PEG-POE, PEG-POE-PEG, and POE-PEG-POE block copolymers

A block copolymer of formula X, formula Y, or formula Z:

• R1—[OCH2CH2]f—[POE]g—H (X),R1—[OCH2CH2]f—[POE]g—[OCH2CH2]h—OR2 (Y),H—A—[POE]g—[OCH2CH2]h—[POE]j—H (Z),
• where:
• R1 is C1-4 alkyl;
• R2 is C1-4 alkyl;
• f and h are independently an integer from 2 to 1000;
• g and j are independently an integer from 2 to 200;
• POE is a poly(ortho ester) of formula I or formula II:
• 16
• where:
• R3 is a bond, —(CH2)a—, or —(CH2)b—O—(CH2)c—;
• where a is an integer of 1 to 10, and b and c are independently integers of 1 to 5;
• R4 is a C1-4 alkyl;
• and
• each A is R5, R6, or R7, where
• R5 is:
• 17
• where:
• p is an integer of 1 to 20;
• R8 is hydrogen or C1-4 alkyl;
• and
• R9 is:
• 18
• where:
• s is an integer of 0 to 30;
• t is an integer of 2 to 20;
• and
• R10 is hydrogen or C1-4 alkyl;
• R6 is:
• 19
• R7 is a diol containing at least one functional group independently selected from amide, imide, urea, and urethane groups;
• where A is R7 in at least 0.1 mol % of the POE units when the poly(ortho ester) is of formula I.