Polymeric membranes surface modification

Polymeric Membranes Surface Modification by Grafting to Method and Fabrication of Multilayered Assemblies... 

This type of surface modification, if adequate functional groups are used, can be useful in incorporating silica particles into polymeric matrices (e.g., into rubber for tires) or in increasing the hydrolytic stability of high-surface-area silica (e.g., that used for membranes). Surface modification of silica is a very important principle and is widely commercialized. 

Wavhal DS and Fisher ER, Membrane surface modification by plasma-induced polymerization of acrylamide for improved surface properties and reduced protein fouling, Langmuir 2003,19, 79-85. 

Lopez-Perez, P.M., Marques, A.P., da SUva, R.M.P., Pashkuleva, I. and Reis, R.L. 2007. Effect of chitosan membrane surface modification via plasma induced polymerization on the adhesion of osteoblast-like cells. 

Chapter 7 examines the use of plasma treatment for the modification of polymeric membranes. Plasma treatment is carried out at the manbrane surface so that the beneficial properties of the bulk material remain unchanged. Surface properties such as roughness and functionality can be altered to improve the performance of the membrane. All these processes are very quick and the time taken for modification is usually a few seconds up to a few minutes. The method uses chemicals in the gaseous form and produces very small amounts of wastes. Among all techniques of membrane surface modification, plasma treatment seems to be the most versatile and environment-friendly. The authors of Chapter 7 discuss how these benefits impact on membrane modification strategies. 

WAV 02] Wavhal D.S., Fisher E.R., Membrane Surface Modification by Plasma-Induced Polymerization of Acrylamide for Improved Surface Properties and Reduced Protein Fouling , Langmuir, vol. 19, pp. 79-85, 2003. 

In a previous section, the effect of plasma on PVA surface for pervaporation processes was also mentioned. In fact, plasma treatment is a surface-modification method to control the hydrophilicity-hydrophobicity balance of polymer materials in order to optimize their properties in various domains, such as adhesion, biocompatibility and membrane-separation techniques. Non-porous PVA membranes were prepared by the cast-evaporating method and covered with an allyl alcohol or acrylic acid plasma-polymerized layer the effect of plasma treatment on the increase of PVA membrane surface hydrophobicity was checked [37].The allyl alcohol plasma layer was weakly crosslinked, in contrast to the acrylic acid layer. The best results for the dehydration of ethanol were obtained using allyl alcohol treatment. The selectivity of treated membrane (H20 wt% in the pervaporate in the range 83-92 and a water selectivity, aH2o, of 250 at 25 °C) is higher than that of the non-treated one (aH2o = 19) as well as that of the acrylic acid treated membrane (aH2o = 22). 

A wide variety of polymeric membranes with different barrier properties is already available, many of them in various formats and with various dedicated specifications. The ongoing development in the field is very dynamic and focused on further increasing barrier selectivities (if possible at maximum transmembrane fluxes) and/ or improving membrane stability in order to broaden the applicability. This tailoring of membrane performance is done via various routes controlled macro-molecular synthesis (with a focus on functional polymeric architectures), development of advanced polymer blends or mixed-matrix materials, preparation of novel composite membranes and selective surface modification are the most important trends. Advanced functional polymer membranes such as stimuli-responsive [54] or molecularly imprinted polymer (MIP) membranes [55] are examples of the development of another dimension in that field. On that basis, it is expected that polymeric membranes will play a major role in process intensification in many different fields. 

Graft copolymers combine the properties of their polymeric constituents and as such are polymer alloys, which open a vast field of new polymeric species. This is why active research along these lines is performed in many academic and industrial research laboratories all over the world. However, only few applications have reached a commercial level today. They involve the production of specific polymeric adhesives, perm-selective membranes, bio-medical devices and the surface modification of certain products. 

Theoretical Model of Modification of Polymer Membrane Surfaces in After-Glow of Oxygen-Containing Plasma of Non-Polymerizing Gases Lame Equation... 

---