Thermo-Reversible Gelation Of Rod-Coil and Coil-Rod-Coil Molecules Based on Perylene Diimides

Polymer gelation is a route to obtain highly organized morphologies. The aim of my thesis was to study the physical gelation of covalently attached perylene diimide (PDI) polymers during their self-assembly. With the gelators used, chain entanglement and network formation trap the solvent causing gelation. Hence, forces such as hydrogen bonding are not a requirement. We first describe the thermo-reversible gelation of PDMS via the physical route, without any functionalization. We discuss a solvent system, propylamine or hexylamine, gelled by PDMS, without any filler, catalysts or chemical crosslinks. The simple route to the physical gelation of PDMS was then extended to preparing PDMS attached PDI based gels. We then continued our work with PDI attached to a water-soluble side chain; here we studied the gelation of PDI, substituted with Jeffamine® on one imide nitrogen (MJ-PTCDI) or both (DJ-PTCDI). Previous studies in our group showed that self-assembly of the PDI was seen in water and aqueous solvent mixtures, but not in the other non-aqueous solvents. In the present case, the morphology of the gels depended on the amount of solvent: non-solvent ratio. For our final gelator, we attached oligostyrene to both sides of the PDI (PS-PTCDI-PS), to form a coil-rod-coil molecule, and studied its gelation behavior. This differs from the case of coil-rod-coil molecules discussed before; with Di-PDMS, the Tg of the PDMS segment is -125 °C. With DJ-PTCDI, considering that the glass transition temperatures of PEO and PPO are -50 and -75 °C, respectively, the Tg of Jeffamine® can be expected to be about -60 °C. However, here the oligostyrene segment has a Tg of 43 ˚C. We finally used the PS-PTCDI-PS as a guest in its corresponding polystyrene (PS) polymer matrix, in an attempt to make composite films. We showed that by attaching a side group (oligostyrene) which is compatible with the PS polymer, the mixing would be better. Hence, molecularly dispersed composite film could be obtained. The aim was to fabricate films with no crystallization or phase separation. Further research on these composite polymer films will shed light on their outstanding optical properties.