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TA–Fe@PS-c-PAN NPs were synthesized via a typical FNP procedure. During the process, the water solution containing Fe3+ and the organic solution containing polymer and TA diffused into each other under turbulent mixing. As a result, the hydrophobic TA–Fe complex quickly formed and co-assembled into TA–Fe@PS-c-PAN NPs. After carbonization, carbon materials with uniformly dispersed metal NPs were finally and used as effective catalysts for oxygen reduction and evolution reactions.
This article describes the self-assembly of Fmoc-dipeptides comprising α-methyl-L-phenylalanine. The position and number of methyl groups introduced onto the α carbons of the Fmoc-dipeptides as α-methyl-L-phenylalanine have a marked influence on the morphology of supramolecular nanostructures and the hydrogel formation ability.
Two series of fluorescent glycopolymers (boronic acid derivatives, PG-PFE, and borate derivatives, PG-PFW) were synthesized through different methods. Compared with the PG-PFE samples, the PG-PFW samples had a higher grafting ratio due to the highly efficient Williamson reaction. The fluorescent glycopolymers possessed good water solubility, low cytotoxicity and selective responsiveness toward H2O2. Meantime, the fluorescent glycopolymers were imaged only in cellular mitochondria based on the fact that endogenous H2O2 is mainly distributed in cellular mitochondria.
In this study, we synthesized and characterized cyclodextrin-based nanoparticles (CDNPs) by polyaddition reactions using epichlorohydrin and three different type of CDs (α-, β-, and γ-CD). We found that cyclodextrin tended to cover surface of our nanoparticles; while epichlorohydrin network enlarged when weight ratio of epichlorohydrin/cyclodextrin increased. Our CDNPs demonstrated a very high loading ratio against α-mangostin (MGS), and getting close to 1:1 ratio.
The halogenated polyhedral oligomeric silsesquioxane (POSS) fillers can increase the refractive indices (RIs) of the films. In particular, the degree of increases was larger than those estimated by the theoretical prediction, suggesting that accumulation of polymer chains around the POSS filler plays a key role in the increasing effect. Moreover, critical losses of thermal and mechanical properties were hardly observed. Preparation without the conventional sol‒gel method for the single-molecule-type filler with high-RI polymer hybrids based on the chain assembling can be demonstrated.
The thermocompression bonding of conductive polymer films was investigated to achieve a flexible wiring and packaging technique for flexible electronics. Conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films were successfully bonded together by thermocompression, especially through surface activation treatment using ultraviolet light irradiation. After thermocompression, the PEDOT:PSS films maintained their ohmic electrical conductivity even through the adhered interface. The surface state analysis of the PEDOT:PSS indicated that the oxidized species were generated after the surface activation process. These chemical species can interact each other and provide robust bonding interfaces.
This work presents a method on tailoring open pores on the patterned surface of polyethersulfone membrane prepared by the phase separation micromolding. By modifying both the thermodynamics of the casting solution and the dynamics of solvent/nonsolvent demixing, micropatterned membrane with average surface open pores in the diameter of 1095 nm and porosity as high as 31.4% was achieved. The size and number of pores were different depending on their locations on the patterned surface, which was caused by different solvent/nonsolvent demixing dynamics resulting from the physical discontinuity of micro-patterned membranes.
To precisely design microwrinkles on a biomimetic hydrogel, a two-step photocrosslinking process with VIS and UV irradiation was developed. Photocurable gelatin was first crosslinked with VIS light in the presence of the water-soluble radical generator to form thick bulk gels. Next, the top surface of the gels was irradiated with UV light in the presence of surface-coated water-insoluble radical generator. This two-step photocrosslinking process enabled to independently control the elastic moduli of the surface and the bulk lower than 100 kPa and to generate several-micron-scale wrinkles on the soft hydrogels.
A novel method for preparing coal gasification fine slag (CGFS) samples utilized as a reinforcing filler for the SBR matrix through an efficient pneumatic separation technique has been demonstrated. The superior filler–rubber interfacial interaction can contribute to significant reinforcement in the comprehensive performances of composites by the addition of CGFS series fillers into the SBR matrix. CGFS particles have great potential for application in rubber composites, and a new strategy of using CGFS as fillers has been established.
The dilute solution properties of poly(d,l-lactide)s (PDL50) with a weight-averaged molar mass (Mw) ranging from 0.154 × 104 to 75.7 × 104 g mol−1 are thoroughly studied in tetrahydrofuran at 25 °C by static light and small-angle X-ray scattering and intrinsic viscosity ([η]) measurements. The Mw dependences of 〈S2〉z1/2 and [η] are quantitatively described by the wormlike cylinder with stiffness parameter λ−1 = 2.9 nm, indicating that the PDL50 chain behaves as a typical flexible polymer but is essentially 1.6−2.1 times stiffer than polystyrene and poly(methyl methacrylate).
Polymeric micelles based on amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone)-b-poly(ethylene oxide)(PEO-b-PCL-b-PEO) triblock copolymers improved the solubility of caffeic acid phenethyl ester (CAPE) in aqueous media. Further on, the grafting of pendant cinnamyl moieties to the PCL block enhanced the compatibility between CAPE and the micellar core, thus increasing the encapsulation efficiency and reducing the burst release effect as compared to those of micelles with an unmodified PCL core.
The interfacial adhesion between olefinic double bond- or hydroxyl-terminated telechelic polypropylenes (PPs) and carbon fibers was studied to determine the potential of the telechelic PPs as a candidate for PP matrix resin-coupling agents for carbon fiber-reinforced PP composites. The hydroxyl-terminated PP showed higher interfacial shear strength than that of commercial PP and olefinic double bond-terminated PP. The hydroxyl-terminated PP could be used as a novel coupling agent of the PP matrix.
A cyclic block copolymer allows feasible fabrication of porous films through designed interaction between its macromolecular arms. The morphology of pores is directly determined by the structural features of the block copolymer and can be easily tuned by modification of the length of its ring and arms.
The correlation between mechanical properties and structural changes upon uniaxial stretching was studied by atomic force microscopy observations and two-dimensional small-angle X-ray scattering measurements. For this purpose, coated layers composed of di- and tri-block copolymer blends were prepared by solution coating at different drying temperatures. The packing regularity of spherical microdomains in the stretching direction was enhanced with stretching. We could correlate fracture of the block copolymer film having spherical microdomains with the completion of stretching-induced ordering of spheres in the stretching direction, which sensitively depended on the drying temperature.
Photopolymerization of dodecyl acrylate was conducted using methyl phenylglyoxylate as an initiator. Most polymers had either an acryloyl group or a benzoyl group at one of the chain ends. We investigated the initiation pathways and found out that methyl phenylglyoxylate initiated photopolymerization only by Norrish type II processes.
Transient elongational viscosity for polypropylene (PP)/low-density polyethylene (LDPE) blends was evaluated. Because deformed LDPE droplets act as rigid fibers due to its strain hardening, the blends show a strain hardening behavior. The growth curves are, however, affected by their viscosity ratio. These behaviors are calculated by the Phan–Thien Tanner model by assuming a symmetric geometry with a periodic structure. Based on the simulation, we propose an appropriate LDPE to modify the processability, at which the strain hardening in the elongational viscosity is required.
The osmotic pressure during the gelation process below the overlapping concentration of prepolymers was investigated using a series of model polymer gels, namely, tetra-polyethylene glycol gels. The osmotic pressure decreased during the gelation reaction and was constant after the sol–gel transition, suggesting that the clusters grow and fill the system, at the sol–gel transition point. This representation of the sol–gel transition at the overlapping condition of the critical clusters corresponds well to the aggregation process prediction.
Low-modulus polypropylene (LMPP) with controlled stereoregularity showed elastic recovery. To understand the underlying mechanism, changes in the morphology of LMPP under cyclic uniaxial elongation were investigated using in situ SAXS and WAXD. During the first cycle, the undulating structure of the crystal lamellae is large, and fragmentation of the lamellae occurs. On the other hand, during the second cycle, the little fragmentation of the lamellae occurs and that only the lamellae were rotating under elongation. Based on these results, lamella fragmentation has a significant effect on the elastic-recovery rate.
Visible light-curable alginate was prepared by coupling alginate with furfurylamine. The prepared furfuryl alginate (F-Alginate) underwent gelation in the presence of a photosensitizer under visible light irradiation. The mechanical and release properties of the visible light-induced gel were similar to that of conventional Ca2+-induced cross-linked alginate. The release rate of encapsulated substances depended on their molecular weight. Cell growth was enhanced in response to a sustained release of insulin-like growth factor-1 from the F-Alginate hydrogel.
To understand the roles of mechanical and structural factors in the extracellular matrix on cancer cell migration, elasticity/porosity-tunable gel matrices of gelatinous microfibers were developed. The elasticity of fibers and the porosity of matrix were tuned with photocrosslinking conditions and degree of interfiber bonding, respectively. Highly malignant MDA-MB-231 cells showed the highest degree of MMP-independent invasion into the matrix composed of fibers with a Young’s modulus of 20 kPa and a low degree of interfiber bonding, while nontumorigenic MCF-10A cells did not show invasive behavior under the same matrix conditions.
A π-conjugated polymer based on thienylene–vinylene–thienylene (TVT) units can form a thermotropic liquid-crystalline (LC) mesophase over a wide temperature range. Thermal annealing at LC temperatures strongly enhanced hole mobilities in organic field-effect transistors (OFETs) owing to improved molecular ordering. Because of its thermoplasticity, the TVT-based π-conjugated polymer can also be processed into semiconducting fine microfibers and serve as a charge transport pathway in microfiber OFETs.
Hydrophilic alternating copolymers (P(11EO/MA)m) of methoxy poly(ethylene glycol) allyl ether (11EO) and maleic anhydride (MA) were prepared via controlled radical polymerization. The MA units in P(11EO/MA)m were hydrolyzed to prepare pendant carboxylic acid group-containing polymers (P(11EO/MH)m). Furthermore, an amphiphilic diblock copolymer (P(11EO/MH)m-PSn) was prepared via block copolymerization of styrene using P(11EO/MH)m as a macro-chain transfer agent. The association behavior of P(11EO/MH)m-PSn in water was also investigated.
Active, hydrophilic, piezoelectric PLLA surface is formed by correlating processing parameters with etching and annealing as post-processing steps. Optimal design is obtained after uniaxial drawing of films for five times their length at 90 °C with 40 mm min−1 drawing rate and post-processing heat treatment at 140 °C followed by surface alkaline etching. We designed active PLLA film with high potential for intensive interactions with cells, very important for further biomedical applications, including exploring the effect of piezoelectricity on cell proliferation.
Herein, several synthetic procedures for the synthesis of uniform PEGs were compared. The importance of SEC as analytical method for the determination of the precise structure and purity of uniform PEGs was shown by means of simple symmetry peak analysis, revealing that SEC can detect contaminations of only 2% of oligomers with only one repeat unit difference.
The epoxydized soybean oil grafted with CTBN (ESO-g-CTBN) was synthesized from ring opening reaction between epoxide group and carboxyl group. The ESO-g-CTBN help to improve the fracture toughness of epoxy resin by the mechanism as shown in the figure.
Schwiertz et al. report on the synthesis of miktoarm star polymers based on polypept(o)ides by nucleophilic ring opening polymerization of N-carboxyanhydrides. The reported procedures allow for precise control over chain length, number of arms and end group functionality.
By virtue of “core first” method, ABC star quaterpolymers were controllably synthesized by combination of controlled polymerization and thiolactone chemistry. The miktoarm stars were responsive to temperature, pH, CO2, O2 and oxidation, and thus the phase transition temperature, size and morphology of copolymer assemblies could be efficiently tuned via adopting a single stimulus or combined stimuli.
The sulfur-containing styrene derivative, 4-methylenethiochromane (META), was subjected to anionic copolymerization with isoprene (Ip) modified with different additives. The reactivity of META can be effectively regulated with additives; thus, the regulation of the alternating or gradient copolymerization of META and Ip was facilely realized through the use of additives.
An efficient and straightforward strategy for the synthesis of uniform, sequence-defined oligo(ester-amide-ester)s via sequential nucleophilic substitution reactions and Passerini reaction was developed. The side groups could be easily regulated by the Passerini reaction of different aldehydes. The synthesis of uniform, symmetrical, long-chain oligomers was further demonstrated by an iterative approach. The DIC/DPTS-mediated polycondensation of the α,ω-hydroxy carboxylic acids as the sequence-defined oligomer afforded high-molecular-weight periodic poly(ester-amide-ester)s. The thermal properties of these oligo/poly(ester-amide-ester)s were also examined.
Well-defined poly(arylene ether sulfone)-b-polylactides (PES-b-PLAs) were successfully synthesized and their microphase separation behavior was investigated. PES was obtained via chain growth condensation polymerization, and subsequent end group modification followed by ring opening polymerization of d,l-lactide produced the diblock copolymers. By small-angle X-ray scattering experiments in bulk, the formation of ordered morphologies including spherical, cylindrical, gyroidal, and lamellar was observed. An effective interaction parameter at 150 °C was roughly estimated as 0.12 for the first time in engineering plastic-containing block copolymers.
Alkali metal carboxylates, which are readily available and widely used as food additives, were found to promote the ring-opening polymerization (ROP) of trimethylene carbonate (TMC) to produce poly(trimethylene carbonate) (PTMC). The sodium acetate-catalyzed ROP of TMC proceeded in the presence of an alcohol initiator under solvent-free conditions, even at very low catalyst loadings of 0.01–0.0001 mol%. This ROP system enabled the synthesis of PTMCs with predicted molecular weights ranging from 2400 to 11 700 g mol−1 and narrow dispersities (~1.23).
This study describes the production of the amphiphilic bioresorbable polymers sorbitan–PLA and PEG–PLA in a single reactor. This method aims to simplify the separation process and reduce purification costs while increasing the chemical yield. The obtained mixtures could stabilize squalene/water interfaces, resulting in a double-dispersion structure that is favorable for encapsulation in sustained delivery applications.
Based on the mechanism of cellular formation, the cellular formation and postcuring process were separated in this paper. First, the foamed sheets were rested at room temperature for 20 min. Then, the foamed sheets were fully vulcanized in a plate vulcanizing press at 165 °C for 8 min. A novel method of preparing microcellular silicone rubber foams without surface defects has been successfully created.
Long-chain-branched poly(aryl ether sulfone)-poly(tetrahydrofuran) multiblock copolymers composed of hard linear and soft branching segments were synthesized from bromo-terminated poly(tetrahydrofuran) and hydroxy-terminated poly(aryl ether sulfone). Optimization of the polymerization conditions afforded soluble powder at a reaction concentration of 7 wt%. Microphase-separated morphology was observed for the branched multiblock copolymers. Compared with the corresponding linear multiblock copolymer, the branched polymer chains in the soft domains become less entangled and more reminiscent of hyperbranched architectures, whereas the overall chain entanglements are increased due to the long-chain-branched structure.
The polymerization and crystallization of polyamide 6 (PA6) via anionic polymerization was observed using a combination of in situ wide-angle X-ray scattering (WAXS), temperature measurement, and real-time visualization at 119–182 °C. In-situ WAXS discriminated between polymerization and the crystallization of PA6. The WAXS results indicated that polymerization was fast at 139–155 °C, and crystallization was fast at 148–155 °C. The crystallinity of PA6 decreased with increasing temperature. We concluded that molding temperatures between 148 and 155 °C were suitable for high productivities of PA6 with good properties.
We introduce a facile method to convert the bromine end of the polymer into a hydroxyl group. For this, bromine-terminated polystyrene (PS-Br) was prepared by atom transfer radical polymerization. The bromine groups of the PS-Br could be directly converted to hydroxyl groups by using Ag+ as the Lewis acid in water/acetone. The conversion yield was investigated by 1H nuclear magnetic resonance spectroscopy, high-performance liquid chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
Vinylcycloalkanes with 12-, 15-, and 21-membered rings were synthesized from commercially available cycloalkanones or cycloalkyl carboxylic acids derived from malonate and ω-bromo-α-alkenes. Pd complexes with diimine ligands promoted the isomerization polymerization of vinylcycloalkanes with 15- and 21-membered rings to afford polymers having cycloalkylene groups in the main chain. Vinylcycloheneicosane with a 21-membered ring afforded polymers with Mn up to 9700, whereas vinylcycloalkanes with smaller ring sizes (8- and 12-membered rings) yielded oligomers with Mn = 720–1600.
A new nickel diphosphine catalyst was synthesized and evaluated for Suzuki–Miyaura cross-coupling polymerization. The diphosphine is comprised of two electronically and sterically distinct phosphine donors, a PPh2 group and a PEt2 group. The catalyst was employed to bring about controlled polymerization of a 3-hexylthiophene monomer to afford poly(3-hexylthiophene). The catalyst was particularly effective for bringing about this polymerization in the presence of excess free ligand. The catalyst resting state was also probed using NMR spectroscopy and an externally initiated catalyst.
The solubility of thermostable alkyl phosphate ester copper complexes in poly(alkyl methacrylate) has been investigated for use as near-infrared-absorbing dyes. 2-Ethylhexyl methacrylate solutions of the 2-ethylhexyl phosphate copper complex and isodecyl phosphate copper complex maintained their transparency even after polymerization, so these two copper complexes show good solubility in poly(2-ethylhexyl methacrylate). Both of the resin plates have visible light transmittance of above 80% and solar direct transmittance of below 50% from spectral transmission. Thus, these resin materials are suitable for window materials that require heat-shielding properties and transparency.
Photoswitchable and interconvertible cationic/radical copolymerization was investigated by combining a Lewis acid-catalyzed cationic polymerization with a photoinduced electron/energy transfer (PET)-reversible addition-fragmentation transfer (RAFT) polymerization, in which the dormant terminal group of the RAFT polymerization was employed as the dual mediator for cationic and photoradical polymerizations. Zinc porphyrin complex (ZnTPP) as the photoredox catalyst and bulky boron-based Lewis acid, B(C6F5)3, was successfully combined to induce the concurrent and interconvertible cationic/radical copolymerization of vinyl ether and methyl acrylate under visible light irradiation.
A new thermally latent cocatalyst, based on 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), has been specifically designed for “on-demand” synthesis of polyurethanes in the presence of DBTL as catalyst. This nitrophenyl-based isocyanurate cocatalyst exhibited a low cleavage temperature keeping the system almost inactive at 20 °C and allowing fast polymerization only after increasing temperature up to 60 °C by the release of active DBN.
Mechanical properties of rubber nanocomposites are believed to closely related to the chain dynamics at the interface with fillers. We here tackle this hypothesis combining traditional rheological measurements with our published results obtained by a modern technique of interfacial sensitive spectroscopy.
The block glycopolymers with specific arrangement of sugar ligand and electric charges were synthesized via RAFT living radical polymerization, where the block polymers were efficiently obtained using two orthogonal reactions of Huisgen and thiol-epoxy ring opening reactions. The molecular recognition abilities of the block glycopolymers was examined.
Controlled cationic cyclopolymerizations of divinyl ethers with cyclohexene, norbornene, norbornane, cyclic acetal, or adamantane moiety were carried out. High-molecular-weight star-shaped cyclopolymers were synthesized by the reaction of the formed living cyclopolymers with a small amount of divinyl ether crosslinking agent. Glass transition temperatures (Tg’s) of both the cyclopolymers and star-shaped cyclopolymers were as high as 145−229 oC. Methacrylate-terminated end-functionalized star-shaped cyclopolymers were synthesized by the functionalized initiator-based living cationic cyclopolymerization of divinyl ethers followed by the chain linking reactions among the formed living cyclopolymers with divinyl ether crosslinker. The obtained end-functionalized star-shaped cyclopolymers were subjected to thermal crosslinking reaction to give star-shaped cyclopolymer networks with film-forming ability.
Pd-initiated polymerization of diazoacetates containing oligo(ethylene glycol)-substituted cyclotriphosphazenes was conducted to yield carbon-carbon main chain polymers bearing an oligo(ethylene glycol)-substituted cyclotriphosphazene on every main chain carbon atom. The resulting organic–inorganic poly(substituted methylene)s were found to show an LCST-type phase separation in aqueous media, and thus their thermosensitive behavior was evaluated by turbidity measurements.
We synthesized poly(bisphenol A-co-ephichlorohydrin)–titanium phosphonate clusters (Ti4P3: [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·thf; Ti4P4: [Ti(OiPr)(acac)(O3PPh)]4; Ti7P6: Ti7(μ3-O)2 (OiPr)6(μ-OiPr)6(O3PBnBr)6). From the result of swelling test using tetrahydrofuran, Ti7P6 cluster showed highest cross-linking efficiency.
Polypeptides containing periodic aromatic residues, 4-aminobenzoic acid (Abz), in their main chains were synthesized via papain-catalyzed chemoenzymatic polymerization of tripeptide ester monomers under moderate conditions in aqueous buffers. The secondary structures of the Abz-containing polypeptides were investigated by IR and wide-angle X-ray diffraction analysis. The WAXD profile of poly(GlyAbzGly) was similar to that of polyGly, whereas poly(AlaAbzAla) adopted a sheet-like structure similar to the β-sheet of polyAla.
We synthesized cellulose nanofiber (CNF) modified with 9,9′-bis(aryl)fluorene, possessing cardo moieties (BCNF), and evaluated the properties of its polyamide 6/66 (PA) composites. As a result, it was revealed that BCNF was well dispersed in PA and had a strong reinforcing effect—even in a temperature range above the glass transition temperature—compared with unmodified CNF. This is attributed to the improvement of the interface affinity between BCNF and PA derived from the bulky and hydrophobic structure of BPFG.