A film comprising a regioselectively substituted cellulose ester comprising: (i) a plurality of R 1 -CO- substituents; (ii) a plurality of R 4 -CO- substituents; (iii) a plurality of hydroxyl substituents, wherein the degree of substitution of R 1 -CO- at the C2 position ("C2DS R1 ") is in the range of from about 0.2 to about 1.0, wherein the degree of substitution of R 1 -CO- at the C3 position ("C3DS R1 ") is in the range of from about 0.2 to about 1.0, wherein the degree of substitution of R 4 -CO- at the C6 position ("C6DS R4 ") is in the range of from about 0.1 to about 1.0, wherein the degree of substitution of hydroxyl is in the range of from about 0 to about 2.6, wherein R 1 is chosen from (C 1-20)alkyl; halo(C 1-20)alkyl; (C 2-20)alkenyl, (C 3-7)cycloalkyl, (C 6-20)aryl, wherein the aryl is unsubstituted or substituted by 1 to 6 R 2 groups; or a 5- to 20 membered heteroaryl containing 1 to 3 heteroatoms independently selected from oxygen, sulfur, and nitrogen, wherein the heteroaryl is unsubstituted or substituted by 1 to 6 R 3 groups, wherein R 2 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro, wherein R 3 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro; wherein R 4 is chosen from (C 1-20)alkyl; halo(C 1-5)alkyl; (C 2-20)alkenyl, (C 3-7)cycloalkyl, (C 6-20)aryl, wherein the aryl is unsubstituted or substituted by 1 to 6 R 5 groups; or monocyclic or bicyclic heteroaryl containing 1 to 3 heteroatoms independently selected from oxygen, sulfur, and nitrogen, wherein the heteroaryl is unsubstituted or substituted by 1 to 6 R 6 groups, R 5 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro, and R 6 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro; characterized in that the degree of substitution of R 1 -CO- at the C6 position ("C6DS R1 ") is less than 0.1; and wherein the regioselectively substituted cellulose ester comprises a plurality of alkyl-acyl substituents and a plurality of aryl-acyl substituents. (i) a plurality of R 1 -CO- substituents; (ii) a plurality of R 4 -CO- substituents; (iii) a plurality of hydroxyl substituents, wherein the degree of substitution of R 1 -CO- at the C2 position ("C2DS R1 ") is in the range of from about 0.2 to about 1.0, wherein the degree of substitution of R 1 -CO- at the C3 position ("C3DS R1 ") is in the range of from about 0.2 to about 1.0, wherein the degree of substitution of R 4 -CO- at the C6 position ("C6DS R4 ") is in the range of from about 0.1 to about 1.0, wherein the degree of substitution of hydroxyl is in the range of from about 0 to about 2.6, wherein R 1 is chosen from (C 1-20)alkyl; halo(C 1-20)alkyl; (C 2-20)alkenyl, (C 3-7)cycloalkyl, (C 6-20)aryl, wherein the aryl is unsubstituted or substituted by 1 to 6 R 2 groups; or a 5- to 20 membered heteroaryl containing 1 to 3 heteroatoms independently selected from oxygen, sulfur, and nitrogen, wherein the heteroaryl is unsubstituted or substituted by 1 to 6 R 3 groups, wherein R 2 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro, wherein R 3 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro; wherein R 4 is chosen from (C 1-20)alkyl; halo(C 1-5)alkyl; (C 2-20)alkenyl, (C 3-7)cycloalkyl, (C 6-20)aryl, wherein the aryl is unsubstituted or substituted by 1 to 6 R 5 groups; or monocyclic or bicyclic heteroaryl containing 1 to 3 heteroatoms independently selected from oxygen, sulfur, and nitrogen, wherein the heteroaryl is unsubstituted or substituted by 1 to 6 R 6 groups, R 5 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro, and R 6 is chosen from (C 1-6)alkyl, halo(C 1-6)alkyl, (C 1-6)alkoxy, halo(C 1-6)alkoxy, halo, (C 3-7)cycloalkyl, (C 6-10)aryl, or nitro; characterized in that the degree of substitution of R 1 -CO- at the C6 position ("C6DS R1 ") is less than 0.1; and wherein the regioselectively substituted cellulose ester comprises a plurality of alkyl-acyl substituents and a plurality of aryl-acyl substituents.