Graft Copolymers via ROMP and Diels–Alder Click Reaction Strategy HAKAN DURMAZ, AYDAN DAG, NESE CERIT, OKAN SIRKECIOGLU, GURKAN HIZAL, UMIT TUNCA Department of Chemistry, Istanbul Technical University, Maslak, Istanbul 34469, Turkey Received 22 September 2010; accepted 23 September 2010 DOI: 10.1002/pola.24418 Published online 8 November 2010 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Anthracene-functionalized oxanorbornene monomer and oxanorbornenyl polystyrene (PS) with x-anthracene end- functionalized macromonomer were first polymerized via ring- opening metathesis polymerization using the first-generation Grubbs’ catalyst in dichloromethane at room temperature and then clicked with maleimide end-functionalized polymers, poly(ethylene glycol) (PEG)-MI, poly(methyl methacrylate) (PMMA)-MI, and poly(tert-butylacrylate)(PtBA)-MI in a Diels– Alder reaction in toluene at 120 C to create corresponding graft copolymers, poly(oxanorbornene)-g-PEG, poly(oxanorbor- nene)-g-PMMA, and graft block copolymers, poly(oxanorbor- nene)-g-(PS-b-PEG),poly(oxanorbornene)-g-(PS-b-PMMA),and poly(oxanorbornene)-g-(PS-b-PtBA),respectively. Diels–Alder click reaction efficiency for graft copolymerization was moni- tored by UV–vis spectroscopy. The dn/dc values of graft copolymers and graft block copolymers were experimentally obtained using a triple detection gelpermeation chromatogra- phy and subsequently introduced to the software so as to give molecular weights, intrinsic viscosity ([g]) and hydrodynamic radius (R h ) values. V C 2010 Wiley Periodicals,Inc. J Polym Sci Part A: Polym Chem 48: 5982–5991, 2010 KEYWORDS: anthracene; Diels–Alder click reaction; graft copoly- mer; graft block copolymer; Grubbs’ first-generation catalyst; oxanorbornene;ring-opening metathesis polymerization; triple detection GPC; UV–vis spectroscopy INTRODUCTION A combinationof living polymerization methods and their compatible partner click reactions allows increasingly the synthesis of the complex macromolecular structures, such as star, cyclic,hyperbranched polymers, den- drimers,and graftcopolymers, with well-defined molecular weight,composition, topology, and functional groups. 1–13 It is well known thatcomplex architectures display different propertiesboth in bulk and solution,that is, morphology and assembly in solution and in bulk, and the solution and the melt viscosity,when compared with their linear counterparts. Graft copolymers can be obtained with three general meth- ods: (i) grafting-onto, in which side chains are preformed, and then attached to the main polymer backbone; (ii) graft- ing-from,in which the monomer is grafted from the main backbone;and (iii) grafting-through, in which the macro- monomersare copolymerized to givethe resultantgraft copolymer. 14,15 Among living polymerization methods, ring-opening metathe- sis polymerization (ROMP) is a versatile and an efficient syn- thetic strategy for the polymerization of cyclic olefins (such as norbornenenorbornadieneand dicyclopentadiene) by using metal alkylideneinitiators (e.g.,molybdenum and ruthenium complex catalysis). 16–34 Although there have been many published studies on the synthesis of graft copolymers by using a combination of ROMP and other living polymer- ization techniques 35 ; such as ROMP–ROMP, 36–39 ROMP–atom transferradicalpolymerization, 40–44 ROMP–reversible addi- tion fragmentation chain transfer polymerization, 45–47 ROMP– living anionic polymerization, 48,49 and ROMP–ring-opening polymerization combinations, 50–52 relatively few publications have emerged in the literature based on combining ROMP and click reactions. Grubbs first time used a ROMP–click combina- tion for the synthesisof graft copolymersusing grafting- through method. 53 Various macromonomers were efficiently synthesized through azide-alkyne click reaction of a norbor- nene-alkyne with azido terminal group of polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(tert-butyl acry- late) (PtBA).ROMP of these macromonomers were carried out using the ruthenium catalyst, (H 2 IMes)(pyr) 2 (Cl) 2 RuCHPh in tetrahydrofuran (THF) at room temperature to give graft copolymerswith narrow polydispersity and high molecular weights. Later,Fontaine et al. used same strategy by reacting alkyne-functionalized oxanorbornenewithazido-terminated poly(ethylene glycol) (PEG) so as to give x-oxanorbornenyl PEG macromonomers. 54 Subsequent ROMP of these macro- monomersgave poly(oxanorbornene)-g-PEG with narrow polydispersity and moderate molecular weights using third- generation Grubbs’ catalyst in dichloromethane at room tem- perature via grafting-through method. Recently,our group has reported the synthesisof well- defined graft copolymers 55 and heterograft copolymers 56 via Additional Supporting Information may be found in the online version of this article. Correspondence to: U. Tunca (E-mail: tuncau@itu.edu.tr) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 48, 5982–5991 (2010) V C 2010 Wiley Periodicals, Inc. 5982 WILEYONLINELIBRARY.COM/JOURNAL/JPOLA