Water-crosslinking reaction

The different possible adducts formed between mitomycin C and DNA have been isolated by degradation of DNA after in vitro alkylation/crosslinking reactions and structurally characterized. Monoadduct 21 (Scheme 11.3), derived from alkylation at C-l only [53], and monoadducts 22 [54] and 23 [55, 56] (derived from C-10 alkylation by 16 at N-7 or N-2 of guanine, respectively) have been isolated, together with bisadducts 24 [57] and 25 [58], derived from interstrand and intrastrand crosslinks, respectively, and adduct 26 [59], formed by addition of a molecule of water to C-10 instead of the second guanine. All of these adducts have also been isolated from DNA after in vivo crosslinking [60, 61]. 

There are reactive softeners, some of which are N-methylol derivatives of long-chain fatty amides (10.241) while others are triazinyl compounds (10.242). The N-methylol compounds require baking with a latent acid catalyst to effect reaction, whereas dichloro-triazines require mildly alkaline fixation conditions. The N-methylol compounds are sometimes useful for combination with crease-resist, durable-press, soil-release and water-repellent finishes. In this context, the feasibility of using silane monomers such as methyltri-ethoxysilane (10.243), vinyltriethoxysilane (10.244), vinyl triace tylsilane (10.245) and epoxypropyltrimethoxysilane (10.246) in crosslinking reactions to give crease-resist properties and softness simultaneously has been investigated [492]. 

Most of these PEG crosslinkers come as thick, sticky, viscous liquids or low melting solids (PEG2). For this reason, weighing out a small sample of a compound can be difficult or impossible. It usually is best to dissolve an entire vial or a larger amount in organic solvent at a known concentration to permit accurate dispensing of a smaller amount into a reaction. Suitable solvents to prepare a stock solution include dry (molecular sieved) DMSO, DMF, DMAC, acetonitrile, or methylene chloride (for non-water-miscible reactions). 

The crosslinking reaction per se is exothermic, while a corresponding evaporation of water formed consumes heat. 

This paper describes the successful synthesis and examination of polyfr-(amino /9-thiosulfate) ether] (PATE), a water soluble photolabile polymer. Evidence has been presented that the PATE polymer is zwitterionic and forms weak associations in aqueous solutions. Heat treatment of PATE films result in extensive crosslinking, presumably through a disulfide bond. This work presents strong evidence that PATE is activated by deep UV radiation, and that a disulfide crosslink is formed. Sensitization experiments demonstrate that the crosslinking reaction can be induced by a triplet sensitizer. Finally, preliminary results point out the potential for application of PATE films as active photoimaging systems. 

This means that the time for flow-out of the powder becomes shorter with increasing functionality of the crosslinker, with respect to the total cycle time required for reaching satisfactory film properties (mechanical, chemical. Fig. 20, step D). The reduced flow-phase time results in a poorer film surface quality. Moreover, when volatiles are set free as a result of the crosslinking reaction, in this case water, they will cause blister formation after the gel-point. Blister for-... 

As described in Sect. 4.2.1 foamed polyurethanes can be obtained especially through the so-called water-crosslinking of suitable polyol/diisocyanate combinations. Carbon dioxide liberated during the reaction partially causes the expansion of the foam. For a number of reasons additional foaming agents (in the form of low-boiling liquids or CO2) are added in practice, i.e., in order to vary the foam density and the pore size. 

Thixotropic agent Undergo reversible crosslinking reactions via hydrogen bridge bonds, forming a gel structure Added as the last ingredient in the formulation. Mainly used for water-based acrylics... 

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