Preparation of Light-responsive Membranes by a Combined Surface Grafting and Postmodification Process |
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Authors: | Katrin Sch?ller Lukas Baumann Dirk Hegemann Damien De Courten Martin Wolf René M Rossi Lukas J Scherer |
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Institution: | 1.Laboratory for Protection and Physiology, Empa, Swiss Federal Laboratories for Materials Science and Technology;2.Laboratory of Advanced Fibers, Empa, Swiss Federal Laboratories for Materials Science and Technology;3.Division of Neonatology, University Hospital Zurich |
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Abstract: | In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is presented. The polymerization from the membrane surface is induced by plasma treatment of the membrane, followed by reacting the membrane surface with a methanolic solution of 2-hydroxyethyl methacrylate (HEMA). Special attention is given to the process parameters for the plasma treatment prior to the polymerization on the surface. For example, the influence of the plasma-treatment on different types of membranes (e.g. polyester, polycarbonate, polyvinylidene fluoride) is studied. Furthermore, the time-dependent stability of the surface-grafted membranes is shown by contact angle measurements. When grafting poly(2-hydroxyethyl methacrylate) (PHEMA) in this way, the surface can be further modified by esterification of the alcohol moiety of the polymer with a carboxylic acid function of the desired substance. These reactions can therefore be used for the functionalization of the membrane surface. For example, the surface tension of the membrane can be changed or a desired functionality as the presented light-responsiveness can be inserted. This is demonstrated by reacting PHEMA with a carboxylic acid functionalized spirobenzopyran unit which leads to a light-responsive membrane. The choice of solvent plays a major role in the postmodification step and is discussed in more detail in this paper. The permeability measurements of such functionalized membranes are performed using a Franz cell with an external light source. By changing the wavelength of the light from the visible to the UV-range, a change of permeability of aqueous caffeine solutions is observed. |
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Keywords: | Bioengineering Issue 85 plasma-induced polymerization smart membranes surface graft polymerization light-responsive drug delivery plasma modification surface-initiated polymerization permeability |
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