Use of amphiphilic surface modifying additives to improve performance of siloxane-polyurethane fouling-release coatings

1. A method for reducing or preventing biofouling of a surface exposed to an aqueous environment comprising the steps of:

coating the surface with a curable coating composition to form a coated surface, and

curing the coating composition on the coated surface,

wherein the curable coating composition comprises:

a) at least one surface modifying amphiphilic additive consisting of the reaction product of

a1) at least one Si—H functional siloxane; and

a2) at least one allyl-functional poly(ethylene glycol) monomethyl ether; and

b) at least one siloxane-polyurethane coating composition comprising the reaction product of

b1) at least one aminopropyl terminated polydimethyl siloxane;

b2) at least one polyol; and

b3) at least one polyisocyanate crosslinker; and

c) optionally, at least one additive;

wherein the curable coating composition comprises 0.1-10 wt. % of the at least one surface modifying amphiphilic additive, based on the total weight of the curable coating composition,

wherein the Si—H functional siloxane is a tetra functional Si—H cyclosiloxane.

2. The method of claim 1 , wherein the tetra functional Si—H cyclosiloxane is selected from Si—H functional 1,3,5,7-tetramethylcyclotetrasiloxane (D′4).

3. The method of claim 1 , wherein the allyl functional poly(ethylene glycol) monomethyl ether is selected from at least one allyl-terminated poly(ethylene glycol) monomethyl ether.

4. The method of claim 1 , wherein the Si—H functional siloxane and the allyl functional poly(ethylene glycol) monomethyl ether are present in a molar ratio of 1.0: 1.0.

5. The method of claim 1 , wherein the polyol is an acrylic polyol, a polyester polyol, a polycarbonate polyol, a polyether polyol, or mixtures thereof.

6. The method of claim 1 , wherein the polyol is a polyether polyol.

7. The method of claim 1 , wherein the polyisocyanate crosslinker is selected from the group consisting of isophorone diisocyanate, hexamethylene diisocyanate, methylene diphenyl diisocyanate, and derivatives thereof.

8. The method of claim 1 , wherein the polyisocyanate crosslinker is isophorone diisocyanate or a derivative thereof and the polyol is an acrylic polyol.

9. The method of claim 1 , wherein the polyisocyanate crosslinker is methylene diphenyl diisocyanate or a derivative thereof and the polyol is a polyether polyol.

10. The method of claim 1 , wherein the curable coating composition comprises 5-10 wt. % of the at least one surface modifying amphiphilic additive, based on the total weight of the curable coating composition.

11. The method of claim 1 , wherein the surface modifying amphiphilic additive consists of poly(ethylene glycol) chains attached to the backbone of the Si—H functional siloxane.

12. The method of claim 1 , wherein the curable coating composition comprises 1-10 wt. % of the at least one surface modifying amphiphilic additive, based on the total weight of the curable coating composition.

13. The method of claim 3 , wherein the at least one allyl-terminated poly(ethylene glycol) monomethyl ether has a molecular weight ranging from about 200 g/mol to about 1,500 g/mol.

14. The method of claim 1 , wherein the surface is present on the hull of a marine vessel.

15. The method of claim 1 , wherein the surface is present on a structure submerged in seawater.

16. The method of claim 1 , wherein the additive is selected from the group consisting of pigments, curing catalysts, pot-life extenders, solvents, and mixtures thereof.

17. The method of claim 1 , wherein the curable coating composition comprises 0.1-5 wt. % of the at least one surface modifying amphiphilic additive, based on the total weight of the curable coating composition.

18. The method of claim 1 , wherein:

the tetra functional Si—H cyclosiloxane is selected from Si—H functional 1,3,5,7-tetramethylcyclotetrasiloxane (D′4);

the allyl functional poly(ethylene glycol) monomethyl ether is selected from at least one allyl-terminated poly(ethylene glycol) monomethyl ether;

the Si—H functional siloxane and the allyl functional poly(ethylene glycol) monomethyl ether are present in a molar ratio of 1.0: 1.0;

the polyol is an acrylic polyol, a polyester polyol, a polycarbonate polyol, a polyether polyol, or mixtures thereof; and

the polyisocyanate crosslinker is selected from the group consisting of isophorone diisocyanate, hexamethylene diisocyanate, methylene diphenyl diisocyanate, and derivatives thereof.

19. The method of claim 18 , wherein the at least one allyl-terminated poly(ethylene glycol) monomethyl ether has a molecular weight ranging from about 200 g/mol to about 1,500 g/mol.

20. The method of claim 18 , wherein the polyisocyanate crosslinker is isophorone diisocyanate or a derivative thereof and the polyol is an acrylic polyol.

21. The method of claim 18 , wherein the polyisocyanate crosslinker is methylene diphenyl diisocyanate or a derivative thereof and the polyol is a polyether polyol.

22. A curable coating composition comprising:

a) at least one surface modifying amphiphilic additive consisting of the reaction product of

a1) at least one Si—H functional siloxane; and

a2) at least one allyl-functional poly(ethylene glycol) monomethyl ether; and

b) at least one siloxane-polyurethane coating composition comprising the reaction product of

b1) at least one aminopropyl terminated polydimethyl siloxane;

b2) at least one polyol; and

b3) at least one polyisocyanate crosslinker; and

c) optionally, at least one additive;

wherein the curable coating composition comprises 0.1-10 wt. % of the at least one surface modifying amphiphilic additive, based on the total weight of the curable coating composition,

wherein the Si—H functional siloxane is a tetra functional Si—H cyclosiloxane.