Electron beam induced surface cross-linking of functional monomers coated on silicon substrate Santosh Mahapatra a , Dhananjay Bodas b, ⁎ , A.B. Mandale c , S.A. Gangal b , V.N. Bhoraskar a a Department of Physics, University of Pune, Pune 411 007, India b Department of Electronic Science, University of Pune, Pune 411 007, India c Scientific Instruments Laboratory, Physical Chemistry Division, National Chemical Laboratory, Pune 411 008, India Received 14 October 2005; accepted 10 November 2005 Available online 1 December 2005 Abstract A 3 : 1 composition of functional monomer : multifunctional acrylate was spin coated and later cross-linked under the influence of keV electron irradiation on the surface of silicon to generate a surface-anchored cross-linked network bearing functional moieties. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) as well as wetting angle measurements were used for the analysis of functional monomer cross-linked surfaces. Results of the surface reconstruction of surfaces and electron irradiated on coated silicon wafers reveal that long-term hydrophilic surfaces can be achieved. Thus, the surface architecture can be favorably manipulated by using this remarkable technique with a suitable combination of functional monomers and cross-linkers. © 2005 Elsevier B.V. All rights reserved. Keywords: Electron beam irradiation; Polymers; FTIR; XPS; Surface modification 1. Introduction Polymers have evolved in the past century to become sem- inal materials in a wide variety of industrial, electronic, and research applications. Due to vast area of interest covered by polymers, they obviously become the center of attraction for material scientists. The properties of polymers could be tailored according to the requirement with doping, grafting, cross-link- ing, etc. Due to so many iterations possible, polymers happen to be the most suitable, easy to use, handle, and available material for wide applications. The polymer with different properties at its surface is lately one of the most popular areas of research in polymer chemistry [1–3]. Amongst all the techniques of surface modification, func- tional group implantation using electron irradiation [4] has emerged to be the most rational alternative due to the many obvious advantages including uniform and controlled modifica- tion. However, it is often reported that hydrophilicity functional- ities generated at the polymer interface as a result of electron implantation are temporary and are lost with storage time [5–7]. This phenomenon termed as ‘surface reconstruction’ is the major drawback associated with this technique. This surface dynamics leading to hydrophobic recovery depends on many factors like polymer physio-chemical properties, temperature, storage time and is therefore, a feebly understood complex phenomenon, which differs from one substrate to another [8,9]. The hydropho- bic recovery is determined by an increase in the water contact angle, the rate of which varies with the nature of polymer. The loss of surface functionality with time is the major con- cern of the researcher working in the area of surface modifica- tion. Although, there are a large number of reports on the surface modification of polymers [10], only a few of them have appeared on tailor-made permanently hydrophilic diene-elastomer surfaces [11,12]. The report presented here is a part of our study aimed at fabrication of permanently hydrophilic surfaces via controlled grafting of functional monomers. It is well known that exposure of polymer film to electron irradiation conditions leads to degra- dation and surface cross-linking [13,14]. Taking the advantage of the drawbacks of cross-linked surfaces, we have accomplished deliberate cross-linking of functional monomers (FM) and mul- tifunctional acrylates (MFAs) onto the silicon surface. In the present study, functional vinylic monomers along with functional cross-linkers were spin coated onto the surface of the silicon and Materials Letters 60 (2006) 1360 – 1365 www.elsevier.com/locate/matlet ⁎ Corresponding author. E-mail address: dbodas@lpmo.edu (D. Bodas). 0167-577X/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2005.11.029