Polymer grafting photo-initiated

Using an intrinsic photo-reactivity of the support polymer (see Scheme 4d) is an alternative for initiation of a surface imprinting polymerization without an added photo-initiator. This grafting-from approach offers the highest surface selectivity of initiation, but it is limited to a few polymers. In first experiments with polysulfone, the imprinting efficiency had been rather low [77b]. 

Yang H, Lazos D, Ulbricht M. Thin, highly crosslinked polymer layer synthesized via photo-initiated graft copolymerization on a self-assembled-monolayer-coated gold surface. J Appl Polym Sci 2005 97 158-164. 

Gkacintov, N., V. Stannett, and E. W. Abrahamson The photo-initiated grafting of vinyl monomers to cellulose and other polymers using anthra-quinone vat dyes. Makromol. Chem. 36, 52 (1959). 

Kochkodan et al. [76] had found that thin MIP layers could be prepared via a controlled polymer deposition process at low monomer conversion, using the very fast photoinitiation of a cross-linking polymerization by a-scission photo-initiator such as benzoin ethylether which had been previously coated on the surface (see Scheme 4b). This had been investigated with porous membranes as matrix which had been functionalized very evenly (see Fig. 1). With the macroporous MIP composite membranes, the membrane pore size could be used to probe grafted layer thickness, as shown by data from permporometry (see Fig. 2). For the same range of coverage with a cross-linked polyacrylate/acrylamide—estimated... 

Piletsky et al. [81] had found that using a coated hydrogen abstraction photoinitiator (see Scheme 4e) very thin MIP films, which were covalently anchored and covered the entire surface of the base material, could be synthesized by a photo-initiated cross-linking graft copolymerization. This approach had been first explored with benzophenone as photo-initiator and a membrane from polypropylene as support. MIP synthesis and recognition were possible in/from water, and significantly less cross-linker than with bulk preparations was necessary to obtain the highest template specificity. Both effects were explained by a contribution of the soUd polymer support to the stabilization of the imprinted sites. The approach is very flexible because no premodification is necessary. 

The surface of PEEK can be protected by a hydrophilic high density nanometer-scaled layer on the surface by the photoinduced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine. Photo-initiators are not needed, the reaction is a self-initiated surface graft polymerization. Actually, the diphenylketone moiety in the PEK polymer backbone acts as a photo-initiator similar to benzophenone. Since the photoinduced polymerization occurs only at... 

Polymer surface modifications can be performed either by simultaneous grafting or by postirradiation grafting. In the first case, the polymer surface is covered by the monomer and the photo-initiator. In the second case, the activation of polymer surface occurs after the irradiation of the grafting photoinitiators (at the polymer surface), thus, generating initiators which are able to initiate monomer polymerization. 

PAN 04] Pan B., Viswanathan K., Hoyle C.E. et al, Photo initiated grafting of maleic anhydride onto polypropylene . Journal of Polymer Science Part A Polymer Chemistry, vol. 42, pp. 1953-1962, 2004. 

TRCSs prepared by a photo-initiator or photo-cross-linker-induced polymer grafting method... 

Thin fQm of molecularly imprinted polymer can be prepared on a SPR chip, and the specific binding activity can be monitored as a change in angle for tight reflected from the chip. However the preparation of molecularly imprinted polymer on the chip requires often a careful control of polymer composition. The most common method involves the free radical polymerization with the use of a photo-initiator, and this process can lead to changes of template structure in the case of proteins their denaturation occurs. Other preparation procedures of molecularly imprinted polymers for SPR are atom transfer radical polymerization and polymer grafting method these methods provide a better control of the film physical characteristics, but require a suitable catalyst for polymerization. 

To reduce the formation of undesired homopolymer and cross-linked or branched polymer in the grafting-from approach with an initiator, a photo-induced living graft polymerization method for surface membrane modification was proposed by Ma et al. [70]. In the first step, BP abstracts hydrogen from the substrate to generate surface radicals and semipinacol radicals, which combine to form surface photoinitiators in the absence of monomer solutions (Figure 18.5). In the subsequent step. 

H. Kubota, 0. Ogiwara, K. Natsuzaki Photo-induced cellulose radicals capable of initiating graft-copolymerization//./. Polym. Sci. Polym. Chem. Ed. (1974), V. 12, 67-80. 

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