Distribution of Conjugation Lengths in an Ensemble of Lattice Polymers

Abstract

The distribution of segment sizes, that is, the average and dispersion of the number of segments of a given size per chain, is investigated in an ensemble of lattice polymers. This distribution is the lattice version of the conjugation length distribution of conjugated polymers, which is central for both electronic and photophysical properties of conjugated polymer materials. Clear evidence is found that, when the chains interact only via excluded volume, both the average and the dispersion depend exponentially on the segment size and, at least for the more prevalent segment sizes, are identical to what is found in an isolated self‐avoiding chain. Whereas the polymer concentration has a clear effect on the end‐to‐end distances of the chains, it does not affect significantly the segment size distribution of the chains. It is argued that this happens whenever there is no distance or orientation correlation in the polymer distribution, that is, in a truly amorphous system, but not in the presence of aggregates or nematic order.

The Polymerization of Homogentisic Acid In Vitro as a Model for Pyomelanin Formation

“…This may be related to the extended conjugation length of the different polymers. [51] In general, the EPR peak shape and width were similar to those of eume- lanins and consistent with the pyomelanin spectra reported in the literature. [52] A close inspection of the EPR peak of polyHGA showed a noticeable asymmetry.…”

“…However, the polyHGAs generated in the presence of laccase at pH 7.4 or peroxidase at either pH 5 or pH 7.4 were measurably conductive (Figure 9), with average log 10 G values of −11.52 ± 0.28, −8.52 ± 0.24, or −9.30 ± 0.32 S, respectively (I-V curves are in Figures S31-S36 in the Supporting Information), and a comparison of log G counter maps is shown in Figure S37 (Supporting Information); i.e., conductivity (G) of 2.9 × 10 -3 ± 1.1 × 10 -3 , 0.58 ± 0.2, or 3.4 ± 1.2 nS, respectively. The differences in the electronic properties of the polymers [51,57] are likely to be related to the extended conjugation length of the poly-HGAs produced by laccase-/peroxidase-mediated polymerization of HGA, supported by the greater amounts of polyHGAs produced by laccase-/peroxidase-mediated polymerization of HGA and by EPR data (Figure 7). The polyHGAs produced have potential for application as green/sustainable [58] and components of electronic devices, [27,[59][60][61][62][63][64] or other high value added applications (particularly after optimization of the synthesis).…”