Polymer compounds

1. A composition comprising a pre-formed, hydrolytically susceptible non-addition polyanionic polymer comprising polymer strands formed from at least one ethylenically unsaturated monomer, wherein the polymer strands are linked by at least one linking moiety comprising a hydrolytically susceptible bond formed with a multidentate compound comprising two or more ethylenically unsaturated moieties, each such moiety being linked to the multidentate compound through a hydrolytically susceptible bond, wherein at least one of which monomers has:

i) one or more functional groups that can be titrated with base to form negatively charged functional groups, or

ii). one or more precursor groups that are precursors of the functional groups that can be titrated with base; which precursor groups are converted to the functional groups;

wherein at least one of the ethylenically unsaturated monomers is according to the formula:

(R 3 )(R 2 )C═C(R 1 )—X—Y

wherein:

Y is —C(O)OR 4 ; —O—S(O 2 )OR 4 ; —S(O 2 )OR 4 ; or —S(O)OR 4 ; wherein R 4 is hydrogen or a cleavage permitting group;

X is a direct bond; a straight or branched alkylene group having one to six carbon atoms, one or more of which can be replaced by O, S, or N heteroatoms, provided that there is no heteroatom in a position α or β to Y; phenylene; a five or six membered heteroarylene having up to three heteroatoms independently selected from O, S, and N, provided that neither Y or (R 3 )(R 2 )C═C(R 1 )— is bonded to a heteroatom; and

R 1 , R 2 and R 3 are independently selected from, hydrogen, C 1 -C 6 alkyl, carboxy, halogen, cyano, isocyanato, C 1 -C 6 hydroxyalkyl, alkoxyalkyl having 2 to 12 carbon atoms, C 1 -C 6 haloalkyl, C 1 -C 6 cyanoalkyl, C 3 -C 6 cycloalcyl, C 1 -C 6 carboxyalkyl, aryl, hydroxyaryl, haloaryl, cyanoaryl, C 1 -C 6 alkoxyaryl, carboxyaryl, nitroaryl, or a group —X—Y; wherein C 1 -C 6 alkyl or C 1 -C 6 alkoxy groups are either linear or branched and up to Q-2 carbon atoms of any C 3 -C 6 cycloalkyl group, wherein Q is the total number of ring carbon atoms in the cycloalkyl group, are independently replaced with O, S, or N heteroatoms; with the proviso that neither doubly-bonded carbon atom is directly bonded to O or S; and wherein aryl is phenyl or a 5 or 6 membered heteroaryl having up to three heteroatoms selected from the group consisting of O, S, and N.

2. The composition of claim 1 , wherein the linking moiety is formed by copolymerization of an ethylenically unsaturated linking agent, and the mole fraction of ethylenic double bonds in the combination from which the polyanionic polymer is made that is contributed by the ethylenically unsaturated linking agent is 0.02 or less.

3. The composition of claim 1 , comprising a microgel formed of the polyanionic polymer.

4. The composition of claim 3 , wherein the microgel has a ratio of the macroviscosity of the microgel to the microviscosity of the microgel is 10,000 or less.

5. The composition of claim 1 , wherein the polyanionic polymer is functionalized to provide one or more pendant functional groups selected from hydroxy, acyl halide, chloroformate, and mercapto; and wherein

the linking moiety provides crosslinking and is a reaction product of the pendant groups between polymer segments or between the pendant groups and complementing functions groups of a linking group.

6. The composition of claim 5 , wherein the linking agent is the diacrylate of an α,ω-diol or the diacrylate of a chain extended α,ω-diol.