Antimicrobial siloxane quaternary ammonium salts

A siloxane quaternary ammonium salt having either the general formula A, ##STR19## wherein:

• (1) each of R.sub.1 -R.sub.7 is independently selected from the group consisting of monovalent C.sub.1 -C.sub.20 alkyl, phenyl, and phenyl-substituted C.sub.1 -C.sub.20 alkyl groups, in which each phenyl can be substituted or unsubstituted;
• (2) each of R.sub.8 and R.sub.9 is a monovalent group independently selected from the group consisting of (a) hydrogen and (b) monovalent alkyl, cycloalkyl, aryl, and heterocyclic groups and combinations thereof having up to about 30 carbon atoms, except that both R.sub.8 and R.sub.9 cannot be hydrogen;
• or, when taken together in combination with the carbon atom to which they are attached, R.sub.8 and R.sub.9 represent a carbonyl group;
• (3) each of R.sub.10 and R.sub.11 is a methyl group;
• (4) a represents an integer from 1 to about 20;
• (5) b represents an integer from 1 to about 20;
• (6) Z is a monovalent group having from about 8 to about 30 carbon atoms and selected from the group consisting of alkyl, cycloalkyl, aryl, and heterocyclic groups, and combinations thereof, wherein Z is terminated by an alkyl moiety which includes at least about 8 carbon atoms in a single continuous chain;
• (7) Y.sub.1 is an anion which does not cause thermal degradation of the siloxane quaternary ammonium salt to be more than 36 weight % when heated to 232.degree. C. for 30 minutes under a nitrogen atmosphere;
• and
• (8) said siloxane quaternary ammonium salt has a molecular weight of from about 600 to about 1,700;
• or the general formula B, ##STR20## wherein:
• (1) each of R.sub.20 -R.sub.23 is independently selected from the group consisting of monovalent C.sub.1 -C.sub.20 alkyl, phenyl, and phenyl-substituted C.sub.1 -C.sub.20 alkyl groups, in which each phenyl can be substituted or unsubstituted;
• (2) n represents an integer of from 1 to about 19;
• (3) each of Q.sub.1 and Q.sub.2 represents an independently selected quaternary ammonium group having the general formula, ##STR21## in which:
• (a) R.sub.24 is a monovalent alkyl group having from about 8 to about 30 carbon atoms, at least about 8 carbon atoms of which make up a single continuous chain;
• (b) R.sub.25 and R.sub.26 methyl groups;
• (c) each of R.sub.27 and R.sub.28 is a monovalent group selected from the group consisting of (i) hydrogen and (ii) monovalent alkyl, cycloalkyl, aryl, and heterocyclic groups and combinations thereof having up to about 30 carbon atoms, except that both R.sub.27 and R.sub.28 cannot be hydrogen;
• or, when taken together in combination with the carbon atom to which they are attached, R.sub.27 and R.sub.28 represent a carbonyl group;
• (d) c represents an integer of from 2 to about 20;
• and
• (e) d represents an integer of from 2 to about 20;
• (4) Y.sub.2 is an anion which does not cause thermal degradation of the siloxane quaternary ammonium salt to be more than 36 weight % when heated to 232.degree. C. for 30 minutes under a nitrogen atmosphere;
• and
• (5) said siloxane quaternary ammonium salt has a polydispersity of up to about 3.0 and a weight-average molecular weight of from about 800 to about 2,000.