Effect of Biphenyl Spacers on the Anionic Polymerization of 2‑(4′-Vinylbiphenyl-4-yl)pyridine

The pyridine-containing monomer 2-(4′-vinylbiphenyl-4-yl)­pyridine (VBPPy), synthesized by the Suzuki coupling reaction, was successfully polymerized using diphenylmethylpotassium (DPM-K) as an initiator within 360 min at −78 °C, resulting in 100% yield and polydispersity <1.3, as with the living anionic polymerization of 2-vinylpyridine (2VP) and 2-(4-vinylphenyl)­pyridine (VPPy). By the block copolymerization of VBPPy with 2VP, VPPy, and methyl methacrylate (MMA), it was proven that the nucleophilicity of living poly­(2-(4′-vinylbiphenyl-4-yl)­pyridine) is between that of living poly­(2-(4-vinylphenyl)­pyridine) and that of living poly­(methyl methacrylate). Among the block copolymers, PVBPPy-b-PMMA was used to make nanocomposites in which gold (Au) nanoparticles (NPs) were present only in the PVBPPy zone of the phase-separated PVBPPy-b-PMMA) (fVBPPy = 0.23) film

Formation of Intermicellar-Chained and Cylindrical Micellar Networks From an Amphiphilic Rod−Coil Block Copolymer: Poly(<i>n</i>-hexyl isocyanate)-<i>block</i>-poly(2-vinylpyridine)

Morphologies of the poly(n-hexyl isocyanate)-block-poly(2-vinylpyridine) (PHIC-b-P2VP, fP2VP = 0.3) amphiphilic rod−coil block copolymer were studied in rod-selective chloroform (CHCl3), both-block-soluble tetrahydrofuran (THF), and CHCl3/THF mixed solvent systems. Spherical, solid micelles with a P2VP core and PHIC shell were formed in CHCl3, whereas a microphase-separated liquid crystalline morphology was prominent in the presence of THF. In the CHCl3/THF mixed solvent system, a unique long-range intermicellar-chained network (v/v = 7/3) and a more evolved cylindrical micellar network (v/v = 3/7) were remarkably formed, respectively. PHIC-b-P2VP network nanostructures were used as a template for the in situ synthesis of Au nanoparticles (8 nm) selectively within the functional P2VP core domains

Effects of Different Reactive Oxyanionic Initiators on the Anionic Polymerizaition of <i>n</i>-Hexyl Isocyanate

Poly(n-hexyl isocyanate) was synthesized by anionic polymerization using various oxy-initiators, including sodium phenoxide (Na-PO), sodium benzhydroxide (Na-BH), and sodium methoxyphenylethoxide (Na-MPE). We optimized polymerization conditions. To confirm the living natures of the polymerization, we carried out various polymerizations changing mole ratio between monomers and initiators and a postpolymerization by sequential monomer addition method. Our results indicated that the anionic polymerization of n-hexyl isocyanate was not controlled using Na-PO and Na-MPE. However, Na-BH as an initiator is favorable for the living anionic polymerization of n-hexyl isocyanate because it has a dual function in the initiation and in the efficient prevetion of trimerization by reducing the reactivity at the growth chain ends. Polymers were thus synthesized with predictable molecular weights (MW), narrow molecular weight distributions (MWD), and high yields

Liquid Crystalline Ordering in the Self-Assembled Monolayers of Tethered Rodlike Polymers

We show that tethering rodlike polymers onto solid surfaces by their chain ends with a moderate grafting density can lead to highly oriented anisotropic self-assembled monolayers (SAM) with thickness identical to the diameter of single chain through liquid crystalline ordering. The polymers employed for this study were di- or triblock copolymers composed of poly(n-hexylisocyanate)(PHIC), a rodlike polymer, and poly(2-vinylpyridine)(P2VP), a surface-reactive coil. The block copolymers formed SAM of PHICs tethered to the surface through adsorption of P2VP onto mica. Planar nematic ordering occurred to the PHIC chains when the monolayer was exposed to the vapor of selective solvents. Anisotropic SAMs with long-range order were obtained by exposing the monolayer to THF vapor, which was accounted for by reorganization of PHIC chains with change of anchoring points through partial sorption/desorption of P2VP segments by THF vapor

Self-Organization of an Amphiphilic Rod−Coil−Rod Block Copolymer into Liquid Crystalline, Substrate-Supported Monolayers and Bilayers

We report that the amphiphilic rod−coil−rod triblock copolymer with a coil attractive to the substrate surface self-organize into liquid crystalline monolayers or bilayers of a few nanometers thickness on the substrate surface. The copolymer investigated is a triblock copolymer, poly(n-hexyl isocyanate-b-2-vinylpyridine-b-n-hexyl isocyanate) (PHIC-b-P2VP-b-PHIC). Key processes of self-organization in the thin films, such as adsorption, desorption, diffusion, nematic and smectic ordering, and microphase separation, are tuned by exposing dip- or immersion-coated nanoscale films to the vapor of solvents which are rod (PHIC)-selective, coil (P2VP)-selective, or good to both blocks. Reorganization of the rod−coils in the nanofilms yielded various morphologies in the monolayer or bilayer, including unique long-range-ordered, smectic-on-nematic biphasic sheets. The results offer understanding on the complex morphological evolution in amphiphilic rod−coil block copolymers on the substrate surface

Fluorinated Poly(arylene ether sulfide) for Polymeric Optical Waveguide Devices

Fluorinated poly(arylene ether sulfide)s containing an ethynyl group (E-FPAESI) were synthesized by nucleophilic aromatic substitution from 4,4‘-(hexafluoroisopropylidene)diphenol (6FBPA) and an excess of pentafluorophenyl sulfide, followed by reaction with 3-ethynylphenol. The molecular weights (Mn's) and polydispersities (Mw/Mn's) of the E-FPAESI determined by GPC with polystyrene standard were in the range 14 200−25 200 and 2.23−2.47, respectively. The polymer films were fabricated by spin-coating and cross-linked by thermal curing. The cured films had good chemical resistance for common solvents such as acetone, tetrahydrofuran (THF), methylene chloride, chloroform, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). The glass transition temperature of E-FPAESI was changed from 120 to 160 °C after curing and showed high thermal stability up to 489 °C. At 1.55 μm wavelength, the refractive indices and birefringences of the films were in the range 1.5200−1.5515 and 0.0034−0.0044, respectively, depending on feed ratio of 6FBPA and 4,4‘-(trifluoromethylphenylisopropylidene)diphenol (3FBPA). The optical loss for E-FPAESI was measured to be less than 0.40 dB/cm

Au-Coated 3-D Nanoporous Titania Layer Prepared Using Polystyrene-<i>b</i>-poly(2-vinylpyridine) Block Copolymer Nanoparticles

New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core−shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 °C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching