Initial reactive agents

Current thinking and most research efforts are based on the belief that the pathogenesis of the reactions involves bioactivation of the sulfonamide, forming reactive metabolites that act as the initial reactive agents in a sequence of interactions that ultimately lead to the patients ... 

Such functionality can also be of great practical importance since functional initiators, transfer agents, etc. are applied to prepare end-functional polymers (see Section 7.5) or block or graft copolymers (Section 7.6). In these cases the need to maximize the fraction of chains that contain the reactive or other desired functionality is obvious. However, there are also well-documented cases where weak links formed by initiation, termination, or abnormal propagation processes impair the thermal or photochemical stability of polymers. 

New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers) End Reactive Polyisobutylenes by Semicontinuous Polymerization... 

B = 1. In this case, the reaction follows the uniform conversion model [31], which indicates that it proceeds under chemical reaction control, and the reactive agent first diffuses through the pore network and later reacts at any internal active site. The particle will retain its initial size during the conversion... 

By considering Equation 4.4, obviously the rate of increase in the cure reaction is a function of the amount of reactive agent remaining in the rubber at the time of removal from the mold. This is the reason why the increase in the state of cure is higher at the mid-plane of the rubber sheet where the initial value of the state of cure is lower, viii. The main parameters of the postcure system are the nature of the fluid, its temperature, and the value of the coefficient of thermal transfer at the rubber-fluid interface. 

In this process, no reactive agents are added to the core material polymerization occurs exclusively in the continuous phase and on the continuous phase side of the interface formed by the dispersed core material and continuous phase. Initially, a low-molecular-weight prepolymer will be formed as time goes on, the prepolymer grows in size, and it deposits on the surface of the dispersed core material, thereby generating a solid capsule shell. 

Table 3.11, the low reactivity of the sulfur-centered radical should be noted as it does not react with vinyl monomers to initiate kinetic chains but rather acts as a terminator of the growing chains. An initiator behaving in this way is termed an iniferter (initiator-transfer-agent-terminator) (Scheme 3.12) [47,48]. 

Methoxydimethylsulfonium and Trimethylsulfoxonium Salts. Alkylating agents react with DMSO at the oxygen. For example, methyl iodide gives methoxydimethylsulfonium iodide (10) as the initial product. The alkoxysulfonium salts are quite reactive and, upon continued heating, either decompose to give carbonyl compounds or rearrange to the more stable trimethylsulfoxonium salts, eg, (11) (eq. 21) (52) ... 

Simplified nitrile mbber polymerization recipes are shown in Table 2 for "cold" and "hot" polymerization. Typically, cold polymerization is carried out at 5°C and hot at 30°C. The original technology for emulsion polymerization was similar to the 30°C recipe, and the redox initiator system that allowed polymerization at lower temperature was developed shortiy after World War II. The latter uses a reducing agent to activate the hydroperoxide initiator and soluble iron to reactivate the system by a reduction—oxidation mechanism as the iron cycles between its ferrous and ferric states. 

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