Metathesis depolymerizable surfactants
A class of surfactant molecules whose structure includes regularly spaced unsaturation in the tail group and thus, can be readily decomposed by ring-closing metathesis, and particularly by the action of a transition metal catalyst, to form small molecule products. These small molecules are designed to have increased volatility and/or enhanced solubility as compared to the original surfactant molecule and are thus easily removed by solvent extraction or vacuum extraction at low temperature. By producing easily removable decomposition products, the surfactant molecules become particularly desirable as template structures for preparing meso- and microstructural materials with tailored properties.
1. A surfactant of formula (1),
wherein
A is a hydrophilic head group or a polar head group, wherein the polar head group is alkoxide, alkyl sulfide, phenolate, thiophenolate, carboxylate, sulfate, sulfonate including sulfated polyethylenated alcohol, sulfated triglyceride, sulfosuccinate, phosphate, phosphonate, polyphosphonate, carbonate, borate, —NR′R″R′″ + , —P R′R″R′″ + , —SR′R″ + , guanidnium, pyridinium, or other quaternized heterocyclic amines, wherein R′, R″, R′″ each represent hydrogen or any aliphatic, cyclic or aromatic organic group, with or without further substitution, polyoxyethylenated alkyl phenol, tertiary acetylenic glycol, pyrrolidone, alkylglycoside, or a zwitterion;
B is a linker, comprising at least one alkyl or aryl group; and
C is an unsaturated hydrocarbon tail, wherein C is represented by (2),
wherein R 1 , R 2 , R 3 , and R 4 are the same or different and are hydrogen, straight or branched chain alkyl groups that can contain heteroatom functionalities, or cyclic alkyl chains; n is at least 2; a is 1 to 6; m is equal or greater than 1; and p is at least 1.
2. The surfactant of claim 1 , wherein R 1 and R 2 are straight or branched chain alkyl groups.
3. The surfactant of claim 2 wherein either or both R 1 and R 2 contain a heteroatom.
4. The surfactant of claim 2 , wherein the alkyl groups contain at least one singly substituted aromatic group and wherein the singly substituted aromatic group contains one heteroatom.
5. The surfactant of claim 1 , wherein B is unsubstituted (CH 2 ) r or a branched (CRR′) n linear or cyclic alkyl chain, wherein n>O.
6. The surfactant of claim 1 , wherein B is an unsubstituted or substituted aromatic ring.
7. The surfactant of claim 6 , wherein A and C are ortho, meta- orpara- about B.
8. The surfactant of claim 1 , wherein B is substituted by at least one fluorine substituent.
9. The surfactant of claim 1 , wherein B comprises a chain of two or more unsubstituted or multiply substituted aromatic rings, wherein substitution is alkyl or heteroatom-containing alkyl or combinations thereof.
10. The surfactant of claim 1 , wherein the tail group C is a metathesis-active organic moiety.
11. The surfactant of claim 10 , wherein the tail group is oligo-(1,5-pentadienyl), oligo-(1,6-hexadienyl) or oligo-(1,7-heptadienyl) that can be unsubstituted or substituted, wherein the substitutions are straight chain alkyl or branched alkyl groups, straight chain alkyl or branched alkyl groups containing heteroatoms, unsubstituted or multiply substituted aromatic groups, unsubstituted or multiply substituted aromatic groups containing heteroatoms.
12. The surfactant of claim 10 , wherein the tail group is fluorinated.
13. A surfactant comprising two spaced apart surfactants according to claim 1 , wherein the two surfactants are covalently bonded through a tethering group, wherein the tethering group bonds either both head groups, both linker groups, or both tail groups of said surfactant together and wherein said spaced apart surfactants are the same or different.
14. The surfactant of claim 13 , wherein the tethering group contains a metathesis degradable moiety.
15. The surfactant of claim 13 , wherein the tethering group is oligiodienyl or alkenyl.
16. The surfactant of claim 13 , wherein the tethering group is fluorinated.
17. The surfactant of claim 13 , wherein the head group of at least one of the component surfactant molecules is a polar head group.
18. The surfactant of claim 13 , wherein at least one linker group is an aromatic group.
19. The surfactant of claim 18 , wherein the aromatic group is substituted and wherein the substitution is alkyl or heteroatom-containing alkyl.
20. The surfactant of claim 18 , wherein the head groups and the tail groups are arranged ortho, meta- orpara- about the linker groups.
21. The surfactant of claim 13 , wherein at least one linker group comprises a chain of two or more aromatic groups.
22. The surfactant of claim 21 , wherein at least one of the aromatic groups contains at least one substitution, wherein the substitution is alkyl or heteroatom-containing alkyl.
23. The surfactant dipotassium heneicosa-2,8,14,20-tetraenyl malonate.
24. The surfactant 13-(triphenylphosphonium)trideca-1,7-dienyl iodide.
25. The surfactant 19-(triphenylphosphonium)nonadeca-1,7-dienyl iodide.
26. The surfactant 19-(N,N,N-trimethylammonium)nonadeca-1,7,13-trienyl iodide.