title: Photo-response behavior of electrospun nanofibers based on spiropyran-cyclodextrin modified polymer.
abstract: Tunable and durable photochromic materials are a rapidly expanding area of interest, with applications ranging from biomedical devices to industrial-fields. Here we examine electrospun poly (methacrylic acid) PMAA nanofibers covalently modified with the highly photochromic molecule, spiropyran (SP) or a derivate SP which is firstly coupled to a cyclodextrin molecule (βCDSP). The photochromic properties of the starting materials and of the nanofibers were investigated. βCDSP, PMAASPand PMAA-βCDSPpolymers exhibited a reverse photochromism. The kinetic results revealed a faster isomerization process for the βCDSPmolecule, than that for the PMAA-βCDSPand for the PMAASP, the slowest one. The fastest isomerization is attributed to the presence of a large number of hydroxyl groups of the βCD which stabilizes the merocyanine formviahydrogen bonding, and the slowest isomerization is related to the PMAA chain structure that stabilizes the spiropyran form. Thus, combining the PMAA and βCD properties the photo-isomerization can be modulated. The photoreversibility of this material was verified by UV-visible measurements cycling visible and UV light. Infrared spectroscopy and water contact angle were used for the nanofiber surface characterization, demonstrating the presence of the spiropyran on the mats surface and also showing a minimal effect on nanofiber size and shape when compared to PMAA fiber.
authors.affiliation: Laboratório de Encapsulamento Molecular e Biomateriais (LEMB) - Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, 31270-901, MG, Brazil; Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
authors.forename: Frederico B
authors.initials: FB
authors.lastname: De Sousa
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA; Institute for Biotechnology and Bioengineering, Center for Biological and Chemical Engineering, Instituto Superior Técnico, Lisboa, Portugal.
authors.forename: João D T
authors.initials: JD
authors.lastname: Guerreiro
authors.affiliation: David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA; Department of Anesthesiology, Children Hospital Boston, 300 Longwood Avenue, Boston, MA, 02115, USA.
authors.forename: Minglin
authors.initials: M
authors.lastname: Ma
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Anderson
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
authors.forename: Chester L
authors.initials: CL
authors.lastname: Drum
authors.affiliation: Laboratório de Encapsulamento Molecular e Biomateriais (LEMB) - Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, 31270-901, MG, Brazil.
authors.forename: Rubén D
authors.initials: RD
authors.lastname: Sinisterra
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Langer