Ladder copolymer

A process for preparing a polymer, the process comprising polymerizing a monomer mixture comprising

• a) a polyether-modified polysiloxane having at least two polyether segments and at least two polymerizable ethylenically unsaturated groups attached to at least two of the at least two polyether segments, and one polysiloxane segment, said polysiloxane segment having a number average molecular weight in the range of 400 to 6000 g/mol, and said polysiloxane segment being positioned between the at least two polyether segments, and
• b) at least one other further monomer having one polymerizable ethylenically unsaturated group,
• the polymer comprising
• a) at least two polymer backbone chains and
• b) at least one polymeric connecting chain comprising at least two polyether segments and one polysiloxane segment, said polysiloxane segment having a number average molecular weight in the range of 400 to 6000 g/mol, and at least one of the at least two polyether segments being positioned between the at least two polymer backbone chains and the polysiloxane segment,
• wherein the at least two polymer backbone chains are linked by the at least one polymeric connection chain, and wherein the polymer has a weight average molecular weight in the range of 2000 to 200000 g/mol, determined via GPC using polystyrene standards and tetrahydrofuran as eluent, and
• wherein the at least two polymer backbone chains are (co)polymers of polymerizable ethylenically unsaturated monomers.

A process of forming a multilayer coating system on a substrate comprising the steps of

• i) applying a coating composition a) to a substrate to form a coating layer a) and
• ii) applying a coating composition b) to form a coating layer b) on top of coating layer a),
• wherein at least one of coating composition a) or coating composition b) comprises a polymer in an amount of 0.01 to 15.00% by weight, based on the total non-volatile content of the coating composition,
• wherein the polymer comprises
• a) at least two polymer backbone chains and
• b) at least one polymeric connecting chain comprising at least two polyether segments and one polysiloxane segment, said polysiloxane segment having a number average molecular weight in the range of 400 to 6000 g/mol, and at least one of the at least two polyether segments being positioned between the at least two polymer backbone chains and the polysiloxane segment,
• wherein the at least two polymer backbone chains are linked by the at least one polymeric connection chain, and wherein the polymer has a weight average molecular weight in the range of 2000 to 200000 g/mol, determined via GPC using polystyrene standards and tetrahydrofuran as eluent.