resumo
The development of easy, translucent, and scalable UV-protection coatings for transparent containers is of utmost importance to ensure the safety of several food and medical products. Here it is studied the preparation of coatings based on carbon quantum dots (C-QDs) with very high absolute emission quantum yields (above 55%) for an excitation wavelenght of 360 nm, and polyvinyl alcohol, using the same temperature but employing two different heating-assisted (conventional and microwave oven-assisted heating) hydrothermal syntheses. The microwave oven-assisted heating allows the formation of the C-QDs in only 1 min, while 180 min are needed to produce them in a conventional oven. The impact of dip-coating withdrawal rates on the coatings properties, such as thickness, UV protective ability and colour is extensively studied. The coatings made under microwave oven-assisted heating achieved superior UV absorbance and colour gain. The best coatings were either the ones prepared under conventional oven for 300 min or the ones synthetised by microwave oven over 15 min, displaying 85% or 92% of UV protection capacity, respectively. The selection of the best conditions strongly depends on the level of colour deemed acceptable, with the microwave oven coatings showing more intense colour gain.
palavras-chave
LIGHT; GLASS; RADIATION; BLOCKING; LIQUID; PVA
categoria
Chemistry; Materials Science; Physics
autores
Silva, MRF; Alves, MFRP; Ananias, D; Ivanov, M; Fernandes, MHV; Vilarinho, PM; Ferreira, P
nossos autores
Duarte Ananias
Investigador Auxiliar
Manuel Fellipe Rodrigues Pais Alves
Estudante de doutoramento
Maria Helena Figueira Vaz Fernandes
Professor(a) Jubilado(a)
Mariana Rodrigues Ferreira da Silva
Estudante de doutoramento
Maxim Ivanov
Investigador
Paula Celeste da Silva Ferreira
Investigador Coordenador
Paula Maria Lousada Silveirinha Vilarinho
Vice-DiretorGrupos
G1 - Materiais Porosos e Nanossistemas
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G5 - Materiais Biomiméticos, Biológicos e Vivos
Projectos
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This research was funded by CLEVER project NO. POCI 01-0247-FEDER-039699 co-financed by European Regional Development Fund (ERDF) to Portugal. This work was also developed within the scope of the project CICECO - Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) financed by national funds by the Fundacao para a Ciencia e a Tecnologia (FCT)/Ministerio da Educacao e Cultura (MEC) through the program PIDDAC (Programa de Investimento e Despesa de Desenvolvimento da Administracao Central). MRFS and MFRPA are thankful to FCT for the PhD-grant SFRH/BD/145661/2019 and PhD-grant (2021.06615. BD), respectively. The authors thank Antonio Fernandes for his technical assistance on Raman measurements.