Insight into the gelation habit of oligo(para-phenylene vinylene) derivatives: effect of end-groups

This paper reports a study on the gelation habits of organogels prepared in benzyl alcohol from derivatives of oligo(p-phenylene vinylene) (OPV) bearing C16H33 aliphatic wings and a series of end groups on the backbone. Significant differences are observed based on whether or not these end groups can establish hydrogen bonds with adjacent OPV molecules or with the solvent. It is particularly shown that the fibril structure, the morphology and the molecular organization not only depend upon the aliphatic wings and/or the pi-pi interactions of the backbones but equally on the nature of these end groups. Evidence highlighting a homogeneous nucleation process for gel formation are also presented and discussed. Discrepancies with thermoreversible gels of covalent polymers are also stressed.