Investigation of the substitution effect on poly(bis-3,4-ethylenedioxythiophene methine)s through solid state polymerization

Abstract

Thieno[3,4-b]-1,4-dioxin, 5,5′-methylenebis[2,3-dihydro] was chosen as a universal solid state polymerization (SSP) platform due to its ready synthesis procedure, further tunable substitution groups on the CH₂ bridge and its excellent conjugated quinonoid structure of corresponding poly(bis-3,4-ethylenedioxythiophene methine). These monomers were designed by taking the steric effect and molecular flexibility into consideration and by careful investigation under SSP. In addition, the aromatic moieties were firstly introduced in the branch chain in this polymer matrix, which may offer amazing properties and further modification opportunities based on this unique platform. Our results reveal that the substitution groups on the CH₂ bridge play an important role in SSP. The bulkier the substitution group and the longer effective halogen distance the monomers have, the higher onset temperature (T_onset) the SSP will have. Furthermore, the primitive dependence of T_onset with an effective halogen distance was established.