A compound having formula (I)
wherein R
1
is methyl or ethyl; R
2
is hydrogen, methyl, CH
2
C(NH
2
)(R
1
)(CH
2
OH) or R
2
groups combine to form a difunctional C
2
-C
6
alkyl group; and X is a difunctional group selected from the group consisting of C
2
-C
20
alkyl, C
5
-C
20
cycloalkyl, C
6
-C
10
aryl, C
8
-C
20
aryl alkyl, C
4
-C
20
heteroalkyl or C
10
-C
20
aryl heteroalkyl.
A compound having formula (I)
wherein R1 is methyl or ethyl; R2 is hydrogen, methyl, CH2C(NH2)(R1)(CH2OH) or R2 groups combine to form a difunctional C2-C6 alkyl group; and X is a difunctional group selected from the group consisting of C2-C20 alkyl, C5-C20 cycloalkyl, C6-C10 aryl, C8-C20 aryl alkyl, C4-C20 heteroalkyl or C10-C20 aryl heteroalkyl.