Surface & Coatings Technology 406 (2021) 126727 Available online 4 December 2020 0257-8972/© 2020 Elsevier B.V. All rights reserved. Femtosecond laser surface texturing of polypropylene copolymer for automotive paint applications Ambra Guarnaccio a, * , Claudia Belviso b, * , Pietro Montano b, c , Francesco Toschi e , Stefano Orlando a, * , Gabriele Ciaccio d , Sergio Ferreri d , Dimitri Trevisan d , Donato Mollica a , Giovanni P. Parisi a , Patrizia Dolce a , Alessandro Bellucci e , Adriana De Stefanis e , Daniele M. Trucchi e , Veronica Valentini e , Antonio Santagata a , Francesco Cavalcante b , Antonio Lettino b , Luca Medici b , Pietro P. Ragone b , Vito G. Lambertini d a Istituto di Struttura della Materia - CNR (ISM-CNR), Sede di Tito Scalo, Zona Industriale di Tito Scalo, 85050, PZ, Italy b Istituto di Metodologie per l’Analisi Ambientale - CNR, (CNR – IMAA), Zona Industriale di Tito Scalo, 85050, PZ, Italy c FCA Italy - UNIT ` A PLASTICA, Zona Industriale San Nicola di Melf, 85025 Melf, PZ, Italy d Centro Ricerche FIAT – CRF, Orbassano, TO, Italy e Istituto di Struttura della Materia - CNR (ISM-CNR), Sede di Montelibretti, Via Salaria Km 29,300, 00015 Montelibretti, RM, Italy A R T I C L E INFO Keywords: Polypropylene (PP) Fs laser surface texturing (LST) Scanning Electron Microscopy (SEM) μ-Raman Wettability Paint adhesion tests ABSTRACT Over the past few decades, polymers have progressively replaced metals and metallic alloys in technological applications for which, for example, lightweight, cost-effectiveness, chemical resistance and fexibility for precision-machines components are needed. Furthermore, there is great attention in modifying polymeric sur- faces through physical and/or chemical treatments. In this context, the aim of this study is the enhancement of polypropylene specifc automotive applications by inducing changes into its surface morphologies. Laser surface texturing technique is of particular interest because of its ability in producing morphological and, consequently, physical and/or chemical modifcations on polymer surface. A femtosecond Titanium:Sapphire laser source was employed in order to investigate any variation of surface properties due to the fne tuning of both laser pulse energy and focused laser beam distance from the sample target. The laser treated samples were studied by Scanning Electron Microscopy, μ-Raman spectroscopy and contact angle measurements. The morphological analysis showed that micrometric sized dimple- and groove-like structures were produced after laser irradiation, maintaining mostly unchanged the chemical features of polypropylene surface but changing its wetting prop- erties. These fndings have been successfully applied to activate polypropylene surfaces for subsequent painting processes in automotive industry demonstrating that the femtosecond laser surface treatment here studied is an alternative method to the commonly used fame treatments on automotive components improving the paint adhesion to the treated polypropylene surfaces. 1. Introduction One of the most used techniques producing physical-chemical and morphological modifcations on polymer surface is represented by the laser surface texturing (LST) method, as described in details in the state of the art paper published by Etsion [1]. LST consists of a focused laser beam impinging on a material whose topmost layer absorbs the laser radiation, in this way allowing modifcations to both morphology and chemistry of the surface. It also allows improving the tribological properties of engineered materials as those described in the review recently published by Mao et al. [2] or of polymeric materials designed for biomedical applications as described by Riveiro et al. [3]. In general, the surface’s morphology is modifed by material removal after its heating, melting or vaporization by thermalization of the optical energy due to the energy-releasing laser beam (thermal process). As an example of this heating effect, the paper by Rahaman et al. [4] describes the ultrafast laser interaction with polypropylene surfaces while, the melting or vaporization effect is exploited by Tan et al. [5] by utilising a * Corresponding authors. E-mail addresses: ambra.guarnaccio@pz.ism.cnr.it (A. Guarnaccio), claudia.belviso@imaa.cnr.it (C. Belviso), stefano.orlando@cnr.it (S. Orlando). Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat https://doi.org/10.1016/j.surfcoat.2020.126727 Received 30 September 2020; Received in revised form 1 December 2020; Accepted 3 December 2020