New Low Band Gap Polymers: Control of Optical and Electronic Properties in near Infrared Absorbing π-Conjugated Polysquaraines

A novel approach to design extremely low band gap polysquaraines with intense near-infrared (NIR) absorption and high intrinsic conductivity is described. Feasibility of the new strategy is illustrated by an A-B type copolymerization of squaric acid and 1,4-dialkoxydivinylbenzene-bridged bispyrroles, which resulted in zwitterionic polysquaraines with resonance stabilized quinoid structures. Incorporation of an electron donating conjugated moiety between each squaraine dye repeating unit has a dramatic influence on the optical and electronic properties of the resulting polysquaraines due to an enhanced donor−acceptor−donor interaction. The solution UV−Vis−NIR absorption maxima of the new polymers, between 772 and 1040 nm with ground-state onset absorptions ranging from 1140 to 1300 nm, is unusual for conjugated polymers and is a signature of their low band gaps. The band gaps of these polymers are around 1 eV with the lowest value of 0.79 eV for 6a. The intrinsic conductivities of these polymers could be modulated between 10-7−10-4 S/cm by varying the length of the alkyl side chains. This is in agreement with the molecular packing data obtained from the X-ray analysis that revealed an interdigitated arrangement of the polymer chains. The solubility inducing alkyl side chains play a decisive role in the molecular packing, which control the optical band gap and conductivity of the reported polysquaraines. This is one of the simplest strategies for the synthesis of NIR absorbing conjugated polymers with extremely low band gaps that are soluble and intrinsically semiconducting

First Phenylenevinylene Based Organogels: Self-Assembled Nanostructures via Cooperative Hydrogen Bonding and π-Stacking

First Phenylenevinylene Based Organogels:  Self-Assembled Nanostructures via Cooperative Hydrogen Bonding and π-Stackin

Zwitterionic Dye-Based Conducting Polymers. Synthesis and Optical Properties of Pyrrole-Derived Polysquaraines

Zwitterionic Dye-Based Conducting Polymers. Synthesis and Optical Properties of Pyrrole-Derived Polysquaraine

Hybrid Thermoreversible Gels from Covalent Polymers and Organogels

This paper reports on experiments intended for investigating the feasibility of preparing hybrid thermoreversible gels from covalent polymers and noncovalent self-assembling π-conjugated molecules. The formation and the degree of dispersion of these hybrid gels have been studied with polystyrenes of various tacticities and oligo(p-phenylenevinylene) molecules (OPV) in different nonpolar organic solvents. Detailed investigations of the systems have been carried out by DSC, SAXS, and AFM. It is shown that no liquid−liquid phase separation is involved, indicating that the systems are highly compatible, and that the growth of one type of gel does not interfere with the other. These studies reveal that the resultant hybrid gels are composed of the intermingled fibrillar architectures of both gels