title: Screen-Printed Photochromic Textiles through New Inks Based on SiO2@naphthopyran Nanoparticles.
abstract: Photochromic silica nanoparticles (SiO2@NPT), fabricated through the covalent immobilization of silylated naphthopyrans (NPTs) based on 2H-naphtho[1,2-b]pyran (S1, S2) and 3H-naphtho[2,1-b]pyran (S3, S4) or through the direct adsorption of the parent naphthopyrans (1, 3) onto silica nanoparticles (SiO2NPs), were successfully incorporated onto cotton fabrics by a screen-printing process. Two aqueous acrylic- (AC-) and polyurethane- (PU-) based inks were used as dispersing media. All textiles exhibited reversible photochromism under UV and solar irradiation, developing fast responses and intense coloration. The fabrics coated with SiO2@S1 and SiO2@S2 showed rapid color changes and high contrasts (ΔE*ab= 39-52), despite presenting slower bleaching kinetics (2-3 h to fade to the original color), whereas the textiles coated with SiO2@S3 and SiO2@S4 exhibited excellent engagement between coloration and decoloration rates (coloration and fading times of 1 and 2 min, respectively; ΔE*ab= 27-53). The PU-based fabrics showed excellent results during the washing fastness tests, whereas the AC-based textiles evidenced good results only when a protective transfer film was applied over the printed design.
authors.affiliation: REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal.
authors.forename: Tânia V
authors.initials: TV
authors.lastname: Pinto
authors.affiliation: REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Costa
authors.affiliation: Departamento de Química e CQ-VR, Universidade de Trás-os-Montes e Alto Douro , 5001-801 Vila Real, Portugal.
authors.forename: Céu M
authors.initials: CM
authors.lastname: Sousa
authors.affiliation: REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal.
authors.forename: Carlos A D
authors.initials: CAD
authors.lastname: Sousa
authors.affiliation: REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal.
authors.forename: Clara
authors.initials: C
authors.lastname: Pereira
authors.affiliation: Centro de Nanotecnologia e Materiais Técnicos, Funcionais e Inteligentes (CeNTI) , 4760-034 Vila Nova de Famalicão, Portugal.
authors.forename: Carla J S M
authors.initials: CJSM
authors.lastname: Silva
authors.affiliation: Laboratório de Catálise e Materiais (LCM), Laboratório Associado LSRE-LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto , 4200-465 Porto, Portugal.
authors.forename: Manuel Fernando R
authors.initials: MFR
authors.lastname: Pereira
authors.affiliation: Departamento de Química e CQ-VR, Universidade de Trás-os-Montes e Alto Douro , 5001-801 Vila Real, Portugal.
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Coelho
authors.affiliation: REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Freire
keywords: naphthopyrans; photochromism; screen-printing; silica nanoparticles; smart textiles