| 摘要 |
A composition comprising a cyclic oligomer of the formula <IMAGE> Ia. <IMAGE> Ib. wherein X is selected from the group consisting of alkylene of two to twelve carbon atoms, inclusive, alkylidene of one to twelve carbon atoms, inclusive, cycloalkylene of four to twelve carbon atoms, inclusive cycloalkylidene of four to twelve carbon atoms, inclusive, -S-, -O-, -S-S-, <IMAGE> a is zero or 1; n and m are the same or different and are integers of one to about fifteen; R is alkylene of two to eight carbon atoms, inclusive or alkylidene of one to eight carbon atoms, inclusive, phenylene or a single bond. R1 and R2 are the same or different and are alkyl of one to four carbon atoms, inclusive or halo; b and c are the same or different and are integers of zero to four; and R3 and R4 are the same or different and are alkyl of one to eight carbon atoms, inclusive, phenyl, hydrogen or R3 and R4 are taken together to form an alkylene of two to eight carbon atoms inclusive.
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