Rod-Like Amphiphile of Diblock Polyisocyanate Leading to Cylindrical Micelle and Spherical Vesicle in Water

The self-assembling property of an amphiphilic rod–rod diblock copolymer has been demonstrated using poly­(<i>n</i>-hexyl isocyanate)-<i>block</i>-poly­(2,5,8,11-tetraoxatridecyl isocyanate) (<b>PHIC-</b><i><b>b</b></i><b>-PEOIC</b>) with different degrees of polymerization for the <b>PHIC</b> and <b>PEOIC</b> segments. The critical aggregation concentrations (CAC) of <b>PHIC-</b><i><b>b</b></i><b>-PEOIC</b> decreased with the increasing fraction of the hydrophobic <b>PHIC</b> segment. The relation between the hydrodynamic radius (<i>R</i>_h) and the <b>PHIC</b>/<b>PEOIC</b> ratio differed from that for the radius of gyration (<i>R</i>_g). The self-assembled <b>PHIC-</b><i><b>b</b></i><b>-PEOIC</b> was stable in various polymer concentrations. The ρ parameter (<i>R</i>_g/<i>R</i>_h) strongly suggested that the macromolecular architecture was a cylindrical micelle for <b>PHIC</b>_<b>13</b><b>-</b><i><b>b</b></i><b>-PEOIC</b>_<b>41</b> (ρ = 1.63) and a spherical vesicle for <b>PHIC</b>_<b>22</b><b>-</b><i><b>b</b></i><b>-PEOIC</b>_<b>36</b> (ρ = 1.09) and <b>PHIC</b>_<b>31</b><b>-</b><i><b>b</b></i><b>-PEOIC</b>_<b>31</b> (ρ = 1.09). Transmission electron microscope (TEM) images closely agreed with the structures of the cylindrical micelle and spherical vesicle, which were expected based on the ρ parameter

Synthesis of High Molecular Weight and End-Functionalized Poly(styrene oxide) by Living Ring-Opening Polymerization of Styrene Oxide Using the Alcohol/Phosphazene Base Initiating System

The ring-opening polymerization (ROP) of styrene oxide (SO) was carried out using 3-phenyl-1-propanol (PPA) as the initiator and a phosphazene base, 1-<i>tert</i>-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2Λ⁵,4Λ⁵-catenadi(phosphazene) (<i>t</i>-Bu-P₄), as the catalyst at room temperature. The polymerization proceeded in a living manner, which was confirmed by the kinetic and chain extension experiments, to produce the poly(styrene oxide) (PSO) with a controlled molecular weight (5200–21 800 g mol^–1) and narrow molecular weight distribution (<1.14). The ¹H NMR and MALDI-TOF MS measurements of the obtained PSO clearly indicated the presence of the PPA residue at the chain end. In addition, the <i>t</i>-Bu-P₄-catalyzed ROP of SO with functional initiators, such as 4-vinylbenzyl alcohol, 5-hexen-1-ol, 6-azide-1-hexanol, and 3-hydroxymethyl-3-methyloxetane, successfully afforded the corresponding end-functionalized PSO with precise molecular control. The <i>t</i>-Bu-P₄-catalyzed ROP of SO proceeded through the β- and α-scissions as the main and minor ring-opening manners on the basis of the microstructure of the PSOs analyzed by the ¹³C NMR measurement, which was clarified in the model reactions corresponding to the initiation and propagation. For the thermal analysis of PSO, the glass transition temperature and 5% weight loss temperature were found to be 34 and 310 °C, respectively

Diphenyl Phosphate as an Efficient Acidic Organocatalyst for Controlled/Living Ring-Opening Polymerization of Trimethylene Carbonates Leading to Block, End-Functionalized, and Macrocyclic Polycarbonates

The ring-opening polymerization (ROP) of cyclic carbonates with diphenyl phosphate (DPP) as the organocatalyst and 3-phenyl-1-propanol (PPA) as the initiator has been studied using trimethylene carbonate (TMC), 5,5-dimethyl-1,3-dioxan-2-one, 5,5-dibromomethyl-1,3-dioxan-2-one, 5-benzyloxy-1,3-dioxan-2-one, 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one, and 5-methyl-5-propargyloxycarbonyl-1,3-dioxan-2-one. All the polymerizations proceeded without backbiting, decarboxylation, and transesterification reactions to afford polycarbonates having narrow polydispersity indices. In addition, 6-azido-1-hexanol, propargyl alcohol, and <i>N</i>-(2-hydroxyethyl)­maleimide were used as functional initiators for the DPP-catalyzed ROP to produce the end-functionalized poly­(trimethylene carbonate)­s. For further modification of the azido end-functionlized polycarbonate, the macrocyclic poly­(trimethylene carbonate) was synthesized by the intramolecular click cyclization of the α-azido, <i>ω-</i>ethynyl poly­(trimethylene carbonate). The DPP-catalyzed ROP was applicable for the block copolymerization of TMC and <i>δ-</i>valerolactone or <i>ε-</i>caprolactone to afford poly­(trimethylene carbonate)-<i>block</i>-poly­(δ-valerolactone) and poly­(trimethylene carbonate)-<i>block</i>-poly­(ε-caprolactone), and for that of TMC and l-lactide using DPP coupled with 4-dimethylaminopyridine without quenching to produce poly­(trimethylene carbonate)-<i>block</i>-poly­(l-lactide)

B(C₆F₅)₃‑Catalyzed Group Transfer Polymerization of <i>N,N</i>-Disubstituted Acrylamide Using Hydrosilane: Effect of Hydrosilane and Monomer Structures, Polymerization Mechanism, and Synthesis of α‑End-Functionalized Polyacrylamides

The tris­(pentafluorophenyl)­borane- (B­(C₆F₅)₃-) catalyzed group transfer polymerization (GTP) of <i>N,N</i>-disubstituted acrylamide (DAAm) using a moisture-tolerant hydrosilane (H<i>Si</i>) as part of the initiator has been intensively investigated in this study. The screening experiment using various H<i>Si</i>s suggested that dimethylethylsilane (Me₂EtSiH) with the least steric bulkiness was the most appropriate reagent for the polymerization control. The chemical structure of the DAAms significantly affected the livingness of the polymerization. For instance, the polymerization of <i>N,N</i>-diethylacrylamide (DEtAAm) using Me₂EtSiH only showed better control over the molecular weight distribution, while that of <i>N</i>-acryloylmorpholine (MorAAm) with a more obstructive side group using the same H<i>Si</i> afforded precise control of the molecular weight as well as its distribution. Given that the entire polymerization was composed of the monomer activation, the <i>in situ</i> formation of a silyl ketene aminal as the true initiator by the 1,4-hydrosilylation of DAAm, and the GTP process, the polymerization mechanism was discussed in detail for each specific case, e.g., the B­(C₆F₅)₃-catalyzed polymerizations of DEtAAm and MorAAm and the polymerization of MorAAm using B­(C₆F₅)₃ and Me₃SiNTf₂ as a double catalytic system. Finally, the convenient α-end-functionalization of poly­(<i>N,N</i>-disubstituted acrylamide) (PDAAm) was achieved by the <i>in situ</i> preparation of functional silyl ketene aminals through the 1,4-hydrosilylation of functional methacrylamides, which has no polymerization reactivity in the Lewis acid-catalyzed GTP, followed by the Me₃SiNTf₂-catalyzed GTP of DAAms

Colorimetric Detection of Anions in Aqueous Solution Using Poly(phenylacetylene) with Sulfonamide Receptors Activated by Electron Withdrawing Group

A series of sulfonamide-conjugated poly­(phenylacetylene)­s with various electron withdrawing and donating substituents were designed and synthesized in order to develop a novel colorimetric probe for anions in water. The UV–vis absorption measurements, which were performed in an organic solvent to provide fundamental insights into the anion detection properties of these polymers, clarified that the colorimetric response ability is highly enhanced by the incorporation of strong electron withdrawing groups (EWG). Sulfonamide-conjugated poly­(phenylacetylene) with nitro groups, the strongest EWG, was therefore used for the detection of anions in an aqueous environment. In a solution containing up to 20% water, the polymer exhibited obvious color changes to anions including the biologically important carboxylates. On the basis of the NMR titration analysis, such a colorimetric response was confirmed to be based on the deprotonation event of the sulfonamide binding site, which was suggested to be essential for the detection of aqueous anions

Sub-10 nm Scale Nanostructures in Self-Organized Linear Di- and Triblock Copolymers and Miktoarm Star Copolymers Consisting of Maltoheptaose and Polystyrene

The present paper describes the sub-10 nm scale self-assembly of AB-type diblock, ABA-type triblock, and A₂B-type miktoarm star copolymers consisting of maltoheptaose (MH: A block) and polystyrene (PS: B block). These block copolymers (BCPs) were synthesized through coupling of end-functionalized MH and PS moieties. Small-angle X-ray scattering and atomic force microscope investigations indicated self-organized cylindrical and lamellar structures in the BCP bulks and thin films with domain spacing (<i>d</i>) ranging from 7.65 to 10.6 nm depending on the volume fraction of MH block (ϕ_MH), Flory–Huggins interaction parameter (χ), and degree of polymerization (<i>N</i>). The BCP architecture also governed the morphology of the BCPs, e.g. the AB-type diblock copolymer (ϕ_MH = 0.42), the ABA-type triblock copolymer (ϕ_MH = 0.40), and the A₂B-type miktoarm star copolymer (ϕ_MH = 0.45) self-organized into cylinder (<i>d</i> = 7.65 nm), lamellar (<i>d</i> = 8.41 nm), and lamellar (<i>d</i> = 9.21 nm) structures, respectively

Synthesis of Star- and Figure-Eight-Shaped Polyethers by <i>t</i>‑Bu‑P₄‑Catalyzed Ring-Opening Polymerization of Butylene Oxide

The synthesis of well-defined four-armed star-shaped poly­(butylene oxide) and figure-eight-shaped poly­(butylene oxide)­s (<i>s</i>-PBO and 8-PBO, respectively) with predicted molecular weights and narrow molecular weight distributions (<i>M</i>_w/<i>M</i>_ns) was achieved by the <i>t</i>-Bu-P₄-catalyzed ring-opening polymerization (ROP) of butylene oxide (BO). The <i>t</i>-Bu-P₄-catalyzed ROP of BO using 1,2,4,5-benzenetetramethanol as the initiator produced <i>s</i>-PBOs having number-average molecular weights (<i>M</i>_n,NMRs) ranging from ca. 4000 to 12 000 g mol^–1 and narrow <i>M</i>_w/<i>M</i>_ns of <1.03. Cleavage of the linkage between the initiator residue and PBO arms in <i>s</i>-PBO provided evidence for the homogeneous growth of each arm during the polymerization. The synthesis of 8-PBO was carried out through three reaction steps including (1) the synthesis of a PBO possessing two azido groups at the chain center ((N₃)₂-(PBO)₂) by the ROP of BO using 2,2-bis­((6-azidohexyloxy)­methy)­propane-1,3-diol as the initiator, (2) the introduction of an ethynyl group at the two ω-chain ends by etherification using propargyl bromide to give the ω,ω′-diethynyl poly­(butylene oxide) with two azido groups ((N₃)₂-(PBO-CCH)₂), and (3) the intramolecular click cyclization of (N₃)₂-(PBO-CCH)₂ using the copper­(I) bromide/<i><i>N,N</i>,N′,N″,N″</i>-pentamethyldiethylenetriamine catalyst in DMF under high dilution conditions. Size exclusion chromatography, FT-IR, and ¹H NMR measurements confirmed that the click reaction proceeded in an intramolecular fashion to give 8-PBOs having <i>M</i>_n,NMRs ranging from ca. 3000 to 12 000 g mol^–1 and narrow <i>M</i>_w/<i>M</i>_ns of <1.06. The viscosity property of <i>s</i>-PBO and 8-PBO was evaluated together with linear and cyclic PBOs (<i>l</i>-PBO and <i>c</i>-PBO, respectively). The intrinsic viscosity ([η]) of <i>l</i>-PBO, <i>c</i>-PBO, <i>s</i>-PBO, and 8-PBO decreased in the order of <i>l</i>-PBO > <i>s</i>-PBO > <i>c</i>-PBO > 8-PBO

Controlled/Living Ring-Opening Polymerization of Glycidylamine Derivatives Using <i>t</i>‑Bu‑P₄/Alcohol Initiating System Leading to Polyethers with Pendant Primary, Secondary, and Tertiary Amino Groups

The combination of <i>t</i>-Bu-P₄ and alcohol was found to be an excellent catalytic system for the controlled/living ring-opening polymerization (ROP) of <i>N</i>,<i>N</i>-disubstituted glycidylamine derivatives, such as <i>N</i>,<i>N</i>-dibenzylglycidylamine (DBGA), <i>N</i>-benzyl-<i>N</i>-methylglycidylamine, <i>N</i>-glycidylmorpholine, and <i>N</i>,<i>N</i>-bis­(2-methoxyethyl)­glycidylamine, to give well-defined polyethers having various pendant tertiary amino groups with predictable molecular weights and narrow molecular weight distributions (typically <i>M</i>_w/<i>M</i>_n < 1.2). The <i>t</i>-Bu-P₄-catalyzed ROP of these monomers in toluene at room temperature proceeded in a living manner, which was confirmed by a MALDI-TOF MS analysis, kinetic measurement, and postpolymerization experiment. The well-controlled nature of the present system enabled the production of the block copolymers composed of the glycidylamine monomers. The polyethers having pendant primary and secondary amino groups, i.e., poly­(glycidylamine) and poly­(glycidylmethylamine), respectively, were readily obtained by the debenzylation of poly­(DBGA) and poly­(BMGA), respectively, through the treatment with Pd/C in THF/MeOH under a hydrogen atmosphere. To the best of our knowledge, this report is the first example of the controlled/living polymerization of glycidylamine derivatives, providing a rapid and comprehensive access to the polyethers having primary, secondary, and tertiary amino groups

Synthesis of α‑, ω‑, and α,ω-End-Functionalized Poly(<i>n</i>‑butyl acrylate)s by Organocatalytic Group Transfer Polymerization Using Functional Initiator and Terminator

The α-functionalized (hydroxyl, ethynyl, vinyl, and norbornenyl), ω-functionalized (ethynyl, vinyl, hydroxyl, and bromo), and α,ω-functionalized polyacrylates were precisely synthesized by the <i>N</i>-(trimethylsilyl)­bis­(trifluoroethanesulfonyl)­imide (Me₃SiNTf₂)-catalyzed group transfer polymerization (GTP) of <i>n</i>-butyl acrylate (<i>n</i>BA). The α-functionalization and ω-functionalization were carried out using the functional triisopropylsilyl ketene acetal as the initiator (initiation approach) and 2-phenyl acrylate derivatives as the terminator (termination approach) for the organocatalytic GTP, respectively. All the polymerizations precisely occurred and produced well-defined end-functionalized poly­(<i>n</i>-butyl acrylate)­s which had predictable molecular weights and narrow molecular weight distributions. High-molecular-weight polyacrylates were easily synthesized using both approaches. In addition, the α,ω-functionalized (hetero)­telechelic polyacrylates were synthesized by the combination of the initiation and termination approaches. The structure of the obtained polyacrylates and degree of functionalization were confirmed by the ¹H NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS) measurements. The spectra of the ¹H NMR and MALDI-TOF MS showed that the end-functionalization quantitatively proceeded without any side reactions

Synthesis, Thermal Properties, and Morphologies of Amphiphilic Brush Block Copolymers with Tacticity-Controlled Polyether Main Chain

A series of brush block copolymers (BBCPs) consisting of poly­(decyl glycidyl ether) (PDGE) and poly­(10-hydroxyldecyl glycidyl ether) (PHDGE) blocks, having four different types of chain tacticities, i.e., [<i>at</i>-PDGE]-<i>b</i>-[<i>at</i>-PDEGE], [<i>at</i>-PDGE]-<i>b</i>-[<i>it</i>-PDEGE], [<i>it</i>-PDGE]-<i>b</i>-[<i>at</i>-PDEGE], and [<i>it</i>-PDGE]-<i>b</i>-[<i>it</i>-PDEGE], where the <i>it</i> and <i>at</i> represent the isotactic and atactic chains, respectively, were prepared by <i>t</i>-Bu-P₄-catalyzed sequential anionic ring-opening polymerization of glycidyl ethers followed by side-chain modification. The corresponding homopolymers, i.e., <i>at</i>-PDGE, <i>it</i>-PDGE, <i>at</i>-PHDGE, and <i>it</i>-PHDGE, were also prepared for comparison with the BBCPs. The PDGE homopolymers were significantly promoted in the phase transitions and morphological structure formation by the isotacticity formation. In particular, <i>it</i>-PDGE was found to form only a horizontal multibilayer structure with a monoclinic lattice in thin films, which was driven by the bristles’ self-assembling ability and enhanced by the isotacticity. However, the PHDGE homopolymers were found to reveal somewhat different behaviors in the phase transitions and morphological structure formation by the tacticity control due to the additional presence of a hydroxyl group in the bristle end as an H-bonding interaction site. The H-bonding interaction could be enhanced by the isotacticity formation. The <i>it</i>-PHDGE homopolymer formed only the horizontal multibilayer structure, which was different from the formation of a mixture of horizontal and tilted multibilayer structures in <i>at</i>-PHDGE. The structural characteristics were further significantly influenced by the diblock formation and the tacticity of the counterpart block. Because of the strong self-assembling characteristics of the individual block components, all the BBCPs formed separate crystals rather than cocrystals. The isotacticity always promoted the formation of better quality morphological structures in terms of their lateral ordering and orientation