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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Author(s):
Fonseca, Lucas Polo [1] ; Felisberti, Maria Isabel [1]
Total Authors: 2
Affiliation:
[1] Univ Estadual Campinas, Inst Chem, POB 6154, BR-13084971 Campinas, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: EUROPEAN POLYMER JOURNAL; v. 160, NOV 5 2021.
Web of Science Citations: 0
Abstract

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)

FAPESP's process: 15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles
Grantee:Watson Loh
Support Opportunities: Research Projects - Thematic Grants