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Overview of Membrane Science and Technology in Portugal
Publication . Tomé, Liliana C.; Santos, Diogo M. F.; Velizarov, Svetlozar; Coelhoso, Isabel M.; Mendes, Adélio; Crespo, João G.; de Pinho, Maria Norberta; LAQV@REQUIMTE; DQ - Departamento de Química; MDPI AG
Membrane research in Portugal is aligned with global concerns and expectations for sustainable social development, thus progressively focusing on the use of natural resources and renewable energy. This review begins by addressing the pioneer work on membrane science and technology in Portugal by the research groups of Instituto Superior Técnico—Universidade de Lisboa (IST), NOVA School of Science and Technology—Universidade Nova de Lisboa (FCT NOVA) and Faculdade de Engenharia—Universidade do Porto (FEUP) aiming to provide an historical perspective on the topic. Then, an overview of the trends and challenges in membrane processes and materials, mostly in the last five years, involving Portuguese researchers, is presented as a contribution to a more sustainable water–energy–material–food nexus.
Stimuli-Responsive Cellulose Nanocrystals based Materials
Publication . Almeida, Ana Rita Gonçalves Lobato de; Fernandes, Susete; Baptista, Ana
The continued demand for the sustainable products has emerged due to the environmental awareness, prompting the development of the new polymeric materials whose properties change when subjected to the external stimuli; these are called the “intelligent” polymers or the stimuli-responsive polymers. The cellulose nanocrystals (CNCs) have a high versatility of the physical, chemical and biological properties, making them excellent candidates for the production of the sustainable products that respond to stimuli. Thus, the main objective of this project involved the production and the characterisation of a stimuli-responsive composite material based on the CNCs functionalised with a chromophore and coated with a conductive polymer, polypyrrole (PPy).
The CNCs suspensions were produced from the cellulose microcrystals derived from the cotton, by the process of the acid hydrolysis. A new product has emerged, Azo-CNCs, from its functionalisation with azobenzene (Azo) derivative. The materials were characterised by the techniques of ATR-FTIR, EA, CP/MAS 13C NMR, UV-Vis spectroscopy, AFM and TGA/DSC, and the wettability was determined. The CNCs with an average nanoparticle length of 166 ± 55 nm gave rise to Azo-CNCs with 219 ± 62 nm. This new product presents reversible photoisomerisation, when suspended in THF, with full isomerization after 5 minutes of UV irradiation. It showed a hydrophobic behaviour (water contact angle 96.3) in film form, but after irradiation with UV light, it became hydrophilic (water contact angle of 65). It was still sensitive to low pH with a photochromic response.
The CNCs were also coated with polypyrrole using the in situ chemical polymerization of pyrrole. The influence of poly(N-vinylpyrrolidone) (PVP) as a surface modifier was additionally studied and, since the CNCs became less hydrophilic, the deposition of PPy onto their surface was promoted, increasing its conductivity.
The composite systems containing Azo-CNCs and PPy-CNCs will lead to the use of the CNCs in advanced and promising applications, complementing their versatility and renewability
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
3599-PPCDT
Número da atribuição
PTDC/CTM-BIO/6178/2014