Thruster propellants

1 . A method of propelling a spacecraft comprising an electrospray thruster and a reservoir comprising a thruster propellant comprising a plurality of molecules, each of said molecules comprising a plurality of cations and a plurality of anions, each of said molecules having an overall net zero charge, each of said cations comprising two or more heads, and one or more tails with the proviso that when one or more of said tails are hydrophobic fluorinated tails, said hydrophobic fluorinated tails do not comprise sulfur, said one or more tails being covalently bound to said one or more heads, each of said one or more heads being independently selected from the group consisting of an imidazolium, an imidazolinium, a phosphonium, an ammonium, a sulfonium, a pyridinium, a pyrrolidinium, said method comprising electrospraying said thruster propellant from said electrospray thruster, wherein said thruster propellant comprises one or more organic linking groups that link one or more of said one or more heads, wherein for said thruster propellant each of said one or more linkers is independently selected from the group consisting of aliphatic, aromatic, poly(ether), (poly)thio(ether), and isocyanurate, wherein for said thruster propellant each of said cation's heads are independently selected from Formulas 3 through 14 below, wherein for each of Formulas 3 through 14:

a) each anion A is independently selected from the group consisting of chloride, bromide, iodide, tetrafluoroborate, hexafluorophosphate, and bis(trifluoromethylsulfonyl)azanide;

b) each R 1 is independently selected from the group consisting of: hydrogen; Formula 1 wherein the indice a is an integer from 1 to 20, and all the other limitations of Formula 1 are as specified; Formula 2 wherein the limitations of Formula 2 are as specified; a C 1 -C 12 branched alkane; a C 1 -C 12 linear alkane; a substituted aromatic moiety; or an unsubstituted aromatic moiety;

c) each R 2 , R 3 and R 4 is independently selected from the group consisting of hydrogen; Formula 1 wherein the limitations of Formula 1 are as; Formula 2 wherein the limitations of Formula 2 are as specified; a C 1 -C 12 branched alkane; a C 1 -C 12 linear alkane; a substituted aromatic moiety; or an unsubstituted aromatic moiety, with the proviso that for Formula 3, Formula 5 and Formula 6, adjacent R 3 and R 4 moieties can be one or more benzo moieties rather than single independent moieties;

d) indice e for each Formulas 10 through 14 is independently from 1 to 3;

e) each R 5 is independently selected from the group consisting of: hydrogen; Formula 1 wherein the indice a is an integer from 1 to 20, and all the other limitations of Formula 1 are as specified; a C 1 -C 12 branched alkane; a C 1 -C 12 linear alkane; a substituted aromatic moiety; and an unsubstituted aromatic moiety;

f) for each Formula 1 and Formula 2, each X is independently hydrogen or fluorine; for Formula 1 the indice a is an integer from 0 to 20; for Formula 2 the indice b is an integer from 0 to 10; for Formula 2 the indices c, d, and e, are each independently an integer from 0 to 10; and represents an attachment point for Formulas 1 and 2 below to at least one head of said molecule;

each of said head groups being covalently bound to another head group by a linking group that is covalently bound to at least one of R 1 , R 2 , R 3 , R 4 , or R 5 on each head group and each of said head groups being covalently bound to at least one tail by at least one of R 1 , R 2 , R 3 , R 4 , or R 5 on each head group that is not covalently bound to a linking group.

2 . The method of claim 1 wherein for said thruster propellant each of said one or more tails is independently an aliphatic moiety connected to a fluorinated carbon chain.

3 . The method of claim 1 wherein for said thruster propellant each of said one or more tails is independently selected from the group consisting of tails having Formula 1 or Formula 2 below wherein:

a) each X is independently hydrogen or fluorine;

b) for Formula 1 the indice a is an integer from 0 to 20;

c) for Formula 2 the indice b is an integer from 0 to 10;

d) for Formula 2 the indices c, d, and e, are each independently an integer from 0 to 10; and

e) represents an attachment point for Formulas 1 and 2 below to at least one head of said molecule;

4 . The method of claim 3 wherein for Formula 1 the indice a is an integer from 1 to 12, for Formula 2 the indice b is an integer from 1 to 5, and for Formula 2 the indices c, d, and e, are each independently an integer from 0 to 5.

5 . The method of claim 4 wherein for Formula 1 the indice a is an integer from 1 to 4, for Formula 2 the indice b is an integer from 1 to 3, and for Formula 2 the indice c is 0, the indice d is an integer from 1 to 4 and the indice e is an integer from 1 to 5.

6 . The s method of claim 5 wherein for Formula 1 the indice a is 3, for Formula 2 the indice b is 1, and for Formula 2 the indice c is 0, the indice d is 2 and the indice e is 4.

7 . The method of claim 1 wherein for said thruster propellant wherein each of said one or more linkers is aliphatic.

8 . The method of claim 7 wherein for said thruster propellant wherein each of said one or more aliphatic linkers is independently a C 1 -C 12 aliphatic.