Thermo- and UV-responsive amphiphilic nanogels via reversible [4+4] photocycloaddition of PEG/PCL-based polyurethane dispersions

Autor(es)

Fonseca, Lucas Polo ^[1] ; Felisberti, Maria Isabel ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Chem, POB 6154, BR-13084971 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: EUROPEAN POLYMER JOURNAL; v. 160, NOV 5 2021.
• Citações Web of Science: 0

Resumo

Amphiphilic nanogels are emerging as promising materials for several applications due to their high loading capacity of hydrophobic substances. In this context, a thermoresponsive anthracene end-capped hyperbranched polyurethane (HPU-AM) based on poly(ethylene glycol), polycaprolactone-triol, and isophorone diisocyanate, was used as a platform for nanogel preparation. Both polymer synthesis and functionalization with anthracene were one-pot and controlled. HPU-AM self-assembled in aqueous solutions to form micelles, while heating above the solution cloud point (T-cp) led to phase separation and globule formation, as verified by H-1 nuclear magnetic resonance and dynamic light scattering experiments. Nanogel dispersions were prepared by UV-irradiation of the globule dispersions. The UV-light (lambda = 365 nm) triggers the {[}4+4] cycloaddition of the anthracene chain-ends, yielding chemically cross-linked nanogels. Their hydrodynamic radius was tuned from 28 to 50 nm by varying the quench temperature (T > T-cp) and HPU-AM concentration. Evidence of nanogel softness, spherical morphology, narrow size distributions, and phase-segregated inner structure was provided by microscopy, light scattering, and Nile-red loading experiments. The hydrodynamic volume of the nanogels was reversibly reduced up to 85% by heating from 15 to 45 degrees C. Finally, irradiation of the nanogel dispersions at lambda = 280 nm cleaved the anthracene dimer, partially reverting the crosslinking, and promoting nanogel disaggregation into micelles of hydrodynamic radius of 7 nm. (AU)

• Processo FAPESP: 15/25406-5 - Organizando a matéria: colóides formados por associação de surfactantes, polímeros e nanopartículas
• Beneficiário: Watson Loh
• Modalidade de apoio: Auxílio à Pesquisa - Temático