{'fraction_non_alphanumeric': 0.035398230088495575, 'fraction_numerical': 0.004424778761061947, 'mean_word_length': 6.067708333333333, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Light-driven sequential shape transformation of block copolymer particles through three-dimensional confined self-assembly.

Shape-controlled block copolymer (BCP) particles that respond to light stimulus have drawn great attention due to their promising applications in smart materials, yet polymeric particles with light-triggered controllable sequential shape transformation (SST) are still rarely reported. By confined co-assembly of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) and azo-containing light-responsive additives within emulsions, herein, we fabricated BCP particles with light-controlled SST behavior. Attributed to the quaternization of P2VP chains with bromoalkyl additives and the trans-cis isomerization of an azo group under UV light, the interfacial interactions between the BCPs and the surrounding aqueous phase are significantly varied; therefore, the particles exhibit three distinct phases in sequence: (1) elongation of ellipsoidal particles with increasing domain spacing; (2) shape transformation of elongated ellipsoidal particles into accordion-like particles; and (3) disassembly of polymer particles into small spheres. In addition, these particles with SST behavior can be used in light-controlled drug release at a high spatial-temporal resolution, demonstrating their potential in clinical settings and biomedicine.