Geopolymers can be considered as a member of the family
of silicon based inorganic polymers.
The simplest member of the family is that described by sol-gel
silica technology (ref: Hench, L.L, "Sol-Gel Silica. Properties,
Processing and Technology Transfer," Noyes Publications,
1998), where silicon ions are dissolved from a pure silica
feedstock. The polymer chains so produced can be represented
by;
- Si - O - Si - O - Si -
The next most complex members are the geopolymers
where some Si ions in the chain or net are replaced by Al
ions, and represented by;
- Si - O - Si - O - Al(Na) - O - Si
- ect.
A more complex member of the family is commonly know as
Alkali-Activated Cement. Here Ca is introduced into the geopolymer
sol and the resultant hardened matrix consists of a mixture of
phases;-
- geopolymer phases represented by;
- Si - O - Si - O - Al(Ca/Na) - Si - O - Si
- and
- calcium silicate hydrate phases (CSH).
Research into heavy metal ion encapsulation suggests that other
metal ions can substitue into the chains or nets and that Fe
also appears to play an active role in the poymerization
process
It is postulated that there are other possible members
of the family (or another family) involving Zircon instead of
Silicon.
