Melamine-formaldehyde aerogels

Claim 2

A composition of matter comprising a low density, melamine=formaldehyde (MF) aerogel which s transparent and essentially colorless, wherein the cell/pore sizes of the aerogel are less than or equal to 500 angstroms (A) and the density of the aerogel is from about 0.1 to 0.8 g/cc.

Claim 3

The composition of claim 1, wherein the aerogel has a surface area of about 1000 m 2 /g.

Claim 4

The composition of claim 1, wherein the aerogel has a light blue haze.

Claim 5

A composition according to claim 1 wherein the density is from about 0.1 to about 0.75 g/cc.

Claim 6

A composition according to claim 1 wherein the aerogel is composed of interconnected particles or fibers with diameters less than 500 angstroms (A).

Claim 7

A melamine-formaldehyde aerogel having cell/pore sizes of less than or equal to 500 angstroms (A) and a density of from about 0.1 to about 0.8 g/cc produced by a method comprising the steps of: a) mixing formaldehyde and melamine in a predetermined ratio wherein there is an excess of formaldehyde in water in the pressure of a base catalyst; b) heating the mixture to a predetermined temperature for a sufficiently long period of time to form a clear solution; c) allowing the solution to cool to a predetermined temperature and then adding a sufficient amount of an acid to make the solution acidic; d) allowing the acidic melamine-formaldehyde solution to cure for a sufficient time at a predetermined temperature to e) placing the gel in a basic solution to neutralize the acid within the pores of the gel; f) replacing the aqueous solution within the pores of the gel with a suitable organic solvent; and g) critical point drying the gel.

Claim 8

A melamine-formaldehyde aerogel having cell/pore sizes of less than or equal to 500 angstroms (A) and a density of from about 0.1 to about 0.8 g/cc produced by a method comprising the steps of: a) mixing formaldehyde and melamine in a predetermined ratio wherein there is an excess of formaldehyde in water in the pressure of a base catalyst; b) heating the mixture to a predetermined temperature for a sufficiently long period of time to form a clear solution; c) allowing the solution to cool to a predetermined temperature and then adding a sufficient amount of an acid to make the solution acidic; d) allowing the acidic melamine-formaldehyde solution to cure for a sufficient time at a predetermined temperature to e) placing the gel in a basic solution to neutralize the acid within the pores of the gel; f) replacing the aqueous solution within the pores of the gel with a suitable organic solvent; and g) critical point drying the gel.

Claim 9

A melamine-formaldehyde aerogel according to claim 6: a) wherein the formaldehyde and melamine are mixed in a ratio from about 3:1 to about 6:1 moles in the presence of from about 10 to about 100 millimoles of sodium hydroxide; b) wherein the mixture is heated in step (b) to a temperature of from about 65° C. to about 75° C. for a period of from about five to about twenty minutes; c) wherein the solution in step (c) is cooled to from about 40° C. to about 50° C. and concentrated hydrochloric acid is added to change the pH to from about 1 to about 2 when measured at about 23° C.; d) wherein before step (d), if desired, because of solids in the solution, the cooled acidic solution from step (c) is reheated in a sealed container to a temperature of from about 40° C. to about 95° C.; e) wherein the basic solution of step (e) is ammonium hydroxide; f) wherein the organic solvent of step (f) is acetone; and g) wherein in step (g) carbon dioxide is a supercritical fluid.

Claim 10

A melamine-formaldehyde aerogel according to claim 7 wherein instead of steps (a)-(c), a melamine-formaldehyde polymer is mixed with water and a sufficient amount f an acid to effect a pH of from about 1 to about 2.5 and wherein step (e) is omitted.