Styrene RTCP

Phenoxyl radicals (Ph-0 ) are known not to iiutiate radical polymerization in most cases (2) and may be RTCP catalysts if they can activate Polymer-I. Based on this idea, we attempted to use phenol derivatives as catalysts, thus extending the element of the catalyst to O (Figure 1). Notably, the phenols include common antioxidants for foods and resins and natural compounds such as vitamins (Figure 1). Their commonness (hence cheapness) and environmental safety may be highly attractive for practical applications. In this paper, we will present the results of the styrene and methyl methacrylate (MMA) polymerizations, along with a mechanistic study. 

As noted above, RTCP is supposed to involve the RT process. If RT exists, the catalyst radical (A in Scheme lb) is mediated and the propagating species is a free radical (Polymer in Scheme lb). Thus, we attempted to detect A by ESR and confirm the free radical nature from the tacticity of the product polymer in the styrene polymerizations with TI (deactivator) and BHT (precursor). 

Alcohols (phenols, a vinyl alcohol, and an iodide derivative (Tl)) worked as effective catalysts for the RTCPs of styrene and MMA. The existence of RT was strongly indicated by the two experiments. Attractive features of the alcohol catalysts include their high reactivity (a small amount being required), low or no toxicity, low cost (cheapness), insensitivity to air (robustness), and minor color and smell. 

RTCP is a simple and robust polymerization indudrng, like iodide-mediated polymerization, a monomer, an alkyl iodide as a dormant spedes (X=I), and a conventional radical initiator as a source of P", along with a catalyst such as Geld as a deactivator (AX). It is applicable to, for example, styrene, methacrylates, AN, and the rdevant functional monomers. Mechanistically, it is based on RT with a minor contribution of DT. 

The RTCP system contains a monomer, an aUcyl iodide dormant species, a coti-ventional radical initiator as radical source, and an organic catalyst [30-35]. The component is ITP including a catalyst. In ITP, the Cex value is relatively small, and thus the dispersity control is limited in many case (e.g., Cex = 4.0 for styrene at 60 C [63] and 1.6 for MMA at 90°C [64]). The addition of a catalyst in RTCP dramatically improves the control of dispersity. 

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