Crosslinking radicals

Figure 5.18 Styryl-functionalized chiral salen ligands used in the crosslinking radical suspension polymerization with styrene to generate Mn epoxidation catalysts [71].

Figure 3.73. Volume size of voxels assuming ellipsoid structure as a function of the inverse of the scan speed. The voxels were obtained by TP initiated crosslinking radical polymerization of acrylates in the presence of poly (styrene-co-acrylonitrile) as binder and an amino-substituted distyrylbenzene as TP active initiator using a pulsed laser (150-fs pulses at a 76-MHz repetition rate or 85-fs pulses at a repetition rate of 82 MHz). (From Ref. [133] with permission of the Technical Association of Photopolymers, Japan.)...

Gelation via Noncovalcnt Interactions Gelation via Covalent Crosslinking Radical Chain Polymerization Gelation via... 

The production of free radicals is the driving force for peroxide crosslinking. Radicals are atoms or molecular fragments with unpaired electrons. These radicals cause an unstable situation and react to allow the electron to pair with another. Rubber peroxide crosslinking reaction consists of three basic steps as follows." ... 

The original compound, maleimide (2,5-dioxo-A -pyrroline), is synthesized by the cyclo-condensation of ammonia and maleic acid. Similarly, primary amine is added to maleic anhydride, followed by cyclocondensation, to form N-substituted maleimide (Fig. 2). This reaction is applied to the preparation of bis-maleimides (BMl) [1]. At first, BMI was used as a crosslinking agent for natural rubber (NR). An o-dichlorobenzene solution of NR was crosslinked by BMI at I08-150°C in the presence of peroxides. The radicals generated from peroxides react with the double bonds of both BMI and NR [ 1 ]. 

If (P ) is terminated by a chain transfer to a solvent or a monomer, a graft copolymer is formed, or, if the termination is from a combination, a crosslinked network polymer is formed. If the pre-existing polymer (B) contains an end group that itself is photosensitive (or can produce a radical by interacting with photoinitiator) and in the presence of a vinyl monomer (A), block copolymer of type AB can be produced if the photosensitive group is on one end of the polymeric chain. Type ABA block copolymer can be produced if the polymer chain (B) contains a photosensitive group on both ends. 

When these polymers are subjected to light of A = 365 nm in bulk vinyl monomer, (MMA or styrene) grafted or extensive crosslinking polymers were produced. The photografting or photocrosslinking occurs through the macro-radicals photochemically generated on the backbone of the polymer ... 

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