Mega-​supramolecules by end-​association of very long telechelics: Highly potent rheological modifiers and mist controllers

Abstract

To form mega linear supramols. by assocn. of telechelic polymers at concn. as low as possible, very long chain lengths are used; telechelic polymers with Mw>400 kg/mol were synthesized to mimic multimillion MW polymers as rheol. modifiers-and they did. Building on the Hilmyer-Macosco protocol for ROMP of cyclooctadiene with CTAs bearing end-groups, improvements in monomer purifn. enabled synthesis of telechelics with unprecedented length. Steady shear viscometry confirmed the dramatic enhancement in the rheol. effect brought by longer backbone length. And pairwise associative telechelics showed more potent rheol. consequences comparing to self-associative ones; esp. in mist-control effect. Mega-linear polymers (Mw > 1e6 g/mol) have been known for decades to suppress mist formation and improve fuel safety under severe impact (Figure 2a). However, their use is limited by "shear degrdn.," (Figure 2b). Long pairwise associative polymers are as effective as mega-linears-and have excellent shear resistance (Figure 2d). GPC-MALLS and SANS were performed to study the distributions and structures of supramols.