Polymerization of n‐hexyl isocyanate with CpTiCl₂(OR) (R = functional group or macromolecular chain): A route to ω‐functionalized and block copolymers and terpolymers of n‐hexyl isocyanate

Abstract

Well‐defined ω‐cholesteryl poly(n‐hexyl isocyanate) (PHIC–Chol), as well as diblock copolymers of n‐hexyl isocyanate (HIC) with styrene, PS‐b‐PHIC [PS = polystyrene; PHIC = poly(n‐hexyl isocyanate)], and triblock terpolymers with styrene and isoprene, PS‐b‐PI‐b‐PHIC and PI‐b‐PS‐b‐PHIC (PI = polyisoprene), were synthesized with CpTiCl2(OR) (R = cholesteryl group, PS, or PS‐b‐PI) complexes. The synthetic strategy involved the reaction of the precursor complex CpTiCl3 with cholesterol or the suitable ω‐hydroxy homopolymer or block copolymer, followed by the polymerization of HIC. The ω‐hydroxy polymers were prepared by the anionic polymerization of the corresponding monomers and the reaction of the living chains with ethylene oxide. The reaction sequence was monitored by size exclusion chromatography, and the final products were characterized by size exclusion chromatography (light scattering and refractive‐index detectors), nuclear magnetic resonance spectroscopy, and, in the case of PHIC–Chol, differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6503–6514, 2005

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

“…Another important advantage of the coordination polymerization using half‐titanocene alkoxides is the capability of incorporating the complex on OH groups of a polymer chain. Subsequent polymerization of hexyl isocyanate or lactides leads to block copolymers and very interesting macromolecular architectures …”

Micellization Behaviour of Linear and Nonlinear Block Copolymers Based on Poly(n-hexyl isocyanate) in Selective Solvents

“…The polymer synthesis was accomplished through anionic and coordination polymerization techniques as previously described in the literature [44][45][46][47][48][49][50].…”

“…The diblock copolymers having polystyrene (PS) and PHIC blocks were synthesized either by anionic (SH121/90/10 and SH187/92/8) or by coordination polymerization techniques (SH14/3/97, SH7.5/9/91, SH19.5/11/89 and SH14/18/82) [44][45][46][47][48][49][50]. The samples are symbolized as SH followed by numbers denoting the sample's molecular weight (in KDa), the % wt content is PS and the % wt content in PHIC.…”

“…Thus, polyisocyanates possess an extended 8/3 helical conformation instead of a restricted coplanar conformation [43]. Block copolymers with polystyrene (PS) and polyisoprene (PI) [44][45][46], triblock copolymers, pentablock terpolymers [47], graft copolymers, star polymers, star-block copolymers, miktoarm stars and block-graft copolymers [48][49][50] have been synthesized based either on anionic [51] or coordination polymerization of n-hexyl isocyanate, HIC employing half-Titanocene complexes [52][53][54][55][56][57]. Polyisocyanates have found tremendous applications in nanoscience and materials science as degradable and chiral recognition materials, optical switches, liquid crystals, etc.…”

Room temperature polymerization of alkyl isocyanates catalyzed by rare earth Schiff base complexes

“…Some coordination polymerizations make a living polymerization of isocyanates possible, and the polymer yield varies from 74% to 95% after 24 h polymerization [10][11][12][13] . Hadjichristidis et al synthesized functionalized homo and block copolymers of n-HexNCO and complex macromolecular architectures based on nHexNCO using functionalized anionic initiators or organotitanium catalysts, and organotitanium macroinitiator [14][15][16] . Furthermore, rare earth catalysts, especially rare earth organometallic compounds, are also used for the polymerization of isocyanates.…”