Ethylene/hindered phenol substituted norbornene copolymers: Synthesis and NMR structural determination

Abstract

A new family of ethylene-based copolymers with controlled amounts of a norbornene comonomer (N ArOH ) bearing a stabilizing antioxidant functionality (2,6-di-tert-butyl phenol) was prepared. Due to unavoidable exo/endo equilibrium operative in N ArOH comonomer, a complete and detailed NMR assignment of the structure of the prepared ethylene/N ArOH copolymers was carried out for the determination of the exo/ endo ratio inside the polymer. These novel functionalized comonomers can be considered suitable starting material for preparing ethylene-based copolymers, with tunable comonomer content, as non-releasing macromolecular antioxidant additives for specific application in safe food and/or drug packaging V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: [4647][4648][4649][4650][4651][4652][4653][4654][4655] 2012 Additional Supporting Information may be found in the online version of this article.

Synthesis and Properties of Polyethylene‐Bound Antioxidants

“…Many approaches have been developed to retard the physical loss of antioxidants, such as producing antioxidants with high MW, immobilizing antioxidants onto nanoparticles, and chemically attaching antioxidants to polymers. Polymer‐bound antioxidants can be prepared by (co)polymerizations of monomers bearing stabilizing functionalities and polymer functionalization of: i) pre‐functionalized polymer bearing reactive groups with low‐MW compounds bearing stabilizing moieties and ii) conventional polymers with monomers bearing stabilizing moieties . Studies already show that the ideal stabilizer should be highly soluble, minimally diffusive, and homogeneously distributed in the polymer matrix .…”

Design and Synthesis of Olefin Copolymers with Tunable Amounts of Comonomers Bearing Stabilizing Functionalities

“…Moreover, a norbornene comonomer could be quite interesting for the preparation of non‐releasing additives specifically destined to protect commercial E/N copolymers, a package material particularly used for pharmaceuticals, with high added value and health impact. A route was designed to obtain the pure exo ‐isomer (exo‐ 4 ),6 known to be more reactive than the endo ‐isomer in polymerization 7. However, we verified that exo ‐ 4 was not stereostable on standing, since variable amounts of the endo ‐isomer were formed, due to a retro‐Diels‐Alder/Diels‐Alder process.…”

“…The synthetic route and the effect of the exo / endo ratio of the comonomer on the copolymerization are described in ref. 6…”

“…Triisobutylaluminum (TIBA) was used for protecting the functional units to prevent the catalyst deactivation. By varying the E/comonomer molar ratio in the feed, it was possible the tuning of the functionalized comonomer content up to 5 mol% 4, 6…”

Synthesis of Polyethylene‐Grafted Phosphite Antioxidant and Its Antioxidant Behavior in Polypropylene

“…Synthesis and application research of the phosphorus‐containing antioxidants has drawn the attention of many prominent researchers. [ 1,7–10 ] For example, Meng et al had synthesized one kind of phosphite antioxidant named bis‐2,2'‐methyl‐4,6‐di‐tert‐butylphenyl phosphite and this antioxidant contained a water‐resistant inner ring and a free phenolic hydroxyl group. [ 10 ] Due to the intermolecular synergistic effect, this antioxidant displayed good antioxidation.…”