SWITCHING SUPRAMOLECULAR POLYMERIC MATERIALS WITH MULTIPLE LENGTH SCALES

It was demonstrated that polymeric supramolecular nanostructures with several length scales allow straightforward tailoring of hierarchical order-disorder and order-order transitions and the concurrent switchin g of functional properties. Poly(4-vinyl pyridine) (P4VP) was stoichio metrically protonated with methane sulfonic acid (MSA) to form P4VP(MS A)(1.0), which was then hydrogen-bonded to pentadecylphenol. Microphas e separation, re-entrant closed-loop macrophase separation, and high-t emperature macrophase separation were observed. When MSA and pentadecy lphenol were complexed to the P4VP block of a microphase-separated dib lock copolymer poly[styrene-block(4-vinyl pyridine)], self-organized s tructures-in-structures were obtained whose hierarchical phase transit ions can be controlled systematically. This microstructural control on two different length scales (in the present case, at 48 and 350 angst roms) was then used to introduce temperature-dependent transitions in electrical conductivity.