CONTEXT

Most of  existing living  free-radical polymerization techniques concern organic(co)polymers. The synthesis of organic-mineral block copolymers have sometimes been described but  with these  techniques the nature of organic blocks are limited and they do not give access to blocks of well-controlled length and narrow molecular distribution

This invention presents a novel process of synthesis of  organic-mineral block copolymers easy to implement and without the drawbacks of the previous techniques.

TECHNICAL DESCRIPTION

The invention concerns a novel thermal controlled free-radical polymerization process that gives access to copolymers of silicone and organic nature, consisting of a silicone skeleton onto which are grafted organic groups in block or multiblock form. They are prepared from a silicone precursor, at least one organic ethylenically unsaturated monomer and a free-radical polymerization initiator.

The invention concerns a method for preparing by thermal activation of hybrid silicone and organic polymers comprising the motifs

RxUySiO[4-(x+y)]/2

wherein:

x is equal to 0, 1, 2 or 3,
y is equal to 0, 1, 2 or 3 with 2<=(x+y)<=3 and
y is different from 0 for at least one of the hybrid copolymer motifs;
and the symbols U, identical or different, represent organic polymer units.

The invention also relates to the hybrid copolymers that may be obtained by this new process and to the precursor silicones, which are used for the preparation of the hybrid copolymers.

BENEFITS

This novel route of synthesis presents the following main advantages:
– do not require the use of a source of UV irradiation which is difficult to implement industrially;
– allows the synthesis of silicone and organic hybrid copolymers whose polymerized organic monomers are of very varied nature;
– allows a controlled free-radical polymerization method for the synthesis of silicone and organic copolymers comprising no metallic impurities that are harmful to their use;
– allows to obtain organic blocks of controlled lengths and organic blocks of narrow molecular distribution;
–   may be implemented in solution, in bulk, in dispersion, in suspension or in emulsion.

INDUSTRIAL APPLICATIONS

All fields of application of silicones

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