Thermosetting compositions containing hydroxy functional polymers prepared by atom transfer radical polymerization

A thermosetting composition comprising a co-reactable solid, particulate mixture of:

• (a) a capped polyisocyanate crosslinking agent;
• and
• (b) hydroxy functional nonrandom copolymer prepared by atom transfer radical polymerization, in the presence of an initiator having at least one radically transferable group, and in which said polymer contains at least one of the following polymer chain structures:
• Φ-[[—(M)p—(G)q]x—(M)r—T]z
• and
• Φ-[[—(G)q—(M)p]x—(G)s—T]z
• wherein M is a residue, that is free of hydroxyl functionality, of at least one ethylenically unsaturated radically polymerizable monomer;
• G is a residue, that has hydroxyl functionality, of at least one ethylenically unsaturated radically polymerizable monomer;
• Φ is a residue from the initiator, free from the radically transferable group, selected from the group consisting of sulfonyl compounds, diethyl 2-halo-2-methylmalonates and mixtures thereof;
• T is or is derived from the radically transferable group and is selected from the group consisting of halides and a dehalogenation reaction product of a limited radically polymerizable ethylenically unsaturated compound;
• p and q represent average numbers of residues occurring in a block of residues in each polymer chain structure;
• x represents the number of radically transferable groups;
• x is independently from 1 to 100 for each structure;
• p and q are each independently within the range of 1 to 100 for each x-segment and for each structure;
• r and s are each independently for each structure within the range of 1 to 100;
• z is independently for each structure at least 1;
• and said hydroxyl functional polymer has a number average molecular weight of at least 250 to 16,000 and a polydispersity index of less than 2.0.