gels Review Functional Stimuli-Responsive Gels: Hydrogels and Microgels Coro Echeverria 1,* ID , Susete N. Fernandes 2 ID , Maria H. Godinho 2, João Paulo Borges 2 ID and Paula I. P. Soares 2,* 1 Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Calle Juan de la Cierva 3, Madrid 28006, Spain 2 I3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, Caparica 2829-516, Portugal;
[email protected] (S.N.F.);
[email protected] (M.H.G.);
[email protected] (J.P.B.) * Correspondence:
[email protected] (C.E.);
[email protected] (P.I.P.S.); Tel.: +351-212948564 (P.I.P.S.) Received: 4 May 2018; Accepted: 8 June 2018; Published: 12 June 2018 Abstract: One strategy that has gained much attention in the last decades is the understanding and further mimicking of structures and behaviours found in nature, as inspiration to develop materials with additional functionalities. This review presents recent advances in stimuli-responsive gels with emphasis on functional hydrogels and microgels. The first part of the review highlights the high impact of stimuli-responsive hydrogels in materials science. From macro to micro scale, the review also collects the most recent studies on the preparation of hybrid polymeric microgels composed of a nanoparticle (able to respond to external stimuli), encapsulated or grown into a stimuli-responsive matrix (microgel). This combination gave rise to interesting multi-responsive functional microgels and paved a new path for the preparation of multi-stimuli “smart” systems.