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A large group of methods is based on the chemical bonding of the
functional prepolymers in which reactive groups - or terminal (such as a
hydroxyl group PEO) or distributed along the main chain of the prepolymer
(PVA). If the functionality of one of more than two prepolymers and functional
groups in two different types and prepolymers capable of chemical interaction,
then conetworks may be synthesized from prepolymer without - any further
binding agents. Example - the reaction between the bromine-containing butyl
rubber and PEO in toluene in the presence of a catalyst t - BuOK [78, 79]. The
resulting amphiphilic conetwork comprises two continuous phases. As evidence,
the authors indicate the ability of swelling the resulting material as a solvent for
the PEO (dioxane, tetrahydrofuran), and for butyl (cyclohexane).
If prepolymers have the same type of group, to form a reaction system
conetworks administered three low molecular weight component providing
chemical bonding two prepolymers. To obtain a crosslinked structure of
prepolymers or low molecular weight crosslinking agent must have a
functionality greater than two. In this way conetworks were synthesized from
linear and star-shaped PEO polyisobutylene with three terminal hydroxyl groups
when used as a crosslinker hexamethylene - diisocyanate [80, 81]. The reaction
is carried out in a common solvent for the two prepolymers - toluene. If one of
the hydroxyl-containing prepolymers is PVA, it is often for stitching and
receiving conetworks using glutaraldehyde [82].
To implement the optimum properties should be avoided conetworks macro
phase separation of components during synthesis. A common technique - the use
of a common solvent for both components. To a certain extent able to maintain
compatibility of the conversion of the reactants. After reaching a high
conversion system becomes thermodynamically incompatible. However, the
high viscosity of the reaction system and the degree of crosslinking prevent
macro phase separation. Several disadvantages arise from - the need to use large
amounts of solvent, which requires some effort to remove it from the reaction
system. The situation is improved if the synthesis conetworks of hydrophobic
and hydrophilic monomers, macromonomers of the solvent is replaced with
monomers that contribute to the reconciliation of the reactants. For example,
when receiving conetworks based siloxane macromonomers with (meth) acrylic
groups capable of polymerization and hydrophilic monomer (HEMA, VP, N, N -
dimethylacrylamide) monomers of the general formula are used:
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