  We have investigated PLLA crystallization in lamellae-forming PS-b-PLLA
confined to straight cylindrical nanopores under weak confinement (nanopore
diameter D / equilibrium PS-b-PLLA period L0 larger than 4.8). Molten PS-b-PLLA
predominantly forms concentric lamellae along the nanopores, but intertwined
helices occur even for D/L0 = 7.3. Quenching PS-b-PLLA melts below TG(PS)
results in PLLA cold crystallization strictly confined by the vitrified PS
domains. Above TG(PS), PLLA crystallization is templated by the PS-b-PLLA melt
domain structure in the nanopore centers, while adsorption on the nanopore
walls stabilizes the outermost cylindrical PS-b-PLLA shell. In between, the
nanoscopic PS-b-PLLA melt domain structure apparently ripens to reduce
frustrations transmitted from the outermost immobilized PS-b-PLLA layer. The
onset of PLLA crystallization catalyzes the ripening while transient ripening
states are arrested by advancing PLLA crystallization. Certain helical
structure motifs persist PLLA crystallization even if PS is soft. The direction
of fastest PLLA crystal growth is preferentially aligned with the nanopore axes
to the same degree as for PLLA homopolymer, independent of whether PS is
vitreous or soft.
