Polymer composites reinforced by hydrophilic clay aerogels were produced and found to possess interpenetrating cocontinuous structures, not the exfoliated structure often observed in clay nanocomposites. An efficient process for producing these clay aerogels was recently reported; in-situ polymerization of N-isopropylacrylamide within the clay aerogels was readily accomplished. The resulting composites have low densities, are stable, and exhibit a new synergistic effect of interpenetrating organic-inorganic phases in which the organic polymer prevents loss of aerogel structure in water by encapsulation, while the inorganic filler increases the structural integrity of the polymer. The composites undergo phase transition and show LCST behavior similar to unmodified poly(N-isopropylacrylamide) despite the presence of reinforcing clay aerogels. Reversible changes in morphology of the aerogel hydrogel composites are observed with varying degrees of hydration.