Regioselectively substituted cellulose esters and films made therefrom

A regioselectively substituted cellulose ester comprising:

• (a) a plurality of chromophore-acyl substituents;
• and
• (b) a plurality of pivaloyl substituents,
• (c) a plurality of (C1-6)alkyl-acyl substituents,
• wherein the cellulose ester has a hydroxyl degree of substitution (“DSOH”) in the range of from 0 to 0.9,
• wherein the cellulose ester has a pivaloyl degree of substitution (“DSPv”) in the range of from 0.1 to 1.2,
• wherein the cellulose ester has a chromophore-acyl degree of substitution (“DSCh”) in the range of from 0.4 to 1.6, and
• wherein the regioselectivity is such that the sum of the chromophore-acyl degree of substitution at C2 and C3 (“C2DSCh” and “C3DSCh”) minus the chromophore-acyl degree of substitution at C6 (“C6DSCh”) is between 0.1 and 1.6,
• wherein the chromophore-acyl is chosen from a heteroaryl-acyl, wherein the heteroaryl is a 5- to 10-membered ring having 1- to 4- heteroatoms chosen from N, O, or S, and wherein the heteroaryl is unsubstituted or substituted by 1-5 R1;
• wherein each R1 is independently chosen from nitro, cyano, (C1-6)alkyl;
• halo(C1-6)alkyl;
• (C6-20)aryl-CO2-;
• (C6-20)aryl;
• (C1-6)alkoxy;
• halo(C1-6)alkoxy;
• halo;
• 5- to 10-membered heteroaryl having 1-4 heteroatoms chosen from N, O, or S;
• or