Plasma-Initiated Grafting

Plasma-initiated polymerization of grafting can be carried out by using polymerizing gases and precursors like fluorocarbons, hydrocarbons and silicone containing monomers (Fig. 3.1). Carrier gas plays important roles in these plasma-surface interactions, and usually inert gas like helium or argon is used as carrier gases [27]. 

---

It is noteworthy that a similar result—a higher level of grafting to the EPR component— had been obtained by other authors (58) who investigated plasma-initiated grafting of polystyrene to PP/EPR blends. This was explained (58) by a high degradation rate of PP, which causes fast ruin of reactive centers in the PP phase. 

The graft copolymerization of many monomers onto cellulose and onto cellulose derivatives has been carried out by different methods that can be generally classified into three major groups (i) chemical methods, (ii) radiation-induced grafting, and (iii) plasma-initiated grafting [11]. 

Yu et al. (2006) used air plasma-initiated grafting of polyvinylpyrrolidone (PVP) in attempts to reduce the PP membrane fouling in an SMBR. It was shown that after continuous operation for about 50 h, the flux recovery, reduction of flux, and relative flux ratio for the modified membranes were 53% higher, 17.9% lower, and 79% higher, respectively, than those for the unmodified membranes. The water contact angle on the PVP-immobilized membrane showed a minimum value of 72.3°, approximately 57° lower than that on the unmodified one. 

Gancarz, L, Bryjak, M., Kunicki, J. and Ciszewski, A. 2010. Microwave plasma-initiated grafting of acrylic acid on Celgard 2500 membrane to prepare alkaline battery separators -Characteristics of process and product. J. Appl. Polym. Sci. 116 868-875. 

Plasma-Initiated Grafting and Initiated Chemical Vapor... 

Gancarz et al. [90] compared the three different approaches to modify PS membranes with AA through plasma-initiated graft polymerization (1) grafting in solution, the plasma-treated polymer membrane was exposed to air for 5 min and dipped into a deaerated aqueous solution of monomer (2) grafting in vapor phase, when Ar plasma treatment on polymers was completed, a monomer vapor was introduced into the chamber and (3) plasma polymerization of monomer vapors in a plasma reactor. It was shown that modified PS membranes prepared in a vapor phase possessed the highest flux. 

V.N. Vasilets, G. Hermel, U. Konig, C. Werner, M. Muller, F. Simon, K. Grundke, Y. Ikada, H.J. Jacobasch, Microw/ave CO2 plasma-initiated vapour phase graft polymerization of acrylic acid onto polytetrafluoroethylene for immobilization of human thrombomodulin. Biomaterials 18 (1997) 1139-1145. 

Modification of Textile Fibers. The reaction of hydrophobic chemicals with textile fibers offers the possibUity of permanent repeUency without alteration of the other physical properties of fibers. However, the disadvantages caused by complex processing, and resultant higher costs of carrying out chemical reactions on fiber in commercial textile plant operations, have limited the commercial appHcations. The etherification and esterification of ceUulose have been most effective in terms of achieving durable water repeUency (32,33). Radiation grafting of reactive repeUents onto fibers has been studied as a potential commercial process (34,35), as has modification by plasma polymerization of gas monomers or plasma initiated polymerization of Hquid monomers (36). 

A composite structure was prepared consisting of a porous substrate memlnnne on which methacrylic acid (MAA) was graft-polymerized by the method of plasma-initiated pol3unerization. Using this type of membrane, an ective binding of metal ions is performed by chelation of di- and trivalent metal ioiK [190]. A pronounced... 

Besides chemical treatment with chlorosulfonic acid, sulfonic groups can be introduced by plasma-initiated surface grafting using sodium styrene sulfonate. " The introduction of ionic groups increases the surface polarity and thus the water permeation. 

Based on the membrane surface properties and the HA properties, various researchers have attempted to change the membrane surface characteristics by surface modification. Different techniques have been performed, such as ion beam irradiation, plasma treatment, redox-initiated graft polymerization, photochemical grafting, and interfacial polymerization (IP). In this chapter, two surface modification techniques, IP and photochemical grafting, are discussed by means of experimental examples. The surface characteristics of the unmodified membrane and the modified membranes are studied and their relationships with irreversible fouling and NF performance are reported. 

---