GRAFT POLYMERISATION

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Type AD-G is used in an entirely different sort of formulation. The polymer is designed for graft polymerisation with methyl methacrylate. Typically, equal amounts of AD-G and methyl methacrylate are dissolved together in toluene, and the reaction driven to completion with a free-radical catalyst, such as bensoyl peroxide. The graft polymer is usually mixed with an isocyanate just prior to use. It is not normally compounded with resin. The resulting adhesive has very good adhesion to plasticised vinyl, EVA sponge, thermoplastic mbber, and other difficult to bond substrates, and is of particular importance to the shoe industry (42,43). 

The common feature of these materials was that all contained a high proportion of acrylonitrile or methacrylonitrile. The Vistron product, Barex 210, for example was said to be produced by radical graft copolymerisation of 73-77 parts acrylonitrile and 23-27 parts by weight of methyl acrylate in the presence of a 8-10 parts of a butadiene-acrylonitrile rubber (Nitrile rubber). The Du Pont product NR-16 was prepared by graft polymerisation of styrene and acrylonitrile in the presence of styrene-butadiene copolymer. The Monsanto polymer Lopac was a copolymer of 28-34 parts styrene and 66-72 parts of a second monomer variously reported as acrylonitrile and methacrylonitrile. This polymer contained no rubbery component. 

Graft-polymerisation with Cationic Catalysts, P.H. Plesch, Chemistry and Industry, 1958, 954. 

Chen, R. and Kokta, B.V. (1982). Graft copolymerisation of lignosulphonate with methacrylic acid and acrylate monomers. In Graft Polymerisation of Lignocellulosic Fibers, Hon, D.N.S. (Ed.). ACS Symposium Series, 187, pp. 285-299. 

Hill, C.A.S. and etin, N.S. (2000). Surface activation of wood for graft polymerisation. International Journal of Adhesion and Adhesives, 20, 71-76. 

Philippou, J.L., Johns, W.E. and Nguyen, T. (1982). Bonding wood by graft polymerisation. The effect of hydrogen peroxide concentration on the bonding and properties of particleboard. Holzforschung, 36(1), 37-42. 

In principle block copolymers can also be produced by irradiating solutions containing a homopolymer (from monomer type A) and a monomer (type B) (Fig. 5.34). In such cases, polymerisation resembles that of graft polymerisation where the monomer (B) is thought to be initiated by the macroradical produced by the ultrasonic degradation of the homopolymer. In those cases where polymer was deliberately absent, polymerisation was either not observed to occur or proceeded at a similar rate to that in the presence of polymer. 

The foamed, non-crosslinked resin particles, which have a bulk density of not greater than 0.045 g/cu.cm. and an average cell diameter of at least 200 pm, include PP to which a vinyl comonomer is graft polymerised in such an amount that the weight ratio of the PP to the graft polymer of the vinyl comonomer is in the range of 97 3 to 65 35. They are produced by graft polymerisation at a... 

In the early 1970s, surface modification of most polymers was achieved using redox initiators. Ce+4-induced initiation was employed to achieve surface grafting of acrylamide onto LDPE film [117]. The film was first oxidised by chromic acid and then reduced with diborane to form a hydroxyl-rich surface which was then used to initiate graft polymerisation of acrylamide using Ce+4/HN03. The mechanism of chromic-acid-facilitated surface oxidation of LDPE surface is shown in Scheme 6a and that of free-radical generation is represented in Scheme 6b. 

Cellulose can be replaced by starch or even proteins (Bhattacharya et al, 1997). Of course, it is possible to carry out other graft-polymerisation reactions on cellulose or starch, for instance with acrylic monomers. The obtained material is useful, but it lacks biodegradability due to the synthetic side chains. 

Figure 5.26 Representation of the nanocomposite formed by graft-polymerisation of caprolactone on cellulose...

Tsafack, M.J. and Levalois-Griitzmacher, J. 2006. Plasma-induced graft-polymerisation of flame retardant monomers onto PAN fabrics. Surf Coat Tech., 200 3503-3501. 

Alternating copolymers may be considered as homopolymers with a structural unit composed of the two different monomers. Random copolymers are obtained from two or more monomers, which are present simultaneously in one polymerisation reactor. In graft polymerisation a homopolymer is prepared first and in a second step one or two monomers are grafted onto this polymer the final product consists of a polymeric backbone with side branches. In block copolymerisation one monomer is polymerised, after which another monomer is polymerised on to the living ends of the polymeric chains the final block copolymer is a linear chain with a sequence of different segments. 

Azizov U., Mirkamilov, I., Usmanov, Kh. Radiation Graft Polymerisation, Tashkent, Rap. 1976 (in Russian)... 

By polymer mixture Graft polymerisation. Bicomponent fibres. Fibres from polymer mixture. 

Antimicrobial activity is imparted to the surface(s) of an apparatus or article by polymerising tert-butylaminoethyl methacrylate in the presence of the apparatus or article to achieve adhesion of the polymer to the surface(s). The antimicrobial monomer is preferably graft polymerised on the surface(s). 

Instantly after plasma treatment, the LDPE foil is immersed in an aqueous solution of acrylic acid (AA) (10 vol%) and sodium metabisulfite (0.1 wt%) for 24 h at 30 °C, in order to initiate the radical graft polymerisation of AA onto the activated surface. Following AA polymerisation, polyacrylic acid (PAA) brushes are created on the LDPE surface which are suitable for binding antibacterial agents. To remove weakly bound PAA and unreacted AA species on the surface, the grafted foils should be washed with deionised water at 30 °C. 

Sergeyeva, T.A. Matuschewski, H. Piletsky, S.A. Bendig, J. Schedler, U. Ulbricht, M. Molecularly imprinted polymer membranes for substance-selective solid-phase extraction from water by surface photo-grafting polymerisation. J. Chromatogr. 

Martinez-Hernandez, A.L., Santiago-Valtierra A. L., Alvarez-Ponce M. J., (2008), Chemical modification of keratin biofibres by graft polymerisation of methyl methacrylate using redox initiation. Materials Research Innovations, Vol. 12, No. 4, (December 2008), pp 184-191, ISSN 1432-8917. 

The Mn2(CO)io complex has been recently applied as the photoinitiator to the visible-light-induced surface grafting polymerisation on Au surfaces. This new method, being more rapid than traditional grafting polymerisation processes, may have potential applications in the design of functional interfaces. ... 

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