Novel pH-responsive granules with tunable volumes from oxidized corn starches.

•Novel pH-responsive oxidized starch granules were successfully developed.•Preparation was carried out by TEMPO-mediated oxidation and pregelatinization.•The granules possessed intact granule morphology with envelopes.•Oxidized starch molecules control pH-responsivity to tune the granule volumes.•The granules considerably shrink and swell at pH 2 and 7, respectively.