The bright and the dark side of the sphere: light-stabilized microparticles. Issue 3 (17th December 2020)

• Record Type: Journal Article
• Authors: Schmitt, Christian W.; Walden, Sarah L.; Delafresnaye, Laura; Houck, Hannes A.; Barner, Leonie; Barner-Kowollik, Christopher
• Is Part Of: Polymer chemistry. Volume 12:Issue 3(2021)
• Page Start: 449
• Page End: 457
• Publication Date: 2020-12-17
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/d0py01456g
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : We introduce degradable microparticles, synthesized from prepolymers in a precipitation-like polymerization. The narrow disperse particles are stabilized with continuous irradiation of green light and can be spontaneously degraded in the dark. Abstract : Visible light-triggered reversible triazolinedione (TAD) chemistry was already reported in the 1970s but it has only recently been introduced into the field of materials science, and as such remains relatively unexplored. Here, we exploit the reversible naphthalene-TAD Diels–Alder couple to crosslink pre-synthesized polymers in a precipitation-like polymerization to form narrow disperse microparticles. The approach does not require additives such as stabilizers or initiators and proceeds to deliver particles under relatively mild conditions in less than 1 h. While the crosslinked particles maintain their shape upon continuous irradiation with green light, the particles can be readily degraded in the dark at ambient temperature through a spontaneous cycloreversion process. In addition, the formation and degradation rate can be tuned by employing shorter or longer prepolymers, with particles synthesized from larger polymers degrading slower compared to their shorter polymer counterparts. The particle formation, light-stabilization and degradation were characterized in-depth by scanning electron microscopy (SEM) and online static light scattering experiments. In particular the particles' tuneable intrinsic degradation behaviour could hold key potential, for instance, in long term drug or fertilizer delivery systems.