Initiating process and system for the anionic polymerization of acrylic monomers

Initiating system for the anionic polymerization of acrylic monomers or the anionic copolymerization of acrylic monomers and vinyl comonomers, comprising at least one initiator selected from the group consisting of 1,1-diphenyl-3-methylpentyllithium, 1,1-diphenyl-hexyllithium and alpha-methylstyryllithium;

• and at least one alkali metal alcoholate of the formula R.sub.1 OLi, in which R.sub.1 is a straight- or branched-chain alkyl radical containing from 1 to 6 carbon atoms, an aryl radical or an arylalkyl radical.

Diblock copolymer comprising a structure A-B in which A is a block of a methacrylic monomer, a secondary or tertiary alkyl acrylate or a vinylaromatic monomer, and B denotes a primary alkyl acrylate block,

• wherein the number-average molecular weight of the block A is between 2,000 and 300,000, the number-average molecular weight of the block B is between 2,000 and 200,000, and the polydispersity index of the diblock copolymer is between 1.2 and 2.2.

An initiating system for the anionic polymerization of (meth)acrylic monomers or the anionic copolymerization of (meth)acrylic monomers and vinyl comonomers, comprising at least one initiator of the formula R-M (I) in which M is an alkali metal or an alkaline-earth metal;

• and R is an aryl radical or an alkylaryl radical;
• and at least one alcoholate of the formula R.sub.1 OM.sub.1 in which R.sub.1 is a straight- or branched-chain alkyl radical containing from 1 to 6 carbon atoms, an aryl radical or an arylalkyl radical;
• and M.sub.1 is sodium, potassium, rubidium or caesium.

A process for the preparation of a diblock copolymer of the structure A-B in which A is a block of a methacrylic monomer, a secondary or tertiary alkyl acrylate or a vinylaromatic monomer, and B denotes a primary alkyl acrylate block, wherein the number-average molecular weight of the block A is between 2,000 and 300,000, the number-average molecular weight of the block B is between 2,000 and 200,000, and the polydispersity index of the diblock copolymer is between 1.2 and 2.2, wherein in a first stage, the anionic polymerization of monomer A is conducted with the aid of an initiating system comprising at least one initiator of the formula R-M (I) in which M is an alkali metal or an alkaline-earth metal;

• and R is a straight- or branched-chain alkyl radical containing 2 to 6 carbon atoms, an aryl radical, or an arylalkyl radical, and at least one alcoholate of the formula R.sub.1 OM.sub.1 in which R.sub.1 is a straight- or branched-chain alkyl radical containing from 1 to 6 carbon atoms, an aryl radical or an arylalkyl radical;
• and M.sub.1 is sodium, potassium, rubidium or caesium, excluding the initiating systems alkyl lithium and R.sub.1 OM.sub.1, when R.sub.1 is an alkyl, to prepare a living chain unit of monomer A, and in a second stage the living chain unit of monomer A is reacted with monomer B in the presence of the initiating system of the first stage.

The process according to claim 29 wherein the initiator is present during polymerization in a molar ratio relative to the sum of said monomers A and B which does not exceed approximately 10.sup.-2.