Multifunctional initiator for obtaining star-shaped polymers by an anionic route, process for its manufacture and corresponding star-shaped polymers, process for their manufacture and their applications

A multifunctional anionic polymerization initiator which is in the form of a star-shaped polymer and is soluble in an apolar medium, said initiator being denoted by the formula (I):

• (PA).sub.a N.sup.n- nLi.sup.+ (I)
• in which:
• PA denotes a polymer block originating from at least one monomer A chosen from vinylaromatic or diene monomers;
• a denotes the number of arms of the PA block and is between 3 and 15;
• N denotes a crosslinked core substantially free of residual double bonds, which has the formula:
• (PMc)(RLi).sub.p
• in which:
• Mc is a monomer containing at least two polymerizable double bonds per molecule;
• PMc is a core comprising a crosslinked polymerized monomer Mc, and containing 3 to 30% of residual double bonds in relation to the initial double bonds originating from the monomer Mc;
• R is an alkyl radical with a linear or branched chain having 1 to 6 carbon atoms, an aryl radical with one or a number of ring(s), an arylalkyl or alkylaryl radical in which the alkyl group has from 1 to 6 carbon atoms, a cycloalkyl radical and a C.sub.2 -C.sub.6 alkenyl radical substituted by an aryl or alkylaryl group;
• and
• p is the number of anionic sites resulting from the neutralization of the residual double bonds in PMc by RLi;
• and
• n is the number of anionic sites present in the crosslinked core N;
• n is equal to a'+p or to p, p having the above meaning and a' being the number of anionic sites present in the crosslinked PMc core and corresponding to the number (a) of arms of the PA block.