Synthesis and characterization of chiral poly(l‐lactide‐b‐hexyl isocyanate) macromonomers with norbornenyl end groups and their homopolymerization through ring opening metathesis polymerization to afford polymer brushes

ABSTRACT We report the synthesis of the novel half‐titanocene alkoxide complex bischloro‐η5‐cyclopentadienyl(bicyclo[2.2.1]‐hept‐5‐en‐2‐oxy) titanium (IV), [CpTiCl2(O‐NBE)]. This complex was employed for the synthesis of chiral poly(l‐lactide‐b‐hexyl isocyanate) diblock copolymer bearing a norbornene end group with sequential addition of monomers. The poly(hexyl isocyanate) block is chiral due to the last l‐lactide unit of the poly(l‐lactide) block. This macromonomer was polymerized towards a chiral polymer brush structure with polynorbornene backbone and chiral poly(l‐lactide‐b‐hexyl isocyanate) side chains using Grubbs first‐generation catalyst. The polymers were characterized using size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), and circular dichroism (CD) spectroscopy and their thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1102–1112 In this work, the synthesis, characterization, optical and thermal properties of polynorbornene polymer brushes bearing chiral poly(l‐lactide‐b‐hexyl isocyanate) side chains is investigated. The main feature of the diblock copolymer is the chirality of the poly(hexyl isocyanate) block, which is induced by the poly(l‐lactide) block. The chirality is totally maintained in each side chain of the brush copolymer.