A composition comprising: - a polyformal-isocyanate prepolymer comprising the reaction products of reactants comprising a polyformal polyol and a first diisocyanate; - a polythioether-isocyanate prepolymer comprising the reaction products of reactants comprising a polythioether polyol and a second diisocyanate and - a curing agent comprising an amine, wherein the polyformal polyol comprises a polyformal polyol selected from a polyformal polyol of Formula , a polyformal polyol of Formula , and a combination thereof: wherein: each w is independently selected from an integer from 1 to 50; z is an integer from 3 to 6; each R 3 is independently C 2-6 alkanediyl; each R 4 is independently selected from hydrogen, C 1-6 alkyl, C 7-12 phenylalkyl, substituted C 7-12 phenylalkyl, C 6-12 cycloalkylalkyl, substituted C 6-12 cycloalkylalkyl, C 3-12 cycloalkyl, substituted C 3-12 cycloalkyl, C 6-12 aryl, and substituted C 6-12 aryl; and E represents the core of an z-valent parent polyol E(OH) z and wherein the polythioether polyol comprises a polythioether polyol of Formula ; -R 1 -[-S-(CH 2 ) 2 -O-[-R 2 -O-] m -(CH 2 ) 2 -S-R 1 -] n - wherein: each R 1 is independently selected from C 2-6 alkanediyl. C 6-8 cycloalkanediyl, C 6-10 alkanecycloalkanediyl. -[(-CH 2 -) p -X-] q -(-CH 2 -) r -, and -[(CH 2 -) p -X-] q -(-CH 2 -) r -, wherein at least one -CH 2 - group is substituted with a methyl group; each R 2 is independently selected from C 2-6 alkanediyl, C 6-8 cycloalkanediyl, C 6-10 alkanecycloalkanediyl, and -[(-CH 2 -) p -X-] q -(-CH 2 -) r -; each X is selected from -O-. -S- and -NR 10 -,_wherein R 10 is selected from hydrogen and methyl; each m is independently selected from a rational number from 0 to 10; each n is independently selected from an integer from 1 to 60; each p is independently selected from an integer from 2 to 6; each q is independently selected from an integer from 0 to 5; and each r is independently selected from an integer from 2 to 10. - a polyformal-isocyanate prepolymer comprising the reaction products of reactants comprising a polyformal polyol and a first diisocyanate; - a polythioether-isocyanate prepolymer comprising the reaction products of reactants comprising a polythioether polyol and a second diisocyanate and - a curing agent comprising an amine, each w is independently selected from an integer from 1 to 50; z is an integer from 3 to 6; each R 3 is independently C 2-6 alkanediyl; each R 4 is independently selected from hydrogen, C 1-6 alkyl, C 7-12 phenylalkyl, substituted C 7-12 phenylalkyl, C 6-12 cycloalkylalkyl, substituted C 6-12 cycloalkylalkyl, C 3-12 cycloalkyl, substituted C 3-12 cycloalkyl, C 6-12 aryl, and substituted C 6-12 aryl; and E represents the core of an z-valent parent polyol E(OH) z and each R 1 is independently selected from C 2-6 alkanediyl. C 6-8 cycloalkanediyl, C 6-10 alkanecycloalkanediyl. -[(-CH 2 -) p -X-] q -(-CH 2 -) r -, and -[(CH 2 -) p -X-] q -(-CH 2 -) r -, wherein at least one -CH 2 - group is substituted with a methyl group; each R 2 is independently selected from C 2-6 alkanediyl, C 6-8 cycloalkanediyl, C 6-10 alkanecycloalkanediyl, and -[(-CH 2 -) p -X-] q -(-CH 2 -) r -; each X is selected from -O-. -S- and -NR 10 -,_wherein R 10 is selected from hydrogen and methyl; each m is independently selected from a rational number from 0 to 10; each n is independently selected from an integer from 1 to 60; each p is independently selected from an integer from 2 to 6; each q is independently selected from an integer from 0 to 5; and each r is independently selected from an integer from 2 to 10. <EOS>