Controlled Synthesis of Novel Metalated Poly(aminohexyl)-(aminopropyl)silsesquioxane Colloids

A new family of polysilsesquioxanes colloids was synthesized by hydrolytic condensation of a functionalized precursor N-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS), H 2 N(CH 2 ) 6 NHCH 2 CH 2 CH 2 Si(OCH 3 ) 3, and studied using small-angle X-ray scattering, transmission electron microscopy, liquid and solid state NMR, elemental analysis, and other methods. The PAHAPS (polymerized AHAPS) structure is highly functionalized and its functionality can be varied by protonation of the amino groups. This allows varying the local ordering in the PAHAPS colloids, including formation of highly ordered lamellar structures when the AHAPS precursor is hydrolyzed in pure water. By varying the type of solvent (water or THF), one can vary the macrostructure and properties (for example, to impart colloidal solubility) of PAHAPS. These features make PAHAPS a robust polymer material synthesized in a one-pot reaction procedure. As amino groups (protonated or not) easily interact with the majority of transition-metal compounds, PAHAPS colloids can template a variety of particles of interest: magnetic, semiconductor, metal, or metal oxides with a small variation in the synthetic procedure. Here, formation of narrowly distributed discrete Pt nanoparticles packed within PAHAPS colloids (Pt content reaching 36 wt % without particle agglomeration) is described. The dependence of Pt nanoparticle and PAHAPS colloid sizes on metal compound and reducing agent types is demonstrated.