Gc. Claudio et Er. Bittner, Random growth statistics of long-chain single molecule poly-(p-phenylene vinylene), J CHEM PHYS, 115(20), 2001, pp. 9585-9593
Structures of poly-(p-phenylene vinylene) (PPV) were generated using a rand
om growth algorithm. The algorithm assumes that the configuration of a part
of the polymer (a few monomers length) can be sampled from the configurati
on of a PPV trimer. The probabilities of the configurations of the trimer a
re taken as the Boltzmann weight of the energies. We constructed several ty
pes of polymers with different numbers of cis-defects which were added to t
he polymer either uniformly or randomly distributed within the entire polym
er. Polymer characteristics, such as conjugation length, end-to-end distanc
e, and radius of gyration, were also calculated. The trends of these charac
teristics were found to be inversely proportional with the number of cis-de
fects in the polymer. Although average conjugation lengths are generally in
dependent of the distribution of cis-defects, the morphology of the polymer
is dependent on cis-defect distribution. This suggests that conformational
disorder rather than cis-defect density is the determining factor in excit
on localization and diffusion in these systems. Finally, we derive a simple
model similar to the Ising model that relates the energy needed to break c
onjugation to the average conjugation length. (C) 2001 American Institute o
f Physics.