Cocrystallization of a poly(ethylene-butene) random copolymer with C-24 in n-decane

摘要

Amorphous-crystalline random copolymers containing ethylene and butene (PEB) segments are known to self-assemble in solution to yield one-dimensional micellar structures, i.e., rodlike aggregates. This behavior stands in contrast with the amorphous-crystalline diblock polymers, where self-assembly leads to a core consisting of a rough textured plate of polyethylene cloaked by the amorphous component; either alternating polyethylene-propylene) or random polyethylene-butene). These materials serve as nucleation platforms for wax crystal size control in commercial formulations for middle distillate fuels. Here, we present small-angle neutron-scattering results to evaluate the influence of C-24 wax in the presence of the PEB random copolymer upon the self-assembly event. In stark contrast to the rodlike micelles the random copolymers cocrystallize with the wax in thin sheets consisting of a single paraffin layer surrounded by amorphous polymer hairs on both plate sides. Such structures have not been seen before. The polymer brush is well-defined, indicating a homogeneous distribution of the polymer in the wax-stabilized plate. It can be conjectured that this behavior may prove to be a viable mechanism regarding the development of flow improvers for waxy crude stocks. [References: 9]