Polymerization of n-Hexyl Isocyanate with CpTiCl 2 (OR) (R = Functional Group or Macromolecular Chain): A Route to x-Functionalized and Block Copolymers and Terpolymers of n-Hexyl Isocyanate STYLIANOS MOURMOURIS, KONSTANTINOS KOSTAKIS, MARINOS PITSIKALIS, NIKOS HADJICHRISTIDIS Industrial Chemistry Laboratory, Department of Chemistry, University of Athens, 15771 Panepistimiopolis Zografou, Athens, Greece Received 17 August 2005; accepted 13 September 2005 DOI: 10.1002/pola.21129 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Well-defined x-cholesteryl poly(n-hexyl isocyanate) (PHIC–Chol), as well as diblock copolymers of n-hexyl isocyanate (HIC) with styrene, PS-b-PHIC [PS ¼ poly- styrene; PHIC ¼ poly(n-hexyl isocyanate)], and triblock terpolymers with styrene and isoprene, PS-b-PI-b-PHIC and PI-b-PS-b-PHIC (PI ¼ polyisoprene), were synthesized with CpTiCl 2 (OR) (R ¼ cholesteryl group, PS, or PS-b-PI) complexes. The synthetic strategy involved the reaction of the precursor complex CpTiCl 3 with cholesterol or the suitable x-hydroxy homopolymer or block copolymer, followed by the polymerization of HIC. The x-hydroxy polymers were prepared by the anionic polymerization of the cor- responding monomers and the reaction of the living chains with ethylene oxide. The reaction sequence was monitored by size exclusion chromatography, and the final prod- ucts were characterized by size exclusion chromatography (light scattering and refrac- tive-index detectors), nuclear magnetic resonance spectroscopy, and, in the case of PHIC–Chol, differential scanning calorimetry. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6503–6514, 2005 Keywords: anionic polymerization; catalytic polymerization; copolymers; differen- tial scanning calorimetry (DSC); n-hexyl isocyanate; NMR; size exclusion chromatog- raphy (SEC); terpolymers INTRODUCTION Polyisocyanates (PICs) are an unusual class of polymeric materials that adopt helical conforma- tions both in solution and in bulk. 1 Numerous characterization techniques have shown that PICs are stiff-chain polymers whose properties depend on several parameters, such as the na- ture of the isocyanate side group, temperature, solvent, and molecular weight. 2 Consequently, they may behave either as rigid rods or as semi- flexible, wormlike chains. A combination of PICs with flexible chains in diblock copolymers or more complex macromolecular architectures pro- vides new challenges in nanotechnology regard- ing the microphase separation, the ordering kinetics, and the self-assembly behavior in solu- tion. 3 Therefore, novel high-tech applications are expected to emerge, making these materials possible candidates as optical switches, recogni- tion devices, and so forth. 4 The limiting factor in the development of all these possible applications of PICs is the lack of Correspondence to: N. Hadjichristidis (E-mail: hadjichristidis@ chem.uoa.gr) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 43, 6503–6514 (2005) V V C 2005 Wiley Periodicals, Inc. 6503