Synthesis of Amphiphilic Helix–Coil–Helix Poly(3-(glycerylthio)propyl isocyanate)-<i>block</i>-polystyrene-<i>block</i>-poly(3-(glycerylthio)propyl isocyanate)

To achieve molecular packing of protic-functionalized helical polymers in aqueous solution, we synthesized an amphiphilic helix–coil–helix triblock copolymer (triBCP) composed of polystyrene and dihydroxyl-functionalized polyisocyanates. Poly­(3-(glycerylthio)­propyl isocyanate)-<i>block</i>-polystyrene-<i>block</i>-poly­(3-(glycerylthio)­propyl isocyanate), P3GPIC-<i>b</i>-PSt-<i>b</i>-P3GPIC, was synthesized by postpolymerization modification. The bidirectional anionic block copolymerization of styrene (St) and allyl isocyanate (AIC) yielded triBCPs, poly­(allyl isocyanate)-<i>block</i>-polystyrene-<i>block</i>-poly­(allyl isocyanate)­s (PAIC-<i>b</i>-PSt-<i>b</i>-PAICs), with well-controlled molecular weights (<i>M</i>_n = 5.60–99.9 kDa) and narrow dispersities (<i>Đ</i> = 1.14–1.18). Of them, one with the lowest MW (<i>M</i>_n = 5.60 kDa, <i>Đ</i> = 1.14), which was highly organic-soluble, was utilized in the thiol–ene click reaction between allyl group and 1-thioglycerol, producing P3GPIC-<i>b</i>-PSt-<i>b</i>-P3GPIC. The amphiphilic P3GPIC-<i>b</i>-PSt-<i>b</i>-P3GPIC self-aggregated to form spherical vesicles with an average hydrodynamic diameter of 170 nm in aqueous solution, demonstrating that hydrophilic–helical P3GPIC blocks well interacted with water media maintaining their intermolecular packing

Fluorinated Aromatic Polyether Ionomers Containing Perfluorocyclobutyl as Cross-Link Groups for Fuel Cell Applications

The cross-linkable copolymers (SHQ<i>x</i>-TFV<i>y</i>s) with varying degrees of sulfonation (DS) from 70 to 95% were prepared from potassium-2,5-dihydroxybenzenesulfonate (SHQ), decafluorobiphenyl (DFBP), and 4-(trifluorovinyloxy)-biphenyl-2,5-diol (TFVOH) as a cross-linkable moiety. To develop a highly stable polymer electrolyte membrane (PEM) for application in polymer electrolyte fuel cells (PEFC)­s, cross-linked membranes were prepared by chemical cross-linking. The cross-linked membranes were synthesized by varying the amount of TFVOH (5–30 mol %) in order to achieve desirable PEM properties. The structures of the cross-linkable monomer and polymers were investigated by ¹H and ¹⁹F NMR and FT-IR spectra. The cross-linked membranes exhibited good glass transition temperature and thermal stability up to 239–271 °C and 290–312 °C, respectively. The crosslinked membranes (DS range 80–95%) exhibited higher proton conductivity (0.098–0.151 S/cm) than Nafion 212 (0.092 S/cm). Moreover, all membranes possessed lower methanol permeability (13–132 × 10^–8 cm²/s) compared with Nafion 212 (163 × 10^–8 cm²/s) under the same measurement conditions. The H₂/O₂ single cell performance tests of the cross-linked membranes and Nafion 212 were performed. The CSHQ90-TFV10 exhibited the higher maximum power density (1.053 W/cm²) than that of Nafion 212 (0.844 W/cm²)

Morphological Control over ZnO Nanostructures from Self-Emulsion Polymerization

Three different morphologies of ZnO nanostructures, such as nanospheres, nanorods, and nanoribbons, were controlled by tuning the ratio of the Zn²⁺ precursor to the 4VP monomer when polymerized in aqueous medium utilizing self-emulsion polymerization. The amphiphilic homopolymer (P4VP) acts as a template to form the ZnO/P4VP nanocomposite. The aspect ratio of the nanostructures is strongly dependent on the molar concentration of the Zn²⁺ precursor and becomes higher as its concentration increases. This results in different morphologies that are consistently repeatable. Pure ZnO was obtained from the ZnO/P4VP nanocomposites by calcination at 400 °C or by solvent washing. The calcination of the nanocomposties resulted in different morphologies, such as spherical, corolla shaped, and nanosheets. In addition, hexagonal nanoblocks, nanorods, and nanoribbons were observed when the polymer was removed from the nanocomposites by washing with chloroform. Removing polymer by solvent washing is a very easy, cost-effective method and has the potential for mass production of pure and highly crystalline ZnO nanostructures with known and controllable morphologies. The nanocomposites and pure ZnO nanostructures obtained after polymer removal were characterized by transmission electron microscopy, high resolution transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses, which confirmed the crystalline nature of the ZnO

Synthesis of Novel Amphiphilic Polyisocyanate Block Copolymer with Hydroxyl Side Group

A novel amphiphilic polyisocyanate block copolymer with hydroxyl side groups was synthesized by a combination of living anionic polymerization and thiol–ene click chemistry. First, the living anionic block copolymerization of allyl isocyanate (AIC) and <i>n</i>-hexyl isocyanate (HIC) produced a well-defined block copolymer (PAIC-<i>b</i>-PHIC) as a precursor. The subsequent free-radical-mediated thiol–ene click reaction of this polymer with 2-mercaptoethanol at room temperature quantitatively converted the allyl side groups of the PAIC domain to hydroxyl groups, finally creating PAIC­(OH)-<i>b</i>-PHIC. The amphiphilicity of PAIC­(OH)-<i>b</i>-PHIC led to lamellar and cylindrical phase separations in the thin films cast from different solvents (THF and toluene). The functionalities and phase separation behaviors of PAIC­(OH)-<i>b</i>-PHIC were characterized by NMR, SEC-MALLS, and TEM analysis

Well-Defined Block Copolymers with Triphenylamine and Isocyanate Moieties Synthesized via Living Anionic Polymerization for Polymer-Based Resistive Memory Applications: Effect of Morphological Structures on Nonvolatile Memory Performances

The anionic block copolymerization of 4,4′-vinylphenyl-<i>N</i>,<i>N</i>-bis­(4-<i>tert</i>-butylphenyl)­benzenamine (<b>A</b>) with <i>n</i>-hexyl isocyanate (<b>B</b>) was performed using potassium naphthalenide (K-Naph) in THF at −78 and −98 °C in the presence of sodium tetraphenylborate (NaBPh₄) to afford the well-defined block copolymers for investigating the effect of morphological structures on electrical memory performances. The well-defined functional block copolymers (P<b>BAB</b>) with different block ratios had predictable molecular weights (<i>M</i>_n = 17 700–79 100 g/mol) and narrow molecular weight distributions (<i>M</i>_w/<i>M</i>_n = 1.14–1.19). It was observed from transmission electron microscopy (TEM) that the block copolymers showed different morphological structures depending on block ratios. Although all memory devices fabricated from the resulting block copolymers with different block compositions equally exhibited nonvolatile resistive switching characteristics, which are governed by the trap-controlled space-charge-limited current (SCLC) conduction mechanism and filament formation, it was found that electrical memory performances of each device varied depending on morphological structures of the block copolymer films

Exploration of the Mechanism for Self-Emulsion Polymerization of Amphiphilic Vinylpyridine

A rare self-assembly behavior is observed in a hydrophilic monomer (4-vinylpyridine) (4VP) when polymerized in water with a hydrophilic initiator that results in the production of monodisperse polymeric nanoparticles in a single step. This behavior mimics the behavior obtained with the more commonly reported amphiphilic block copolymers. The synthesis and self-assembly of homopolymer nanoparticle from 4VP without the use of any cross-linker, stabilizing agent, surfactant, or polymeric emulsifier are described along with fundamental aspects of the mechanism of this polymerization. This facile and robust procedure enabled the production of highly monodisperse P4VP nanoparticle with a tunable size ranging from 80 to 445 nm. For the first time, we have investigated the growth mechanism of these polymeric nanoparticles to clarify the mechanism of polymeric nanoparticle formation. This work also provides direct visible evidence through transmission electron microscopy (TEM) images at the nanometer scale, which helps in obtaining a better understanding of the mechanism of self-assembly. The effect of temperature on the size of the polymeric nanoparticles was also examined along with the effect of initiator, monomer, and solvent concentrations. We therefore report a versatile and scalable process for the production of monodisperse polymeric nanoparticles, which we call self-emulsion polymerization (SEP)

Living Anionic Polymerization of <i>N</i>‑(1-Adamantyl)‑<i>N</i>‑4-vinyl­benzylidene­amine and <i>N</i>‑(2-Adamantyl)‑<i>N</i>‑4-vinyl­benzylidene­amine: Effects of Adamantyl Groups on Polymerization Behaviors and Thermal Properties

The anionic polymerization of <i>N</i>-(1-adamantyl)-<i>N</i>-4-vinylbenzylidene­amine (<b>1</b>) and <i>N</i>-(2-adamantyl)-<i>N</i>-4-vinylbenzylidene­amine (<b>2</b>) was performed using various initiators, such as oligo­(α-methylstyryl)­dipotassium, potassium naphthalenide, diphenyl­methylpotassium, and diphenyl­methyllithium, in THF at −78 °C for 1 h to investigate the effects of adamantyl groups on the polymerization behaviors and thermal properties of the resulting polymers. The well-defined poly­(<b>1</b>) and poly­(<b>2</b>) with predictable molecular weights and narrow molecular weight distributions were successfully obtained, indicating that the bulky adamantyl groups effectively protected the carbon–nitrogen double bond (CN) from the nucleophilic attack of the initiators and the propagating chain ends. The stability of the propagating chain end of poly­(<b>1</b>) was confirmed by the quantitative efficiencies in the postpolymerization and the sequential copolymerization with <i>tert</i>-butyl methacrylate. A poly­(4-formylstyrene) was quantitatively formed by the acidic hydrolysis reaction of the <i>N</i>-adamantylimino groups of the poly­(<b>1</b>). The resulting poly­(<b>1</b>) and poly­(<b>2</b>) showed significantly high glass transition temperatures (<i>T</i>_g) at 257 and 209 °C, respectively, due to the bulky and stiff adamantyl substituents. It was also found that the substituted position of adamantane unit and the linkage between polystyrene backbone and adamantyl groups played very important roles to determine the <i>T</i>_g values of the substituted polystyrenes

Experimental Formulation of Photonic Crystal Properties for Hierarchically Self-Assembled POSS–Bottlebrush Block Copolymers

Rodlike “POSS–bottlebrush block copolymers” (POSSBBCPs) containing crystalline polyhedral oligomeric silsesquioxane (POSS) pendants in A block and amorphous polymeric grafts in B block were utilized to create one-dimensional (1D) photonic crystals (PCs). 3-(12-(<i>cis</i>-5-Norbornene-<i>exo</i>-2,3-dicarboximido)­dodecanoylamino)­propyl­heptaisobutyl POSS (<b>NB-A16-POSS</b>, M_A) and <i>exo</i>-5-norbornene-2-carbonyl-end poly­(benzyl methacrylate) (<b>NBPBzMA</b>, M_B) were employed in sequential ring-opening metathesis polymerization to afford poly­[3-(12-(<i>cis</i>-5-norbornene-<i>exo</i>-2,3-dicarboximido)­dodecanoylamino)­propyl­heptaisobutyl POSS]-<i>block</i>-poly­(<i>exo</i>-5-norbornene-2-carbonylate-<i>graft</i>-benzyl methacrylate)­s, <b>P­(NB-A16-POSS)-</b><i><b>b</b></i><b>-P­(NB-</b><i><b>g</b></i><b>-BzMA)</b>s, with well-modulated block compositions (<i>f</i>_A = 34, 50, and 67 wt %) and overall degrees of polymerization (DP = 323–939). The <b>P­(NB-A16-POSS)-</b><i><b>b</b></i><b>-P­(NB-</b><i><b>g</b></i><b>-BzMA)</b>s hierarchically self-assembled to form highly ordered 1D PC films with periodic lamellar arrays that can reflect visible light with particular wavelengths. Their reflectance bandwidths, reflectivities, and ranges of peak reflectance wavelnegth (λ_peak) were largely dependent on the block composition. The 1D PC films based on lamellar <b>P­(NB-A16-POSS)-</b><i><b>b</b></i><b>-P­(NB-</b><i><b>g</b></i><b>-BzMA)</b>s demonstrated the capability of formaulation of λ_peak as linear functions of initial polymerization parameter ([M]₀/[I]₀)

Polyviologen Hydrogel with High-Rate Capability for Anodes toward an Aqueous Electrolyte-Type and Organic-Based Rechargeable Device

A highly cross-linked polyviologen hydrogel, poly­(tripyridiniomesitylene) (PTPM), has been designed as an anode-active material. It displays a reversible two-electron redox capability at −0.4 and −0.8 V vs Ag/AgCl in an aqueous electrolyte. The PTPM layer coated on a current collector by electropolymerization via a 4-cyanopyridinium electro-coupling reaction demonstrates a rapid charging-discharging reaction with a redox capacity comparable to that obtainable using the formula weight-based theoretical density, because of the combination of the redox-active viologen moieties built into the hydrogel. A test cell that has been fabricated using the developed PTPM anode, a poly­(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) (PTAm)-based cathode, and an aqueous electrolyte exhibits a discharging voltage of 1.1 and 1.5 V, and has proven its ability to be recharged more than 2000 times

Precise Synthesis of Bottlebrush Block Copolymers from ω‑End-Norbornyl Polystyrene and Poly(4-<i>tert</i>-butoxystyrene) via Living Anionic Polymerization and Ring-Opening Metathesis Polymerization

A facile and efficient synthetic grafting-through strategy for preparing well-defined bottlebrush block copolymers (BBCPs) was developed through a combination of living anionic polymerization (LAP) and ring-opening metathesis polymerization (ROMP). ω-End-norbornyl polystyrene (NPSt) and poly­(4-<i>tert</i>-butoxystyrene) (NP<i>t</i>BOS) were synthesized by LAP using terminator of chlorine moiety containing silane-protecting amine and coupled with a subsequent amidation using norbornyl activated ester. Bottlebrush homopolymers of NPSt were obtained by ROMP with ultrahigh molecular weights (MWs, <i>M</i>_w = 2928 kDa) and narrow molecular weight distributions (MWDs, <i>Đ</i> = 1.07) at high degree of polymerizations (DP_w = 1084). Well-defined BBCPs with ultrahigh MWs (<i>M</i>_w ∼ 3055 kDa) and narrow MWDs (<i>Đ</i> ∼ 1.13) were synthesized through sequential ROMP of NPSt with NP<i>t</i>BOS. The effect of ultrahigh MWs was investigated by self-assembly of the BBCPs in which the phase-separated BBCPs presented periodic lamellar structures and exhibited structural colors from blue to pink