Synthesis and Characterization of Brush Diblock and Triblock Copolymers Bearing Polynorbornene Backbone and Poly(L-lactide) and/or Poly(hexyl isocyanate) Side Chains by a Combination of Coordination and Ring Opening Metathesis Polymerization Ioannis Choinopoulos , 1,2 George Patias, 1 Spyros Koinis, 2 Marinos Pitsikalis 1 1 Department of Chemistry, Industrial Chemistry Laboratory, National and Kapodistrian University of Athens, 15771 Panepistimiopolis Zografou, Athens, Greece 2 Department of Chemistry, Laboratory of Inorganic Chemistry, National and Kapodistrian University of Athens, 15771 Panepistimiopolis Zografou, Athens, Greece Correspondence to: I. Choinopoulos (E-mail: ichoinop@chem.uoa.gr) or M. Pitsikalis pitsikalis@chem.uoa.gr Received 21 June 2017; accepted 7 July 2017; published online 00 Month 2017 DOI: 10.1002/pola.28727 ABSTRACT: We report the synthesis of poly(L-lactide) and poly- (hexyl isocyanate) macromonomers using bischloro-g 5 -cyclo- pentadienyl(bicyclo[2.2.1]-hept-5-en-2-oxy) Titanium (IV), [CpTi- Cl 2 (O-NBE)]. These macromonomers bearing a norbornene end group were polymerized towards brush copolymers employing Grubbs’ first generation catalyst. Brush copolymers consisting of blocks with different side chains were synthesized. The poly- mers were characterized by Size Exclusion Chromatography, Nuclear Magnetic Resonance, and their thermal properties were investigated by Thermogravimetric Analysis, and Differ- ential Scanning Calorimetry analysis. V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 00, 000–000 KEYWORDS: hexyl isocyanate; lactide; macromonomers; metal- locenes; polymer brush; ROMP INTRODUCTION Densely grafted copolymers or polymer brushes are advanced macromolecular architectures. They consist of a backbone, which bears a side polymeric chain for each monomeric unit. Infinite combinations of main and side chains are theoretically possible, but synthetic difficul- ties limit these options. In contrast with grafting onto or grafting from, grafting through is the only method that leads to structures where each monomeric unit bears a side chain without any doubt. This method requires the use of suitable techniques for the polymerization of polymeric chains bear- ing a polymerizable unit (macromonomers). 1 Polylactides have been studied quite extensively due to their interesting properties, which are exploited in many applica- tions (packaging, medicine, surgery, pharmaceutical prod- ucts). Their origin from biomass, their biocompatibility, and biodegradability constitute their main ecological and eco- nomic advantages. Polylactide macromonomers bearing nor- bornene polymerizable end groups have been prepared using several methods by other groups. The synthesis, char- acterization and properties of polymer brushes with polynor- bornene main chain and polylactide side chains has been reported in the literature. 2–6 Novak and coworkers have also reported the synthesis of poly(hexyl isocyanate) macromono- mers, using a half-titanocene alkoxide complex, but no rele- vant data have been published. 7 To our knowledge, only Grubbs and coworkers have reported the synthesis of poly(hexyl isocyanate) macromonomers bearing norbornene end groups and their incorporation in brush copolymer synthesis. 8 Ring Opening Metathesis Polymerization (ROMP) of the mac- romonomer norbornene end groups is conducted mainly by Grubbs’ catalysts. Third generation Grubbs’ catalysts are gen- erally preferred because of their tolerance towards func- tional groups and the increased polymerization rate compared with first and second generation catalysts. In addi- tion, there is control of the polymerization reaction, leading to low dispersities and the capability of block formation. 3 Although Grubbs’ first generation catalyst has slow reaction rate, our previous experience proved its efficiency and very well controlled ROMP reactions were performed with macro- monomers similar to those employed in this work. 9 Further- more, the catalyst was not poisoned by the functional groups 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