Trifunctional methyltrimethoxysilane and bifunctional dimethyldimethox
ysilane monomers were cocondensed in water in the presence of surfacta
nt. Strictly spherical micronetworks of narrow size distribution were
obtained for particle sizes 10 nm < R < 30 nm. By special ''endcapping
'' reactions all reactive SiOH groups were removed quantitatively, and
the resulting micronetworks become soluble in common organic solvents
like toluene, THF, or chloroform. For contents of trifunctional monom
er larger than 50 mol % the particles do not swell irrespective of the
choice of the solvent, whereas for lower mole fractions of trimethoxy
silane an increasing swelling ratio is observed. Below 2.5 mol % trifu
nctional monomer the reaction within a microparticle remains subcritic
al and nonspherical, branched molecules are obtained. Subsequent addit
ion of the bi- and trifunctional units leads to a micronetwork topolog
y with different physical properties as compared to the simultaneously
cocondensed one at identical overall particle composition. For instan
ce, at 57 mol % trifunctional monomer content the ''homogeneously'' cr
oss-linked microgel exhibits no glass transition before decomposition
whereas the core-shell particle with linear chains in the core shows a
weak glass transition at T-g = -107 degrees C.