New amphiphilic networks have been synthesized by free-radical copolymerization of hydrophobic methacryloyl capped polyisobutylenes (MA-PIB-MA) with hydrophilic 2-(dimethylamino)ethyl methacrylate (DMAEMA). Two MA-PIB-MAs have been prepared with M.sub.n =4920 and 10,200, and two series of networks were prepared with MA-PIB-MA contents between 48% and 71.5%. Variation of the molecular weight of MA-PIB-MA and its concentration in the network allows for a wide range of mechanical properties and swellability in hydrophilic and hydrophobic solvents. Differential scanning calorimetry shows the existence of two glass transitions in these networks and thus indicates a phase-separated domain structure. Tensile strengths and elongations are dependent on MA-PIB-MA contents, varying from 57.7 kg/cm.sup.2 to 39.8 kg/cm.sub.2 and 168% to 200%, respectively, with increasing MA-PIB-MA content. Solvent swelling of the networks range from 170% to 20% in water and from 40% to 170% in n-heptane with increasing MA-PIB-MA contents.