We propose a combination of polymer field theory and off-lattice computer simulations to study polymer-bridged gelation in polymer-nanoparticle mixtures. We use this method to study the structure of gels formed in attractive polymer-colloid systems. Our results indicate that such gels exhibit a universal structure with a fractal dimension $d_f\approx 2.5$ characteristic of random percolation. By mapping to an affine-network model, the enhancement in elastic moduli is predicted to follow a critical exponent ${\nu }_{\eta }\simeq 1.8$ characteristic of the resistor network percolation. We analyze selected experimental results to suggest the existence of a universality class corresponding to our results.

• Received 30 January 2006

DOI:https://doi.org/10.1103/PhysRevLett.96.177805