Acceleration of the densification of a silica sol–gel by inclusion of generation-zero poly(amidoamine) dendrimer

Sol–gels were formed from tetramethoxysilane (TMOS) precursors at ca. pH 1 in the presence and absence of generation-zero poly(amidoamine) dendrimers (G0-PAMAM). To test the hypothesis that G0-PAMAM serves as a crosslinking agent, the pore structure was investigated over a 52-week period with the premise that crosslinking will be accompanied by more rapid densification that when this agent is absent. In agreement with the hypothesis, nitrogen adsorption data stabilized after 25 weeks when G0-PAMAM was present, whereas in its absence, the total pore volume continued to decrease over the entire period. In both cases, the sol–gels were aged at ambient laboratory temperature in a controlled environment with 9% humidity.