The most attractive property of amphiphilic polymer conetworks (APCNs) is their ability to swell in both polar and nonpolar solvents. Depending on the composition, their structure is phase separated on the nanometer scale possessing highly different morphologies. This special nanophase-separated structure provides numerous possible applications for heterogeneous chemical and biological processes. Although the interphase region can fundamentally influence the material transport between the different polarity phases, there has been no specific information regarding its nature. Recent work demonstrates that by selective labeling of the cross-linking molecules by deuterium, information on the mobility of the interphase region can be obtained by solid-state NMR techniques. The first results show that this interphase region behaves differently in dry state as well as when swollen in polar or nonpolar solvents. Although the cross-linker is a polar molecule, its mobility hardly changes upon swelling in water; however, its mobility increases drastically by swelling in heptane. Additionally, the amount of nonreacted, thus. non-cross-linked, chain ends could be quantified by solid-state NMR methodologies.