Surface modification of poly(vinylidene fluoride) by alkaline treatment Part 2. Process modification by the use of phase transfer catalysts G.J. Ross a,1 , J.F. Watts a, * , M.P. Hill a , P. Morrissey b a School of Mechanical and Materials Engineering, University of Surrey, Guildford, GU2 7XH, UK b National Power plc, Harwell International Business Centre, Harwell, Didcot, OX11 0QA, UK Received 5 March 2000; received in revised form 17 April 2000; accepted 19 April 2000 Abstract A detailed study of the alkaline modification of poly(vinylidene fluoride) (PVdF) by a phase transfer catalyst (PTC) medium has been carried out by X-ray photoelectron spectroscopy, (XPS), secondary ion mass spectrometry (SIMS) and Raman spectroscopies, to determine the composition of the modified surface layer. The study indicates the formation of a surface layer consisting of conjugated CyC bonds, concomitant with surface defluorination and the inclusion of oxygen functionalities on treatment. A previous investigation studied the affect of alkaline treatment, however without the use of PTCs (Ross GJ, Watts JF, Hill MP, Morrissey P. Surface modification of poly(vinylidene fluoride) by alkaline treatment. 1. The degradation mechanism Polymer 2000;41: 1695–96.), that produced a surface layer with different functionalities. A mechanism for the degradation process in the presence of a PTC is proposed in this paper, which includes the formation of the polyene structure followed by hydroxide attack to yield hydroxyl and carbonyl groups and more complex oxygen functionalities.  2000 Elsevier Science Ltd. All rights reserved. Keywords: Poly(vinylidene fluoride); Conjugation; Phase transfer catalysts 1. Introduction Surface treatment of poly(vinylidene fluoride) (PVdF) with concentrated sodium hydroxide, increases its resis- tance to attack by other harsh caustic environments. Although this is an effective treatment, it can take many hours to complete, which is far too long to be implemented as a commercial process. There have been a few studies [2] indicating that the process can be accelerated by the use of phase transfer catalysts (PTCs), with sodium and potassium hydroxides [3–5]. This paper sets out to expand the data presented in the literature, and compare the results with that of samples treated with concentrated sodium hydroxide [1]. According to the original definition [6], phase transfer catalysis accelerates or permits reactions between ionic compounds and organic, water insoluble, substrates in solvents of low polarity. Such catalysts are typically onium salts, which readily solubilize alkali metal ions. The basic function of the catalyst is to transfer anions of the reacting salt into the organic medium in the form of ion pairs. As a result of the nature of the catalysts, the activity is strongly related to the hydrophilic-hydrophobic balance, i.e. the distribution of the catalyst between the aqueous and organic phase. Therefore the solvophobic nature of the polymer is considered to affect the ability of the catalyst. Cho and Song [2] used Fourier transform infrared (FT-IR) and ultra-violet (UV–VIS) spectroscopy to investigate the reaction mechanism, and proposed the following for the PTC assisted alkaline modification of PVdF: Owen et al. [7,8] investigated the surface modification of PVC, and Kise and Ogata investigated the surface modifica- tion of PVdF [3]. Both concluded that CyC double bonds were almost exclusively formed in a conjugated manner; Kise and Ogata suggested that triple bonds were also formed. Dias and McCarthy [4] and Hahn and Percec [9] also reported the formation of double and triple bonds with no apparent oxygen incorporation, with alkaline treatment of PVdF, the experiments were carried out under vacuum Polymer 42 (2001) 403–413 0032-3861/01/$ - see front matter  2000 Elsevier Science Ltd. All rights reserved. PII: S0032-3861(00)00328-1 www.elsevier.nl/locate/polymer * Corresponding author. Tel.: +1483-259617; fax: +1483-259508. E-mail address: j.watts@surrey.ac.uk (J.F. Watts). 1 Current address: Department of Materials Science and Engineering, University of Cincinnati, USA.