Healable Network Polymers Bearing Flexible Poly(Lauryl Methacrylate) Chains via Thermo-Reversible Furan-Maleimide Diels–Alder Reaction Sachin S. Patil, Arun Torris A. T., Prakash P. Wadgaonkar Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India Correspondence to: P. P. Wadgaonkar (E-mail: pp.wadgaonkar@ncl.res.in) Received 26 March 2017; accepted 18 May 2017; published online 00 Month 2017 DOI: 10.1002/pola.28677 ABSTRACT: A new ATRP initiator containing two furyl rings, namely, bis(furan-2-ylmethyl) 2-bromopentanedioate was syn- thesized starting from commercially available L-glutamic acid as a precursor. Well-defined bisfuryl-terminated poly(lauryl methacrylate) macromonomers with molecular weight and dis- persity in the range 5000–12,000 g mol 21 and 1.30–1.37, respec- tively, were synthesized employing the initiator by atom transfer radical polymerization (ATRP). Independently, 1,1 0 ,1 00 - (nitrilotris(ethane-2,1-diyl))tris(1H-pyrrole-2,5-dione) was syn- thesized as a tris-maleimide counterpart for furan-maleimide click reaction. Thermo-reversible network polymer bearing flex- ible poly(lauryl methacrylate; (PLMA) chains was obtained by furan-maleimide Diels–Alder click reaction of bisfuryl- terminated PLMA with 1,1 0 ,1 00 -(nitrilotris(ethane-2,1-diyl))tris(1H- pyrrole-2,5-dione). The prepared network polymer showed retro-Diels–Alder reaction in the temperature range 110–170 8C as determined from DSC analysis. The presence of low Tg (–40 8C) PLMA chains induced chain mobility to the network struc- ture which led to the complete scratch healing of the coating at 60 8C in five days due to furan-maleimide adduct formation. The storage modulus of the network polymer was found to be 3.7 3 10 4 Pa at the constant angular frequency of 5 rad/sec and strain of 0.5%. The regular reversal of storage (G 0 ) and loss modulus (G 00 ) was observed with repeated heating (40 to 110 8C) and cooling cycles (110 to 40 8C) at constant angular fre- quency and strain. V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 00, 000–000 KEYWORDS: atom transfer radical polymerization; chain mobil- ity; Diels–Alder polymers; furan-maleimide click reaction; mac- romonomers; thermo-reversible network polymers INTRODUCTION Vulcanization and peroxide curing are the main industrial techniques for crosslinking of elastomers. The irreversible nature of these crosslinks prevents their reprocessability. 1 The cleavage of polymer backbone is one of the problems in thermal reprocessing of vulcanized and peroxide cured rubbers. 2 Considerable efforts have been devoted by scientific community for obtaining polymeric materials with reversible chemical bonding which can even- tually be easily processed and recycled. 3 Smart materials based on healable polymers 4,5 have contributed significantly to the field of coatings 6–8 and dielectrics. 9 The response of healable smart materials based on linear and crosslinked/ network polymers to temperature has been extensively stud- ied. 10–18 A range of smart materials based on supramolecular chemistry involving hydrogen bonding, k–k stacking, electrostatic-interactions, host–guest interactions, metal- coordiation and hydrophobic interactions have been stud- ied. 19–24 However, most of the supramolecular systems have been found to be mechanically weaker than the chemically crosslinked counterparts. For example, the storage modulus (G 0 ) of a supramolecular network polymer based on metal- coordination interactions between PNIPAAm with terpyridine side groups and Mn 12 ions has been reported to be lower than 1000 Pa at a frequency of 5 rad/sec. 25 Furthermore, a supramolecular system based on urea hydrogen bonding interactions exhibited the storage modulus of around 10 4 Pa at 5 rad/sec. 26 The combination of controlled polymerization methods such as NMP, ATRP, RAFT, and ROP with different click reactions such as thiol-ene, alkyne-azide, anthracene-maleimide, furan- maleimide, and aldehyde-aminooxy have been widely explored to obtain chemically crosslinked smart materi- als. 27,28 Of these, smart materials based on macromolecular architectures obtained by the combination of controlled radi- cal polymerization methods with furan-maleimide click reac- tion have been considered to be of practical interest due to their ease of accessability. 29–31 The thermo-reversible nature of furan-maleimide click reaction allows the material to heal Additional Supporting Information may be found in the online version of this article. V C 2017 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2017, 00, 000–000 1 JOURNAL OF POLYMER SCIENCE WWW.POLYMERCHEMISTRY.ORG ARTICLE