Synthesis and potency of long end-associative polymers for mist control

Long linear 1, 4-polybutadienes end-functionalized with associative groups were studied as additives to hydrocarbon fluids to mitigate the fire hazard of their mist in crash scenarios. These polymers were molecularly designed to overcome both the shear-degrdn. of long polymer chains in turbulent flows, and the chain collapse induced by the random placement of associative groups along polymer backbones. Linear polymers with discrete nos. of carboxyl groups on chain ends were investigated first: an innovative synthetic strategy was devised to achieve unprecedented backbone lengths and precise control of the no. of carboxyl groups on chain ends (N). A very narrow range of N was found to allow both sufficient end-assocn. strength and polymer soly. in apolar media. Shear rheol. revealed the end-assocn. of very long chains in apolar media leads to the formation of flower-like micelles interconnected by bridging chains. The polymer with N = 4 and Mw= 430 kg/mol was found shear-resistant, effective in providing fire protection to jet fuel at concns. as low as 0.3wt%, well-sol. in jet fuel ranging from -30 to +70°C, and showing little interference with dewatering. Four pairs of complementary associative end-groups of varying strengths were also investigated, in the hope of achieving supramols. with both mist-control ability and better utilization of polymer building blocks. Shear rheol. revealed the strength of complementary end-assocn. required to achieve supramols. capable of modulating soln. rheol. properties