Process for the preparation of a vinylidene chloride polymer composite

A process for preparing a vinylidene chloride polymer composite, the process comprising:

• providing a dispersion of a solid particulate material in a liquid phase, said dispersion comprising a RAFT/MADIX agent of formula (III):
• wherein
• Ra is selected from C1-C6 alkyl, C1-C6 alkoxy, aryl and heteroaryl, each of which may be substituted with one or more hydrophilic groups selected from —CO2H, —CO2R, —CN, —SO3H, —OSO3H, —SOR, —SO2R, —OP(OH)2, —P(OH)2, —PO(OH)2, —OH, —OR, —(OCH2—CHR0)w—OH, —(OCH2—CHR0)w—OR, —CONH2, CONHR1, CONR1R2, —NR1R2, and —NR1R2R3;
• R1, R2 and R3 are independently selected from C1-C6 alkyl and aryl which are optionally substituted with one or more hydrophilic substituents selected from —CO2H, —SO3H, —OSO3H, —OH, —(OCH2CHR0)w—OH, —CONH2, —SOR, SO2R, and salts thereof;
• R is C1-C6 alkyl;
• R0 is selected from hydrogen and R:
• w is an integer from 1 to 10;
• Z is selected from optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [—P(═O)(OR4)2], and dialkyl- or diaryl-phosphinyl [—P(═O)R42];
• R4 is selected from the group consisting of optionally substituted C1-C18 alkyl, optionally substituted C2-C18 alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted alkylaryl, optionally substituted acylamino, optionally substituted acylimino, optionally substituted amino, and a polymer chain formed by any mechanism;
• each H is independently a polymerised residue of an ethylenically unsaturated monomer;
• and
• n is an integer from 1 to 300;
• providing vinylidene chloride and optionally at least one ethylenically unsaturated monomer copolymerisable therewith to said dispersion;
• and
• polymerising vinylidene chloride and optionally said at least one ethylenically unsaturated monomer under the control of said RAFT/MADIX agent to form vinylidene chloride polymer at the surface of said solid particulate material.