The concept of polymerization-induced phase separation with hydrogen-bonded supramolecular polymers was investigated by the photopolymerization of films containing mixtures of supramolecular polymer 1a or 1b and varying amounts of monoacrylate and diacrylate with UV-A (320-400 nm) radiation (5 W/cm(2)) for 0.3 s. The extent of the phase separation after photopolymerization was determined by differential scanning calorimetry and scanning electron microscopy, which showed that film 1 containing no diacrylate is macrophase-separated, while films 2 and 3 containing 17.0 or 42.5% diacrylate are microphase-separated. Increasing the amount of diacrylates has a strong influence on the morphology development, as it decreases the length scale of the phase separation by shortening the time available before vitrification sets in-in this way decreasing the crystallinity of the supramolecular phase. Tensile tests and DMTA measurements showed that the mechanical properties of the films containing the hydrogen-bonded supramolecular polymers are comparable to those films containing covalent high molecular weight polymers.