A biodegradable cationic block copolymer, comprising: first repeat units derived from a first cyclic carbonyl monomer by a ring opening polymerization, the first cyclic monomer having a structure of formula: wherein: t is an integer from 0 to 6 and when t is 0 carbons labeled 4 and 6 are linked together by a single bond; each Y is -O-; and each Q 1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, carboxy groups, alkyl groups comprising 1 to 30 carbons, aryl groups comprising 6 to 30 carbon atoms, and groups having the structure wherein M 1 is a monovalent radical selected from the group consisting of -R 1, -OR 1, - NHR 1, -NR 1 R 1, and -SR 1; and each R 1 is a monovalent radical independently selected from the group consisting of alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbons; and wherein one or more of the Q 1 groups of the first cyclic carbonyl monomer comprises a monovalent leaving group capable of reacting with a tertiary amine to form a quaternary amine by ring-opening polymerization, and wherein more than 0% of the first repeat units comprise a side chain moiety comprising a quaternary amine group; a second repeat unit derived from a second cyclic carbonyl monomer of formula, and the second repeat unit comprises a side chain acetal ester group, and wherein the second cyclic carbonyl monomer is not capable of reacting with the tertiary amine to form any quaternary amine; a subunit derived from a monomeric diol initiator for the ring-opening polymerization; and an optional endcap group. first repeat units derived from a first cyclic carbonyl monomer by a ring opening polymerization, the first cyclic monomer having a structure of formula: wherein: t is an integer from 0 to 6 and when t is 0 carbons labeled 4 and 6 are linked together by a single bond; each Y is -O-; and each Q 1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, carboxy groups, alkyl groups comprising 1 to 30 carbons, aryl groups comprising 6 to 30 carbon atoms, and groups having the structure wherein M 1 is a monovalent radical selected from the group consisting of -R 1, -OR 1, - NHR 1, -NR 1 R 1, and -SR 1; and each R 1 is a monovalent radical independently selected from the group consisting of alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbons; and wherein one or more of the Q 1 groups of the first cyclic carbonyl monomer comprises a monovalent leaving group capable of reacting with a tertiary amine to form a quaternary amine by ring-opening polymerization, and wherein more than 0% of the first repeat units comprise a side chain moiety comprising a quaternary amine group; t is an integer from 0 to 6 and when t is 0 carbons labeled 4 and 6 are linked together by a single bond; each Y is -O-; and each Q 1 is a monovalent radical independently selected from the group consisting of hydrogen, halides, carboxy groups, alkyl groups comprising 1 to 30 carbons, aryl groups comprising 6 to 30 carbon atoms, and groups having the structure wherein M 1 is a monovalent radical selected from the group consisting of -R 1, -OR 1, - NHR 1, -NR 1 R 1, and -SR 1; and each R 1 is a monovalent radical independently selected from the group consisting of alkyl groups comprising 1 to 30 carbons, and aryl groups comprising 6 to 30 carbons; and wherein one or more of the Q 1 groups of the first cyclic carbonyl monomer comprises a monovalent leaving group capable of reacting with a tertiary amine to form a quaternary amine by ring-opening polymerization, and wherein more than 0% of the first repeat units comprise a side chain moiety comprising a quaternary amine group; a second repeat unit derived from a second cyclic carbonyl monomer of formula, and the second repeat unit comprises a side chain acetal ester group, and wherein the second cyclic carbonyl monomer is not capable of reacting with the tertiary amine to form any quaternary amine; a subunit derived from a monomeric diol initiator for the ring-opening polymerization; and an optional endcap group.