Synthesis and phase behavior of a polynorbornene‐based molecular brush with dual “jacketing” effects

Abstract

In this study, a series of well-defined liquid crystalline molecular brushes with dual "jacketing" effects, polynorbornene-g-poly{2,5-bis[(4-methoxyhenyl)oxycarbonyl] styrene} (PNb-g-PMPCS), were synthesized by the "grafting through" method from ring opening metathesis polymerization of anorbornenyl-terminated PMPCS. The rigid PMPCS side chain was synthesized by Cu(I)-catalyzed atom transfer radical polymerization initiated by N-[(2-bromo-2-methylpropanoyl)ethyl]-cis-5-norbornene-exo-2,3-dicarboximide. The chemical structures of the molecular brushes were confirmed by 1 H NMR and gel permeation chromatography (GPC), and the thermal properties were studied by thermogravimetric analysis (TGA). GPC results reveal that the molecular brushes have relatively narrow polydispersities. TGA results show that the molecular brushes have excellent thermal stabilities. The PMPCS side chains in all the molecular brushes form the columnar nematic liquid crystalline phase, which is a little different from the behavior of linear PMPCS possibly due to the confinement or other effects of the brush architecture which leads to decreased order.

Polymeric 19F MRI Contrast Agents Prepared by Ring-Opening Metathesis Polymerization/Dihydroxylation

“…Grubbs’ third generation catalyst ( G3 ) was synthesized from G2 by reaction with 5-bromopyridine (Fluorochem, 97%) at room-temperature (RT) and purified by filtration with dry pentane. N -(Hydroxyethyl)- cis -norbornene- exo -2,3-dicarboxiimide ( S2 ) and exo- N -methyl-norbornene-2,3-dicarboxiimide ( M0 ) were prepared, as reported previously. Flash chromatography was performed on silica gel (SiliCycle, 230–400 mesh, particle size 32–63 μm, 60 Å).…”

“…24 Perfluoro-tert-butoxyethyl-cis-norbornene-exo-2,3-dicarboxiimide (M2). N-(Hydroxyethyl)-cis-norbornene-exo-2,3-dicarboxiimide (S2, 486 mg, 2.35 mmol) synthesized according to a previous procedure 26 and triphenylphosphine (738 mg, 2.81 mmol) were dissolved in dry tetrahydrofuran (THF) (10 mL). Next, DIAD (446 μL, 2.81 mmol) predissolved in 8 mL of THF was added dropwise to the reaction mixture over 5 min.…”

Solid Polymer Electrolytes with Excellent High-Temperature Properties Based on Brush Block Copolymers Having Rigid Side Chains

“…The Nb-PEO macromonomer was synthesized according to the literature, and the detailed process is described in the Supporting Information (Scheme S1). The Nb-PMPCS macromonomers were synthesized according to our previous work . The BBCPs were synthesized with tandem ROMP.…”

“…The Nb-PMPCS macromonomers were synthesized according to our previous work. 37 The BBCPs were synthesized with tandem ROMP. The synthesis of gPEO 24 -b-gPMPCS 23 (the numbers represent the DPs of the side chains) is a Determined by GPC in THF (calibrated with PS standards).…”

Orthogonal synthesis and modification of polymer materials

“…Although this example was not carried out in a single pot, and still required handling and purification steps to form the desired bottlebrush polymer, the utility of this orthogonal chemistry for producing sequence defined macromolecules cannot be understated. Furthermore, though RAFT and ATRP are truly orthogonal polymerizations in this synthesis, ROMP, with a few exceptions, 156,157 typically must be performed first to avoid cross‐reactivity of the norbornene type monomers with RDRP methodologies calling into question the orthogonal nature of this polymerization. As the most useful approaches for sequence‐defined macromolecular synthesis involve iterative growth, orthogonal chemistry is required to ensure that highly selective coupling of the desired functionalities occurs (Figure 12).…”