The confinement of crystallizable blocks within AB or ABC microphase-separated block copolymers in the nanoscopic scale can be tailored by adequate choice of composition, molecular weight, and chemical structure. In this work we have examined the crystallization behavior of a series of AB and ABC block copolymers incorporating one or two of the following crystallizable blocks:  polyethylene, poly(ε-caprolactone), and poly(ethylene oxide). The density of confined microdomain structures (MD) within block copolymers of specific compositions, in cases where the MD are dispersed as spheres, cylinders, or any other isolated morphology, is much higher than the number of heterogeneities available in each crystallizable block. Therefore, fractionated crystallization takes place with one or several crystallization steps at decreasing temperatures. In specific cases, the clear observation of exclusive crystallization from homogeneous nuclei was obtained. The results show that, regardless of the specific morphological features of the MD, it is their vast number as compared to the number of heterogeneities present in the system that determines the fractionated character of the crystallization or in extreme cases homogeneous nucleation. The self-nucleation behavior was also found to depend on the composition of the copolymers. When the crystallizable block is confined into spheres or cylinders and exhibits homogeneous nucleation, the self-nucleation domain disappears. This is a direct consequence of the extremely high density of microdomain structures that need to be self-seeded (on the order of 1015−1016/cm3). Therefore, to increase the density of self-nuclei, the self-nucleation temperature has to be decreased to values so low that extensive partial melting is achieved, and some of the unmelted crystal fragments can be annealed, in some cases even before self-nucleation takes place.

Cross-linked N-isopropylacrylamide (NIPAAm) gel is covalently attached to a substrate, and the resulting interface is probed using surface plasmon resonance (SPR) as a function of hydrostatic pressure and temperature. SPR provides a direct measurement of the local refractive index, which changes with the swelling ratio of the gel film. Similar to bulk NIPAAm gel, the transition temperature increases and the volume phase transition becomes broader as pressure increases. The width of the transition ranges from less than 0.5 °C at 1 bar to as much as 10 °C at 1000 bar, and the transition temperature increases by as much as 7 °C over the same range of pressures. However, the presence of a fixed substrate effectively confines the volume phase transition near the interface to one dimension, perpendicular to the substrate. This has significant effects on the transition temperature, particularly at high cross-linking density and high concentration of an ionizable comonomer. Furthermore, the swelling effect of the ionic groups is reduced, and the water content of the swollen gel does not change with increased ionic content. While the volume phase transition of the corresponding bulk gels can have a total volume change as large as 100-fold, the gel films have a total volume change around 15-fold.

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