Crosslinking techniques

The majority of hydrophilic and water-soluble polymers are manufactured on the commercial level. Their list includes PAAm, copolymers of AAm, PAAc, PEO, PVA, poly(jY-vinylpyrrolidone), some polyamines etc. So, it seems practically highly attractive to produce hydrogels based on these polymers using various crosslinking techniques. 

Interaction with plurivalent cations via ligand exchange mechanism is one more rather widely applied crosslinking technique. The network bonds of ionic or donor-acceptor nature are located, with respect to lifetime, between the truly covalent crosslinks and physical entanglements. Generally speaking, gelation in these systems is reversible. 

Seko, N., Tamada, M. and Yoshii, F. (2005) Current status of adsorbent for metal ions with radiation grafting and crosslinking techniques. Nuclear Instruments and Methods in Physics Research, Section B Beam Interactions with Materials and Atoms, 236(1-4), 21-29. 

Vasudev. S.C, and Chandy. T, Effect of alternative crosslinking techniques on the enqrmatic degradation of bovine pericardia and their calcification, J. Biomed. Mater. Res., 35,357-369 (1997). 

Fig. 1 Nanofiber modification strategies. In step 1, many polymer and solution properties will affect the size, stability, and reactivity of nanofihers in the final mat, including multipolymer blending strategies, incorporation of soluble factors/drugs/spheres, and/or loading concentrations. In step 2, during spinning, the ambient conditions and voltage applied must be tailored for each polymer source and can be dictated by the nature of the collector or the number of jets employed simultaneously. In step 5, the as-spun mat can be modified by various crosslinking techniques to stabilize the polymers or, in the case of soluble or carrier polymers, these can be leached out by subsequent liquid washes...

The crosslinking technique forms a PFB/F8BT bilayer with a well-defined interface, and was shown to have a negligible effect on the transport properties as well as the PL and EL emission spectra of the PFB [61], Single-layer, PFB-only and polymer blend LEDs were produced by spin coating 170-nm films from common chloroform solution onto a PEDOTPSS / ITO substrate. For all devices, cathodes were formed by thermal evaporation of Ca (60 nm) and encapsulated with a thick A1 overlayer. 

Both in vimi and in vivo tests with rats demonstrated the artificial cells were effective blood oxygenators and loterated by the animals. The efficiency of oxygenation was somewhat lower than human blood (Table 19.4-5). However, Davis, Asher, and Wallace feel this can be improved by refining ibe crosslinking technique. 

Accelerated-sulfur vulcanization is the most widely used method. For many applications, it is the only rapid crosslinking technique that can, in a... 

A crosslinking technique, based on the use of thermoplastic/block copolymers discussed in Section 1.5, has recently been developed for limiting flow at high extensions. 

Lin H, Zhao C, Jiang Y, Ma W, Na H (2011) Novel hybrid polymer electrolyte mranbranes with high proton conductivity prepared by a silane-crosslinking technique for direct methanol fuel cells. J Power Sources 196 1744—1749... 

Dudley, C.N., Schoberl, B., Sturgill, G.K., Beckham, H.W. and Rezac, M.E. 2001. Influence of crosslinking technique on the physical and hansport properties of ethynyl-tenninated monomer/polyetherimide asymmehic membranes, 191 1-11. 

Yoshii, F., Suhattini, M., Sagasawa, N., Mitomo, H., Kume, T. Modification of biodegradable polymers by radiation crosslinking technique with polyfunctional monomers. Nucl. Instrum. Meth. Phys. Res. B 208, 370-373 (2(X)3)... 

T. A. Ahmed, and M. Khalid, Development of alginate-reinforced chitosan nanoparticles utilizing W/O nanoemulsification/internal crosslinking technique for transdermal delivery of rabeprazole. Life Sci., 110 (1), 35-43, 2014. 

George, S., Kumari, P., and Urmikrishnan, G.P. (2010) Influence of static and dynamic crosslinking techniques on the transport properties of ethylene propylene diene monomer rubber/poly (ethylene-co-vinyl acetate) blends./. Polym. Res., 17, 161-169. 

All of the reported crosslinking techniques are very efficient and generate robust phase-separated nanostructures (Figure 17.8) (Read and Armes, 2007). The stabilization methodologies all allow for the complete protection of the core or bilayer domain by the uniform stabilized shell layer, while maintaining the desired nanoscale particle diameters with narrow size distributions (with distributions of around 1-5 nm) - thus providing a confined environment within the core or bilayer domain in which reagents can be sequestered. 

Microspheres are generally prepared by emulsion solvent evaporation, spray drying and chemical crosslinking techniques. 

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