Biodegradable polyesters for water-resistant anhydrous suncare formulations

A method of making an anhydrous sunscreen formulation, said method comprising the steps of:

• providing (a) at least one sunscreen active agent;
• providing (b) at least one waterproofing polymer;
• and
• combining (a) and (b) to form the anhydrous sunscreen formulation,
• wherein the at least one waterproofing polymer is a substantially non-sequential reaction product of the following components:
• (i) at least one polyglycerol;
• (ii) at least one dimer acid;
• and (iii) at least one fatty acid having 8-30 carbon atoms;
• wherein (iii) and (i) are in a molar ratio of less than 2:1;
• and
• wherein the at least one polyglycerol comprises a mixture of oligoglycerols having the following oligomer distribution:
• (a) 0 to 30 wt % glycerol;
• (b) 10 to 40 wt % diglycerol;
• (c) 10 to 65 wt % triglycerol;
• (d) 2 to 25 wt % tetraglycerol;
• (e) 0 to 15 wt % pentaglycerol;
• (f) 0 to 15 wt % hexaglycerol;
• (g) 0 to 10 wt % heptaglycerol;
• (h) 0 to 10 wt % octaglycerol;
• (i) 0 to 5 wt % nonaglycerol;
• and
• (j) 0 to 5 wt % decaglycerol;
• and
• wherein all weight percentages are based on 100 wt % of the at least one polyglycerol.

An anhydrous formulation comprising a waterproofing polymer that is a reaction product of:

• (i) a polyglycerol comprising a combination of diglycerol, triglycerol, tetraglycerol, pentaglycerol, hexaglycerol, heptaglycerol, and octaglycerol;
• and optionally one or more of glycerol, nonaglycerol, decaglycerol, undecaglycerol, dodecaglycerol, and combinations thereof;
• (ii) a C36 hydrogenated dimer acid;
• and
• (iii) isostearic acid;
• wherein (i), (ii) and (iii) are reacted in a molar ratio of about [1:(0.5 to 0.67):
• (0.67 to 1)].