Bioerodible poly(ortho esters) containing amine groups, and block copolymers containing them

A poly (ortho ester) of formula I or formula II: (See formula) wherein R * is a C1 - 4; R is a bond, (CH2) a-, or - (CH2) bonds (CH2) c-; wherein a is an integer of 1 to 10 and b and c are integers independently numbers from 1 to 5; n is an integer of at least 5; and each A is independently selected from R 1, R 2, R 3 and R 4, wherein R 1 is: (See formula) wherein: p is an integer from 1 to 20; R 5 is hydrogen or C1 - 4; and R 6 is: (See formula) where: s is an integer from 0 to 30; t is an integer from 2 to 200; and R 7 is hydrogen or C1 - 4; R 2 is: (Omitted) R 3 is: (See formula) wherein: x is an integer from 0 to 30; and is an integer of 2 to 200; R 8 is hydrogen or C1 - 4; R 9 and R 10 are independently alkylene C1 - 12; R 11 is hydrogen or C1 - 6 and R12 is C1 - 6; or R 11 and R 12 together are C3 - 10; and R 4 is the residue of a diol containing at least one amine functionality incorporated therein; in which at least 0.1 mol% of the A units are R1 and at least 0.1 mol% of the A units are R 4.