ABSTRACT The continuous growth in the demand of high quality fluoropolymers requires more and more capability of designing and producing polymers with complex polymer chain morphology. Accordingly, a challenge of the modern polymer engineering is to make available new polymerization technologies able to strictly control the polymer microstructure in terms of molecular weight distribution (MWD), branching degree, type and number of chain ends. Along this line, a new polymerization technology, the so-called Branching & Pseudo-living technology (B&P), has been recently developed and patented [1]. In the B&P technology, the polymerization reaction is carried out under pseudo-living conditions by using a iodine containing compound as degenerative transfer agent [2]. During the polymerization reaction, a controlled chain branching mechanism is established by introducing into the reactor small quantities of special highly reactive polyfunctional fluorinated molecules. In this paper, the use of a fluorinated diene of general formula CH2=CH(CF2)nCH=CH2 as polyfunctional molecule able to increase the polymer chain branching is discussed. In order to prevent the formation of gelled fractions, an advanced control procedure of the diene feeding has been assessed [3]. In the first part of this paper it will be shown how the combination of the pseudo-living conditions with the controlled branching mechanism allows a close control of the microstructure of the produced polymer. In particular, by using B&P technology, fluoropolymers with more than two iodine chain ends per macromolecule can be synthesized. This aspect is particularly important because the iodine chain ends are still reactive and can be used as sites for further reactions, such as the synthesis of block copolymers, grafting reactions or peroxide crosslinking. In such a way, polymers with complex molecular architecture can be synthesized to match the in-use properties requested by new application fields. In the second part of the paper, some examples of industrial exploitation of B&P technology will be addressed. First, the assessment of a peroxide curing chemistry of fluoroelastomers by using the iodine chain ends as cure sites will be presented. Then, the use of B&P polymerization for the synthesis of fluorinated thermoplastic elastomers will be discussed.
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