Radicals and Polymers

Abstract

This article describes some selected results of my 30 years as an industrial researcher. During this time, I had the chance to work on many very different projects. About two thirds of them were dealing with the fascinating interaction of radicals and polymers. Of the more than 350 million tons of industrial polymers produced worldwide every year, about 50% are made by the radical polymerization of monomers that are often stabilized against undesired premature polymerization by addition of polymerization inhibitors. Stabilizers are necessary to protect the majority of polymeric materials during their service life from radical degradation processes triggered by oxygen, heat or light. Modification of the polymeric architecture can be easily achieved via radical polymer analogous reactions. One of the most important developments in polymer science in the last 25 years is controlled radical polymerization. Recently, radical bearing redox-active polymers emerged as promising in energy storage applications, for example, in organic radical batteries. Our contributions to the fields mentioned above are described with examples of: a) novel benzofuranone stabilizers for polymers; b) the serendipidous discovery of novel dyestuffs; c) eco-friendly polymerization inhibitors; d) novel nitroxides and alkoxyamines for the first industrial realization of controlled radical polymerization; e) novel and safe radical initiators; f) nitroxide radicals bearing polymers for electrochemical applications.

Mechanistic Insights into N-Acyloxyamine-Initiated Controlled Degradation of Polypropylene: The Unexpected Role of Keto–Enol Tautomerization in Carboxylate Radical Chemistry

“…Arguably, the most important industrial application of this class of initiators is for controlled degradation of polypropylene (PP) . For this application, a tailor-made compound has been developed and commercialized under the trade name Irgatec CR 76 (see Scheme ), which is used as a safe, nonexplosive alternative to the explosive and fire supporting peroxides normally used for controlled degradation processing.…”

Crystallization, Mechanical, and Antimicrobial Properties of Diallyl Cyanuric Derivative-Grafted Polypropylene

“…As mentioned above, the free radicals, which originated from DCP decomposition at a high temperature, can initiate the grafting polymerization and lead to the chain breaking of PP simultaneously. − The most fundamental reason for the deterioration of mechanical properties of PP samples could be due to the degradation (molecular weight reduction) of PP. , The more the DTT addition, the more obvious the effect of molecular weight compensation on the recovery of mechanical properties of DTT-grafted PP samples.…”

“…As is known to all that in the free-radical grafting modification reaction, the excessive initiator will lead to a large number of degradation of polypropylene, increased melt flow rate, and decreased mechanical properties, resulting in difficulties in extrusion molding and practical use. 37 − 39 …”

“…Sun and Badrossamay studied the radical graft polymerization of several cyclic and acyclic N -halamines onto the backbone of PP during a reactive extrusion process and obtained very effective biocidal efficacy, with a six-log reduction of Gram-positive and Gram-negative bacteria within 30–60 min of contact time. ,, However, the effects of an N -halamine precursor on those properties related to the industrial proceeding of polymers on the performance of materials had rarely been investigated. As is known to all that in the free-radical grafting modification reaction, the excessive initiator will lead to a large number of degradation of polypropylene, increased melt flow rate, and decreased mechanical properties, resulting in difficulties in extrusion molding and practical use. − …”

A DFT mechanistic study on the N‐acyloxyamine‐initiated controlled degradation of polypropylene

“…However, the peroxides are highly energetic compounds that are prone to explosion and produce peroxide volatiles with high irritation odors in the controlled degradation process of PP. 25 The stable N-acyloxyamines were found to be potential radical initiators, which are safe and non-explosive peroxide alternatives for polymer-controlled degradation. [27][28][29] The design and screening of new and green radical initiators have been carried out based on the structure of N-acyloxyamine in the past decades.…”