Light-induced modulation of viscoelastic properties in azobenzene polymers
Photo-induced isomerization of azobenzene molecules drives mass migrations in azopolymer samples. The resulting macroscopic directional photo-deformation of the material morphology has found many applications in literature, although the fundamental mechanisms behind this mass transfer are still unde...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
De Gruyter
2024-01-01
|
| Series: | Nanophotonics |
| Subjects: | |
| Online Access: | https://doi.org/10.1515/nanoph-2023-0728 |
| _version_ | 1826963934833278976 |
|---|---|
| author | Chiodini Stefano Borbone Fabio Oscurato Stefano L. Garcia Pablo D. Ambrosio Antonio |
| author_facet | Chiodini Stefano Borbone Fabio Oscurato Stefano L. Garcia Pablo D. Ambrosio Antonio |
| author_sort | Chiodini Stefano |
| collection | DOAJ |
| description | Photo-induced isomerization of azobenzene molecules drives mass migrations in azopolymer samples. The resulting macroscopic directional photo-deformation of the material morphology has found many applications in literature, although the fundamental mechanisms behind this mass transfer are still under debate. Hence, it is of paramount importance to find quantitative observables that could drive the community toward a better understanding of this phenomenon. In this regard, azopolymer mechanical properties have been intensively studied, but the lack of a nanoscale technique capable of quantitative viscoelastic measurements has delayed the progress in the field. Here, we use bimodal atomic force microscopy (AFM) as a powerful technique for nanomechanical characterizations of azopolymers. With this multifrequency AFM approach, we map the azopolymer local elasticity and viscosity, with high resolution, after irradiation. We find that, while in the (previously) illuminated region, a general photo-softening is measured; locally, the Young modulus and the viscosity depend upon the inner structuring of the illuminating light spot. We then propose a possible interpretation based on a light-induced expansion plus a local alignment of the polymer chains (directional hole-burning effect), which explains the experimental observations. The possibility to access, in a reliable and quantitative way, both Young modulus and viscosity could trigger new theoretical–numerical investigations on the azopolymer mass migration dynamics since, as we show, both parameters can be considered measurable. Furthermore, our results provide a route for engineering the nanomechanical properties of azopolymers, which could find interesting applications in cell mechanobiology research. |
| first_indexed | 2024-03-08T05:29:30Z |
| format | Article |
| id | doaj.art-f90e4a159dbe4cd9a695d8cf5e6ede33 |
| institution | Directory Open Access Journal |
| issn | 2192-8606 2192-8614 |
| language | English |
| last_indexed | 2025-02-18T02:48:03Z |
| publishDate | 2024-01-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Nanophotonics |
| spelling | doaj.art-f90e4a159dbe4cd9a695d8cf5e6ede332024-11-25T11:19:11ZengDe GruyterNanophotonics2192-86062192-86142024-01-0113222923810.1515/nanoph-2023-0728Light-induced modulation of viscoelastic properties in azobenzene polymersChiodini Stefano0Borbone Fabio1Oscurato Stefano L.2Garcia Pablo D.3Ambrosio Antonio4Center for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Via Rubattino 81, 20134, Milan, ItalyDepartment of Chemical Sciences, University of Naples “Federico II”, Via Cinthia Complesso Universitario di Monte Sant’Angelo, Via Cintia, 80126Naples, ItalyCenter for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Via Rubattino 81, 20134, Milan, ItalyBYM-Ingema, Centro de Empresas del Caudal, Polígono Vega de Arriba, 33600, Mieres, SpainCenter for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Via Rubattino 81, 20134, Milan, ItalyPhoto-induced isomerization of azobenzene molecules drives mass migrations in azopolymer samples. The resulting macroscopic directional photo-deformation of the material morphology has found many applications in literature, although the fundamental mechanisms behind this mass transfer are still under debate. Hence, it is of paramount importance to find quantitative observables that could drive the community toward a better understanding of this phenomenon. In this regard, azopolymer mechanical properties have been intensively studied, but the lack of a nanoscale technique capable of quantitative viscoelastic measurements has delayed the progress in the field. Here, we use bimodal atomic force microscopy (AFM) as a powerful technique for nanomechanical characterizations of azopolymers. With this multifrequency AFM approach, we map the azopolymer local elasticity and viscosity, with high resolution, after irradiation. We find that, while in the (previously) illuminated region, a general photo-softening is measured; locally, the Young modulus and the viscosity depend upon the inner structuring of the illuminating light spot. We then propose a possible interpretation based on a light-induced expansion plus a local alignment of the polymer chains (directional hole-burning effect), which explains the experimental observations. The possibility to access, in a reliable and quantitative way, both Young modulus and viscosity could trigger new theoretical–numerical investigations on the azopolymer mass migration dynamics since, as we show, both parameters can be considered measurable. Furthermore, our results provide a route for engineering the nanomechanical properties of azopolymers, which could find interesting applications in cell mechanobiology research.https://doi.org/10.1515/nanoph-2023-0728azopolymernanomechanicsbimodal afmyoung modulusviscosity |
| spellingShingle | Chiodini Stefano Borbone Fabio Oscurato Stefano L. Garcia Pablo D. Ambrosio Antonio Light-induced modulation of viscoelastic properties in azobenzene polymers Nanophotonics azopolymer nanomechanics bimodal afm young modulus viscosity |
| title | Light-induced modulation of viscoelastic properties in azobenzene polymers |
| title_full | Light-induced modulation of viscoelastic properties in azobenzene polymers |
| title_fullStr | Light-induced modulation of viscoelastic properties in azobenzene polymers |
| title_full_unstemmed | Light-induced modulation of viscoelastic properties in azobenzene polymers |
| title_short | Light-induced modulation of viscoelastic properties in azobenzene polymers |
| title_sort | light induced modulation of viscoelastic properties in azobenzene polymers |
| topic | azopolymer nanomechanics bimodal afm young modulus viscosity |
| url | https://doi.org/10.1515/nanoph-2023-0728 |
| work_keys_str_mv | AT chiodinistefano lightinducedmodulationofviscoelasticpropertiesinazobenzenepolymers AT borbonefabio lightinducedmodulationofviscoelasticpropertiesinazobenzenepolymers AT oscuratostefanol lightinducedmodulationofviscoelasticpropertiesinazobenzenepolymers AT garciapablod lightinducedmodulationofviscoelasticpropertiesinazobenzenepolymers AT ambrosioantonio lightinducedmodulationofviscoelasticpropertiesinazobenzenepolymers |