Foams and methods of forming foams of chain extended/branched copolymers of vinylidene substituted aromatic monomers

1 . A foaming composition comprising:

(a) one or more copolymers having nucleophilic groups, prepared from one or more vinylidene aromatic monomers and one or more unsaturated compounds containing the nucleophilic groups, the one or more copolymers having nucleophilic groups have on average 0.02 to less than 0.25 percent by weight of nucleophilic groups pendant from the one or more copolymers having nucleophilic groups;

(b) one or more copolymers having electrophilic groups, prepared from one or more vinylidene aromatic monomers and one or more unsaturated compounds having electrophilic groups, wherein the one or more copolymers having electrophilic groups are present in an amount of 0.1 to about 0.5 percent by weight of the foaming composition; and

(c) one or more blowing agents,

wherein the nucleophilic groups of the one or more copolymers having nucleophilic groups and the electrophilic groups of the one or more copolymers having electrophilic groups react and form branched and/or chain extended and un-crosslinked copolymers during a process of forming a foam from the foaming composition; and wherein the branched and/or chain extended and un-crosslinked copolymers are soluble in methylene chloride at 23° C. and exhibit a polydispersity of 2.5 or greater.

2 . The foaming composition according to claim 1 wherein the nucleophilic groups are one or more of carboxylic acid, alcohol, phenol, amine, aniline, imidazole, tetrazole, thiol, boronic acid, glycol, hydrazine and hydroxyl amine groups and the electrophilic groups are one or more of epoxide, anhydride, imide, ester, acyl halide, acyl nitrile, aldehyde, ketone, isocyanate and isothiocyanate groups.

3 . The foaming composition according to claim 1 wherein the nucleophilic groups are carboxylic acid groups and the electrophilic groups are epoxide groups.

4 . The foaming composition according to claim 1 , wherein the one or more copolymers having the electrophilic groups contain about 10 to about 60 percent by weight of the electrophilic groups.

5 . The foaming composition according to claim 1 , wherein the branched and/or chain extended and un-crosslinked copolymers have a M z from about 300 kg/mole to about 1,000 kg/mole and a M w from about 100 kg/mole to about 400 kg/mole and a viscosity ratio, low shear viscosity at 0.314 s −1 /higher shear viscosity at 628 s −1 , of about 25 or greater.

6 . The foaming composition of claim 1 , wherein the foaming composition comprises a zinc salt selected from the group consisting of zinc acetate, zinc acetate dihydrate and zinc carbonate.

7 . The foaming composition of claim 6 , wherein the zinc salt is present in an amount of about 10 ppm to about 5000 ppm by weight or less based on the weight of the foaming composition.

8 . The foaming composition of claim 1 which comprises a zinc salt in which zinc forms a salt with an acetate, carbonate, bicarbonate, methacrylate, fumarate or mixtures thereof.

9 . A method of forming a foam comprising:

a) heating a foaming composition comprising one or more copolymers having nucleophilic groups prepared from of one or more vinylidene aromatic monomers and one or more unsaturated compounds containing the nucleophilic groups, the one or more copolymers having nucleophilic groups have on average about 0.02 to less than 0.25 percent by weight of nucleophilic groups pendant from the one or more copolymers having nucleophilic groups; one or more copolymers having electrophilic groups prepared from one or more vinylidene aromatic monomers and one or more unsaturated compounds having the electrophilic groups, wherein the one or more copolymers having electrophilic groups are present in an amount of 0.1 to about 0.5 percent by weight of the foaming composition; and one or more blowing agents, to a temperature sufficient to melt and react the one or more copolymers having nucleophilic groups and the one or more copolymers having electrophilic groups to form a branched and/or chain extended and un-crosslinked copolymers; and

b) extruding the foaming composition from a higher pressure to a lower pressure to form an extruded foam comprised of the branched and/or chain extended and un-crosslinked copolymers; and wherein the branched and/or chain extended and un-crosslinked copolymers are soluble in methylene chloride at 23° C. and exhibit a polydispersity of 2.5 or greater.

10 . The method according to claim 9 wherein the nucleophilic groups are one or more of carboxylic acid, alcohol, phenol, amine, aniline, imidazole, tetrazole, thiol, boronic acid, glycol, hydrazine and hydroxyl amine groups and the electrophilic groups are one or more of epoxide, anhydride, imide, ester, acyl halide, acyl nitrile, aldehyde, ketone, isocyanate and isothiocyanate groups.

11 . The method of claim 9 wherein the composition contains a salt comprising a salt of a metalloid or a metal salt, the metal salt being a transition metal, an alkali metal, an alkaline earth metal, or a post transition metal.

12 . The method of claim 11 wherein the metal salt is a zinc salt in which zinc forms a salt with an acetate, carbonate, bicarbonate, methacrylate, fumarate or mixtures thereof.

13 . The method of claim 12 , wherein the zinc salt is zinc acetate, zinc acetate dihydrate or zinc carbonate.

14 . The method of claim 13 wherein the zinc salt is present in an amount of about 10 ppm to about 5000 ppm by weight or less based on the weight of the foaming composition.

15 . The method of claim 9 , wherein the one or more copolymers having the electrophilic groups contain about 10 to about 60 percent by weight of the electrophilic groups.

16 . The method according to claim 9 wherein the nucleophilic groups are carboxylic acid groups and the electrophilic groups are epoxide groups.

17 . A foam comprised of a branched and/or chain extended and un-crosslinked copolymer that is a reaction product of a foaming composition comprising (i) one or more copolymers having nucleophilic groups prepared from one or more vinylidene aromatic monomers and one or more unsaturated compounds containing the nucleophilic groups, the one or more copolymers have on average about 0.02 to less than 0.25 percent by weight of nucleophilic groups pendant from the one or more copolymers having nucleophilic groups and (ii) one or more copolymers having electrophilic groups prepared from one or more vinylidene aromatic monomers and one or more unsaturated compounds having the electrophilic groups, wherein the one or more copolymers having electrophilic groups are present in an amount of 0.1 to about 0.5 percent by weight based on the weight of the foaming composition; and wherein the branched and/or chain extended and un-crosslinked copolymer is soluble in methylene chloride at 23° C. and exhibits a polydispersity of 2.5 or greater.

18 . The foam of claim 17 , wherein the foam comprises a zinc salt in which zinc forms a salt with an acetate, carbonate, bicarbonate, methacrylate, fumarate or mixtures thereof.

19 . The foam of claim 18 , wherein the zinc salt is zinc acetate, zinc acetate dihydrate or zinc carbonate.

20 . The foam of claim 17 , wherein the branched and/or chain extended and un-crosslinked copolymer has a M z from about 300 kg/mole to about 1,000 kg/mole and a M w from about 100 kg/mole to about 400 kg/mole and a viscosity ratio, low shear viscosity at 0.314 s −1 /higher shear viscosity at 628 s −1 , of about 25 or greater.