A composition for forming a sealant, the composition comprising: a silane-terminated polythioether component represented by Formula 2: (Y a A b)SiR 4 Z'-[-S-R 1 -S-(CH 2) p -O-(-R 2 -O-) m -(CH 2) q] n -S-R 1 -S-Z'R 4 Si(Y a A b) wherein: R 1 is selected from the group consisting of C 2 to C 10 n-alkylene groups, C 2 to C 6 branched alkylene groups, C 6 to C 8 cycloalkylene groups, C 6 to C 10 alkylcyloalkylene groups, heterocyclic groups, -[(-CH 2) p -X] q -(CH 2) r - groups, and -[(-CH 2) p -X] q -(-CH 2) r - groups in which at least one -CH 2 - unit is substituted with a methyl group; R 2 is selected from the group consisting of C 2 to C 10 n-alkylene groups, C 2 to C 6 branched alkylene groups, C 6 to C 8 cycloalkylene groups, C 6 to C 14 alkylcyloalkylene groups, heterocyclic groups, and -[(-CH 2) p -X] q -(CH 2) r -groups; Y is a hydrolyzable and condensable functional group; A is selected from the group consisting of C1 to C4 hydrocarbon functional groups; X is selected from the group consisting of O atoms, S atoms, and-NR 3 - groups, wherein R 3 is selected from the group consisting of H atoms and methyl groups; Z' is a functional group resulting from a reaction between mercaptan and a functional group selected from the group consisting of isocyanate groups, epoxy groups and vinyl groups; R 4 is a C1 to C3 hydrocarbon chain; m is an integer ranging from 1 to 50; n is an integer ranging from 1 to 60; p is an integer ranging from 2 to 6; q is an integer ranging from 1 to 5; r is an integer ranging from 2 to 10; and a and b are each an integer ranging from 0 to 3, and the sum of a and b is 3; a catalyst; and a filler. a silane-terminated polythioether component represented by Formula 2: (Y a A b)SiR 4 Z'-[-S-R 1 -S-(CH 2) p -O-(-R 2 -O-) m -(CH 2) q] n -S-R 1 -S-Z'R 4 Si(Y a A b) wherein: R 1 is selected from the group consisting of C 2 to C 10 n-alkylene groups, C 2 to C 6 branched alkylene groups, C 6 to C 8 cycloalkylene groups, C 6 to C 10 alkylcyloalkylene groups, heterocyclic groups, -[(-CH 2) p -X] q -(CH 2) r - groups, and -[(-CH 2) p -X] q -(-CH 2) r - groups in which at least one -CH 2 - unit is substituted with a methyl group; R 2 is selected from the group consisting of C 2 to C 10 n-alkylene groups, C 2 to C 6 branched alkylene groups, C 6 to C 8 cycloalkylene groups, C 6 to C 14 alkylcyloalkylene groups, heterocyclic groups, and -[(-CH 2) p -X] q -(CH 2) r -groups; Y is a hydrolyzable and condensable functional group; A is selected from the group consisting of C1 to C4 hydrocarbon functional groups; X is selected from the group consisting of O atoms, S atoms, and-NR 3 - groups, wherein R 3 is selected from the group consisting of H atoms and methyl groups; Z' is a functional group resulting from a reaction between mercaptan and a functional group selected from the group consisting of isocyanate groups, epoxy groups and vinyl groups; R 4 is a C1 to C3 hydrocarbon chain; m is an integer ranging from 1 to 50; n is an integer ranging from 1 to 60; p is an integer ranging from 2 to 6; q is an integer ranging from 1 to 5; r is an integer ranging from 2 to 10; and a and b are each an integer ranging from 0 to 3, and the sum of a and b is 3; R 1 is selected from the group consisting of C 2 to C 10 n-alkylene groups, C 2 to C 6 branched alkylene groups, C 6 to C 8 cycloalkylene groups, C 6 to C 10 alkylcyloalkylene groups, heterocyclic groups, -[(-CH 2) p -X] q -(CH 2) r - groups, and -[(-CH 2) p -X] q -(-CH 2) r - groups in which at least one -CH 2 - unit is substituted with a methyl group; R 2 is selected from the group consisting of C 2 to C 10 n-alkylene groups, C 2 to C 6 branched alkylene groups, C 6 to C 8 cycloalkylene groups, C 6 to C 14 alkylcyloalkylene groups, heterocyclic groups, and -[(-CH 2) p -X] q -(CH 2) r -groups; Y is a hydrolyzable and condensable functional group; A is selected from the group consisting of C1 to C4 hydrocarbon functional groups; X is selected from the group consisting of O atoms, S atoms, and-NR 3 - groups, wherein R 3 is selected from the group consisting of H atoms and methyl groups; Z' is a functional group resulting from a reaction between mercaptan and a functional group selected from the group consisting of isocyanate groups, epoxy groups and vinyl groups; R 4 is a C1 to C3 hydrocarbon chain; m is an integer ranging from 1 to 50; n is an integer ranging from 1 to 60; p is an integer ranging from 2 to 6; q is an integer ranging from 1 to 5; r is an integer ranging from 2 to 10; and a and b are each an integer ranging from 0 to 3, and the sum of a and b is 3; a catalyst; and a filler.