Can short alkyl chain fold in lamellar crystals?*

By coupling a hydroxyl-terminated polyethylene-\textit{block-} poly(ethylene oxide) (PE-$b$-PEO or EEO) diblock oligomer and isocyanatopropyldimethylsilylcyclopentyl-polyhedral oligomeric silsesquioxane (CP-POSS), an asymmetric ABC coil-coil-sphere triblock oligomer was successfully synthesized. The structure and morphology of the supramolecular self-assembly in bulk EEO-POSS was studied by differential scanning calorimetry (DSC), synchrotron small- and wide-angle X- ray scatterings (SAXS and WAXD) and transmission electron microscopy. The melting temperature of the POSS in triblock copolymer was at ca.156\r{ }C as determined by DSC. The POSS crystallized into ABCA four-layer trigonal structure and sandwiched between the amorphous EEO layers. Below 100\r{ }C the PE block crystallized into two types of crystals, namely, extended and once-folded chain crystals with overall d-spacing of 14.0nm and 10.9nm, respectively. During a cooling process, the once folded-chain grew first and then extended chain grew at higher supercoolings. In a heating process, extended chain first melted and once folded chain disappeared at higher temperature.