Branched polymers and coating compositions made therefrom

A curable coating composition comprising a crosslinkable component and a crosslinking component wherein said crosslinkable component comprises:

• a branched acrylic polymer having a weight average molecular weight ranging from 2000 to 200,000, Tg ranging from −70° C. to +150° C., having on average 2 to 2000 crosslinkable groups, said acrylic polymer resulting from a free radical polymerization of a monomer mixture in the presence of a cobalt-containing chain transfer agent, said monomer mixture comprising at least two unsaturated monomers A and B of the formula:
• CH2═CXY
• wherein,
• a molar ratio of said monomer A to said monomer B in said monomer mixture ranges from 1.99:1 to 1:9;
• in the range of from 75% to 100% of said monomers A and B in said monomer mixture are converted into said polymer;
• X for monomer A is H and X for monomer B is CH3;
• Y is selected from the group consisting of OR, O2CR, halogen, CO2H, COR, CO2R, CN, CONH2, CONHR, CONR2 and R′;
• wherein
• R is selected from the group consisting of substituted and unsubstituted alkyl, substituted and unsubstituted aryl, substituted and unsubstituted heteroaryl, substituted and unsubstituted aralkyl, substituted and unsubstituted alkaryl, and substituted and unsubstituted organosilyl, the substituents being the same or different and selected from the crosslinkable group consisting of carboxyl, carboxylate, epoxy, silyl, hydroxyl, alkoxy, primary amino, secondary amino, tertiary amino, isocyanato, sulfonyl, halo, acetoacetyl, and combinations thereof,
• R′ is selected from the group consisting of substituted and unsubstituted aryl, and substituted and unsubstituted heteroaryl, the substituents being the same or different and selected from the crosslinkable group consisting of carboxyl, carboxylate, epoxy, silyl, hydroxyl, alkoxy, primary amino, secondary amino, tertiary amino, isocyanato, sulfonyl, substituted and unsubstituted alkyl, substituted and unsubstituted aryl, substituted and unsubstituted alkenyl, halo, and acetoacetyl;
• wherein hetero atom in said heteroaryl group is N, O, P or S, and the number of carbon atoms in:
• (i) said alkyl group range from 1 to 18, and
• (ii) said aryl group range from 6 to 18;
• and
• wherein said crosslinking component for said crosslinkable groups comprises a polyamine, a polyketimine, polyaldimine, polyepoxy, polyisocyanate, polyol, silane, melamine, polyaspartic ester, polyanhydride, polyacid or a combination thereof.