Organic-Inorganic Telechelic Polymers

The formation of telechelic materials is an alternate method to have covalent bonding between the organic and the inorganic phase of the composite material. A telechelic polymer is one containing one or more functional end groups (See Figure 1) that have the capacity for selective reaction to form bonds with another molecule. 1

Figure 1: Telechelic Polymers

Telechelic polymers typically contain hydroxyl or carboxylic acid endgroups. Composite materials or block copolymers can then be made through these endgroups by post-reactions. A polymerization could be started off of the -OH or -COOH endgroups or by changing the endgroup functionality, the -OH or -COOH endgroup to form a vinyl endgroup, a free-radical reaction could occur.

Organic-inorganic telechelic polymers can be made through two methods: condensation reactions or condensation/hydrosilylation reactions. In the first method, a condensation reaction can be done utilizing an ORMOSIL monomer that contains such functionalities as an amine, epoxy, or cyano. Typically, little or no catalyst is needed for these condensation reactions to occur. In the second two-step method, the -OH or -COOH endgroups are first endcapped with vinyl groups via a condensation reaction with, for example, acrylic acid for a hydroxyl endgroup. Then in a second step, a hydrosilylation reaction is done utilizing the telechelic vinyl-endcapped polymer and a silane monomer. Here a catalyst is needed. However, the catalyst used is dependent upon the polymer backbone. Certain catalysts used can add at a carbonyl instead of at a vinyl, therefore, catalyst choice is critical.

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Written by: Sandra Young (Partially From Her Research Prospectus)

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