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Dendritic, Nanosized Building Block for Siloxane‐Based Materials: A Spherosilicate Dendrimer
Author(s) -
Kawahara Kazufumi,
Hagiwara Yoshiaki,
Kuroda Kazuyuki
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102205
Subject(s) - dendrimer , hydrosilylation , siloxane , silylation , reagent , allylic rearrangement , materials science , chemical engineering , nanoparticle , ether , polymer chemistry , surface modification , chemistry , organic chemistry , nanotechnology , catalysis , polymer , engineering
Abstract A spherosilicate dendrimer ( DMS‐1 ) with closely spaced reaction sites (SiH groups) on the dendrimer surface has been synthesized by stepwise silylation of double‐four‐ring silicate with chlorotriethoxysilane (ClSi(OEt) 3 ) and subsequently with chlorodimethylsilane (ClSiHMe 2 ). DMS‐1 consists of a maximum of 40 Si atoms in the interior frameworks and 24 reactive SiH groups on the surface. Because DMS‐1 is spherical and about 1.5 nm in diameter, it can be regarded as the smallest well‐defined silica‐based nanoparticle. DMS‐1 also forms molecular crystals and is soluble in typical organic solvents. A molecularly ordered silica‐based hybrid can be prepared by heating a cast film of DMS‐1 at 180 °C for 5 days. The surface of DMS‐1 can be modified by hydrosilylation with 1‐hexadecene, triethoxyvinylsilane, and allylic‐terminated tetraethylene glycol monomethyl ether. More than 20 SiH groups out of 24 react with these reagents. The solubilities of the products depend on the modification. DMS‐1 is not only a building block for nanohybrids, but also the smallest and most precisely designed siloxane‐based nanoparticle.