and most used electrochromic material is wolframtrioxide WO.sub.3 displaying a cathodic coloration. Other electrochromic materials based on a cathodic coloration are for instance MOO.sub.3, V.sub.2 O.sub.5, Nb.sub.2 O.sub.5, and TiO.sub.2. Oxides of irridium, rhodium, nickel, and cobalt displaying an aniodic coloration can also be mentioned. Among the organic electrochromic materials viologenes can be mentioned, viz. dialkyl derivatives of 4,4'-bipyridinium salts, pyrazoline, pyridine, the tetrathiafulvalene system, and organometallic compounds, such as complexes of metal and diphthalocyanine. Polyaniline can furthermore be mentioned. The advantages of the organic electrochromic materials are their fast conversion capacity and their simple handling in the construction of electrochromic devices. An undesired and irreversible side effect of the weakly bound hydrogen ions and nitrogen ions is, however, one of the commonly known drawbacks of organic electrochromic materials as such side effects cause short lives and a poor stability to ultraviolet light.
EP Publication No. 32 991 (Engler et al.) discloses an electrochromic material in form of a polymer resin, to which electroactive molecules are covalently bonded and in which a non-electroactive ionic salt is incorporated. The object of the latter material is to improve the switching speed and the stability of the electrochromic material. These known materials present, however, still a poor stability. In addition, a rather indistinct change of colour appears, which is probably due to the structure of the materials, said structure not providing sufficient hindrance of interactions between the individual redox active units.
Nomura et al., J. Macromol. Sci.-Chem., A26 (2 & 3), pages 593 to 608 (1989) discloses an electrochromic material in form of a polymer complex between electrochromic polytetramethylene viologene (PVT) and poly(p-styrene sulphonic acid)
REFERENCES:
patent: 4184751 (1980-01-01), Nicholson
Bange et al., "Electrochromic Materials for Optical Switching Devices", Advanced Materials, 1990, pp. 10-16.
Nomura et al., "Electrochemical and Electrochromic of Polymer Complex Films Containing a Conductive Powder", J. Macromol. SCI-CHEM., A26(2&3), 1989, pp. 593-608.
J.o slashed.rgensen Mikkel
Johannsen Ib
NKT Research Center A/S
Truong Duc
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