Method for producing hydrophobically modified acrylic rheology modifers

A method for preparing hydrophobically modified rheology modifiers;

• said method comprising polymerizing a monomer mixture comprising:
• (i) a monomer selected from the group consisting of:
• (a) H2C═C(R)C(O)X(CH2CH2O)n(CH(R′)CH2O)mR″;
• (b) H2C═C(R)C6H4C(CH3)2NHCO2(CH2CH2O)n(CH(R′)CH2O)mR″;
• and combinations thereof;
• wherein X is O or NH, R is H or CH3, R′ is C1-C2 alkyl;
• R″ is C8-C22 alkyl, C8-C16 alkylphenyl or C13-C36 aralkylphenyl;
• n is an average number from 6-100 and m is an average number from 0-50, provided that n≧m and m+n is 6-100;
• and
• (ii) a C3-C6 carboxylic acid monomer;
• wherein at least 30% of polymerization occurs in the presence of an oxidant, a reductant and a metal catalyst, and substantially in the absence of a peroxide, hydroperoxide or perester containing an alkyl group having at least five carbon atoms.