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A series of alkyl-substituted and unsubstituted poly(3,4-alkylenedioxythiophene)s were synthesized electrochemically using 3,4-alkylenedioxythiophene derivative monomers where either the size of the alkylenedioxy ring or the nature of the pendent group was varied. The specific systems studied include 3,4-ethylenedioxythiophene (EDOT), 2-methyl-2,3dihydrothieno [3,4-b][1,4] (BuDOT-Xyl). Optoelectrochemical experiments revealed that the nature of the substitution on the polymers had little effect on the extent of conjugation of the backbone as evidenced by electronic band gaps for all polymers of approximately 1.7 eV (730 nm). These electrochromic polymers switch from a relatively transmissive light green in the oxidized form to an opaque dark blue in the reduced form, with the highest electrochromic contrast ratios accessible for PBuDOT and PEDOT-C 14 H 29 . Multiple switching studies monitoring the electrochromic contrast showed that ca. 300 nm thick polymer films could be fully switched between their reduced and oxidized forms in 0.8-2.2 s with ∆%T of 44-63%. In situ conductivity studies carried out on relatively thick polymer films (2.7-9.5 µm) deposited between large gap (200 µm) lateral growth electrodes demonstrated the lowpotential turn-on for these materials, and maximum conductivities of 0.2-12.1 S/cm were attained.

Electrochromics (ECs) are materials that exhibit varying colors when held at various potentials. [1] In order to be useful for applications, these materials must exhibit long-term stability, rapid redox switching, and large changes in transmittance between states (large D%T values). Many inorganic materials have been used as EC materials, but difficulties in processing and slow response times have created the need for different types of EC materials. Conjugated, redox-active polymers offer a different approach to EC materials. [1] These polymers are inherently electrochromic, and they can be switched electrochemically or chemically between different colored states. [2] Most of the well-studied conjugated polymers are anodically coloring, meaning they are more deeply colored in their oxidized form. Poly(thiophene) (PT) and its 3-substituted derivatives fall into this category. These polymers are red to purple in their reduced or neutral form, and dark blue to black in their oxidized form. Although this type of color change can be useful, a more desirable color change would be one where the polymer switches from a highly colored state to a highly transmissive state.Of the conducting polymers available, poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives exhibit the most promising EC properties. When compared to PT, PEDOT exhibits more rapid switching, lower oxidation potentials, and greater stability at ambient and elevated temperatures. [3,4] In addition, PEDOT is a cathodically coloring polymer that is a dark opaque blue in its reduced form, and a very transmissive light blue in its oxidized form. [5±7] In our laboratory, we have successfully exploited the advantages of EDOT to synthesize many EC polymers. [8±10] We have shown that PEDOT can be used as a cathodically coloring polymer in dual-polymer EC devices with a D%T of 45 % at 620 nm. [11] Although other laboratories have studied PEDOT and other alkylenedioxythiophene derivatives, [7,12] our laboratory recently published the first exhaustive study of electrical, optical, and conductive properties of a large series of alkylenedioxythiophene derivatives. [13] We found that the D%T value of PEDOT can be improved significantly by increasing the alkylenedioxythiophene ring size or by incorporating substituents.Of the derivatives synthesized, poly(3,4-propylenedioxythiophene) (PProDOT) exhibited the greatest maximum in-situ conductivity, and because of its structure, it can be symmetrically disubstituted on the central carbon of the propylene bridge. [13] Our previous synthetic route did not allow for this disubstitution, but now we report the first disubstituted derivative, PProDOT±Me 2 . PProDOT±Me 2 exhibits an extremely high D%T value of 78 % at l max (578 nm), in fact the highest reported to date. We report here its optical properties, and compare them to PProDOT and the mono-substituted derivative, PProDOT±Me.The monomer synthesis is shown in Schemes 1a and 1b. ProDOT and ProDOT±Me were synthesized using the route illustrated in Scheme 1a, with ...

The preparation of a commercially acceptable plastic photochromic ophthalmic lens requires the incorporation of a number of properties -a neutral activated color, reasonable activation and fade rates, good lifetime, etc.. In this paper we will concentrate on approaches to finding photochromic systems with relatively neutral colors and acceptable rates of activation and fade.While offering good photochromic properties with regard to kinetics and photostability, they suffer from the fact that the visible absorption bands of the activated, or open, forms have narrow band widths. Also, without difficult to achieve substitution patterns, the absorption bands appear within a relatively narrow range of wavelengths. Partial neutralization of the activated color of the naphthoxazines was achieved through the use of indolino spirobenzoxazines. The open forms within this family exhibited broad absorption bands but the photochromic activity of each of the members was moderate to low. Enhancement of the photochromic activity was possible with triplet sensitization but at the expense of reduced lifetime. True color neutralization was achieved by coupling pyridobenzoxazines with members of a completely different family of photochromic compounds, the naphtliopyrans.The indolino spironaphthoxazines and related compounds have been known for over 25 years.

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