I would not say that a special part of the triblock copolymer accounts for the sol-gel formation of gels. Triblock copolymers are used for producing micelles around which structured gel can be formed. After removal of the triblock copolymer, voids remain, hence the porosity (most of times ordered, because of the self-organisation of micelles with respect to each others). So all parts of the triblock copolymers are necessary, otherwise no micelles can be formed. As most gels are formed in polar solvents, the hydophylic heads of the triblock copolymers are in contact with the gel, maybe this was your question.

Alain

Dear Alian highly thankful for your nice suggestions