Chemistry Reference
In-Depth Information
Fig. 7.3
The structure of
tetrakis(2-hydroxyethyl)
orthosilicate (THEOS)
OH
H
OO
Si
O
O
OH
H
Fig. 7.4
Amine and epoxide
silicate colloids forming an
organosilicate material
Fig. 7.5
Epoxy-amino sili-
cate starch interpenetrating
network
reproducible manner followed by formulation of the biohybrid composite where the
effect of the degree of interaction between the two components can be investigated.
A demonstration of this approach is our synthesis of a series of biohybrid silicate
materials as illustrated in Fig.
7.3
through Fig.
7.6
. We selected a silicate material
made from two different silicate nanoparticles. This allowed us to generate two or-
ganosilicate reaction mixtures containing epoxide decorated silicate nanoparticles
(TG) and amine decorated silicate nanoparticles (AT). Individually, these silicate
nanoparticles are stable in aqueous solution over a period of weeks. However, when
combined, they undergo rapid epoxy-amine crosslinking to form a glassy material
in approximately 30 min. These interactions are shown schematically in Fig.
7.4
.
To these epoxy and amine decorated preformed silicates, we have added starch
with and without amine functionalization. In the absence of an amine function-
alization of the starch, the use of a 1-3 % solution of starch in water results in a
readily formed interpenetrating network with the silicate network and the starch
as preformed, solution borne polymers. The solidification of the biohybrid mate-
rial occurs due to the rapid epoxy-amine crosslinking of the silicate. This is shown
schematically in Fig.
7.5
. The physical, optical and mechanical properties of these
hybrids are significantly different from those observed for the starch free materials
even for materials made with 1 % solutions of starch.
The range of properties for biohybrids constructed based on these silicate start-
ing materials have been further extended by using a biopolymer that will interact
covalently with the epoxy or amine decorated silicates. This can be done readily by
