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Increasing the toughness of poly(lactic acid) (PLA), i.e., simultaneously increasing both the tensile strength and ductility, remains a major challenge. In this study, fully bio-based PLA blends with polydecalactone (PDL)-grafted cellulose copolymer (CgPD) were prepared and comprehensively analyzed to enhance the toughness of the PLA matrix. The blends were found by FT-IR and solid-state 1H NMR to be physically intact and miscible at the sub-twenty-nanometer scale. The WXRD and DSC analyses indicated that the addition of the alkyl-branched CgPD imparts a more structurally disordered PLA mesophase state to the prepared PLA_CgPD bio-blends. UTM analysis was used to characterize the macroscopic mechanical properties of the PLA_CgPD bio-blends. Both the tensile strength and elongation properties were simultaneously improved with the addition of 1 wt% CgPD loading amount to PLA (PLA_CgPD1). This study experimentally demonstrates that the enhanced mechanical properties of PLA_CgPD1 are closely related to the existence of more ordered PLA mesophases induced by the introduction of an optimal amount of CgPD into the PLA matrix.

Alginate hydrogel with high stretchability and toughness was prepared using binary solvent system consisting of water and glycerol. The mechanical performance was achieved via conformational control for the alginate molecules using water/glycerol binary system. The conformational characteristics of the alginate chains in glycerol/water solution were systematically investigated by spectroscopic analysis and rheological approach. The glycerol in the solution deconstructed intra-hydrogen bonding of alginate molecules, resulting in an increase of chain flexibility and hydrodynamic volume. The flexible chains had more chance to be entangled with the neighboring chains. The inter-molecular entanglement effectively transferred the stress and hindered crack propagation. The study provides fundamental insight for the design of alginate hydrogel with high stretchability and toughness.

To optimize a dynamic network structure is a key feature for a supramolecular self-healing material capable of perfectly and repeatedly restoring its morphology and performance following a mechanically damaging event. Despite significant progress in self-healing supramolecular networks over the past few decades, many questions surrounding the dynamic responses of these networks during healing still remain. Herein, we present the self-healing behavior of a dual dynamic supramolecular network (DDN) consisting of a weak clustery supramolecular network and a strong dendritic supramolecular network simultaneously. The DDN is easily prepared by the complexation of linear and non-linear poly(e-caprolactone)s end functionalized with 2-ureido-4[1H]-pyrimidinone, which exhibits 100%-optical and 95%-mechanical healing efficiencies within 2 and 5 min, respectively, at 90 °C. In addition, the DDN film is shown to repeatedly self-heal ten times, even when damaged at the same position. DDN healing depends significantly on the density of the supramolecular network, and is specifically accomplished by the reassociation of hydrogen bonds between UPy moieties at the thermally swollen status of the dendritic network following the thermal disassembly of the clustery network. The DDN-coated nylon fabric exhibits excellent self-healing characteristics, which opens opportunities for creating scratch-protective materials.

To develop a novel magnetic adsorbent for the removal of endocrine-disrupting chemicals, mesoporous magnetic clusters (MMCs) functionalized with β-cyclodextrin (β-CD), henceforth denoted CD-MG, were prepared by a facile chemical strategy and were applied to bisphenol A (BPA) removal for the first time. Fourier-transform infrared spectroscopy and thermogravimetric analysis revealed that β-CD was successfully linked to the MMC surfaces. X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy confirmed that the morphologies and crystal structures of the MMCs were well preserved in CD-MG. A pseudo-second-order kinetic model and Langmuir isotherm model were used to describe the BPA adsorption behavior of CD-MG. The kinetic model yielded a BPA adsorption rate constant of 0.0367 g mg−1 min−1, while the isotherm model yielded a maximum BPA adsorption capacity of 52.7 mg g−1. Furthermore, CD-MG exhibited a good recovery efficiency of 84.5% in the reusability tests, even after four cycles. The fast adsorption kinetics, high adsorption capacity, and good recovery efficiency indicated that CD-MG could be an effective magnetic adsorbent for the removal of endocrine-disrupting chemicals.

Hierarchical manganese oxides with enhanced catalytic performance have been successfully synthesized via simple thermal annealing of manganese coordination polymer precursors, which is a facile, cost-effective, and environmentally benign preparation method. The resultant manganese oxide particles formed hierarchical structures with a starfish-like morphology and exhibited enhanced low-temperature SCR performance below 200 °C without dopants or supporting materials. In addition, the morphology, chemical states, crystal structure and acidity of manganese oxide catalysts prepared at different calcination temperatures were investigated. It is elucidated that enhanced SCR catalytic performance was strongly dependent on the hierarchical morphology of the catalysts.

Meta-aramid exhibits excellent chemical stability and mechanical strength owing to its rigid crystal structure. However, the crystal structure is destroyed when meta-aramid nanofibers (mANFs) are fabricated by electrospinning, which results in nanofibers with poor performance characteristics. Here, we present a facile solvent-assisted heat treatment for the efficient crystallization of mANFs. The optimal volume ratio of the co-solvent solution was determined to be 6:5:100 (DMAc:ethylene glycol:water), and the optimal crystallization temperature 120 °C. The crystallinity of the mANFs obtained under these optimized conditions (mANF-6-120) is higher than the crystallinity of mANFs heat-treated at 300 °C (mANF-HT). As a result, mANF-6-120 exhibits superior chemical stability and mechanical strength compared to mANF-HT. After immersion in DMAc for 48 h, the weight of mANF-6-120 is reduced to 28% of its original weight, whereas the relative remaining weight of mANF-HT is less than 8%. The value of Young’s modulus of mANF-6-120 is 1.7 times higher than that of mANF-HT. The crystallization process developed in this study requires less energy and is less expensive than the conventional high-temperature heat treatment process. The meta-aramid nanofiber mat obtained using the proposed process shows great promise for application to water purification and the treatment of polluted air.

We used a nanofiltration (NF) membrane process to produce purified aqueous sulfuric acid from copper-refining sulfuric acid wastewater. Wastewater generated from a copper-refining process was used to explore the membrane performances and acid stabilities of six commercial NF membranes. A combination of permeate flux, sulfate permeation, and metal ion rejection clearly showed that two polyamide membranes and a polyacrylonitrile-based membrane achieved recovery of a purified sulfuric acid solution. Acid-stability and long-term performance tests showed that the polyamide membranes were unsuitable for copper-refining wastewater treatment because of their low acid stabilities. In contrast, the polyacrylonitrile-based composite membrane showed excellent acid stability, and gave greater than 90% metal ion rejection, with the exception of calcium ions, for 430 d. We also evaluated the recovery performance in 1 ton/d pilot-scale process using wastewater from copper-refining process; 90% metal ion rejection was achieved, with the exception of calcium ions, even at 95% recovery rate.

We developed a stimuli-responsive poly(tetrafluoroethylene) (PTFE) microfiltration (MF) membrane by reversible conjunction of magnetite nanoparticles. We modified the magnetic particles with maleimide functional groups and attached them to a furan-modified PTFE membrane via a Diels–Alder (DA) cycloaddition reaction to prepare an anti-fouling membrane that responds to magnetism and temperature. The combined results of Fourier-transform infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy investigations clearly showed that the maleimide-modified magnetic nanoparticles were successfully synthesized and coupled with the furan-modified PTFE MF membrane by the DA reaction. The modified membrane produced a micro-vortex under a rotating magnetic field, and showed a high resistance to fouling with a water flux higher than 50% of initial flux even after 30 min in the fouling test, whereas the neat membrane had a water flux falling below 20% of initial flux in 30 min. Moreover, the magnetite nanoparticles were readily and repeatedly regenerated on the MF membrane surface using a thermally driven peel-and-stick process; 75% of the water flux was recovered, even after three fouling cycles.

This study aims to develop a simple, low-cost method for synthesis of highly branched polycaprolactone (hbPCL) for use as effective “green” plasticizers for poly(vinyl chloride) (PVC). We demonstrate the facile synthesis of hbPCL with tunable molecular architecture using glycidol as a branching monomer. A series of hbPCLs is prepared via one-pot, solvent-free copolymerization of e-caprolactone and glycidol, wherein the molecular architecture is readily controlled by varying the molar ratio of glycidol to e-caprolactone. Further, studying the kinetics of copolymerization reveals the preferential reaction of glycidol over e-caprolactone, resulting in a multiarm star-like copolymer after the ring-opening of the two monomers. The crystallization ability of hbPCL is found to gradually weaken with the introduction of the branching structure, and its molecular mobility is improved substantially by esterification with butyric anhydride, following which a maximum mobility is realized at an intermediate level of br...

Despite the several decades study of the confinement effect of the polymeric nanomaterials, how the confinement influences 1D polymeric fiber nanomaterials is little understood. Here, we report that confinement can render ultrathin polymeric fibers rigid. By observing the changes in the crystalline and amorphous morphologies of electrospun nylon-6 nanofibers with variations in diameter and shape, we reveal that their crystalline phase changes into highly packed, stable α phase when the diameter is smaller than 120 nm. In addition, the molecular motion of the amorphous chains is severely suppressed with decrease in nanofiber diameter, indicating that the amorphous chains are also closely packed, forming a rigid structure. Indeed, the change in chain topology by confinement suppressed the release of rhodamine B from the ultrathin nanofibers. These findings allow us new insights for the design and development of advanced 1D polymer nanomaterials.

We developed two-step thermoresponsive membranes that have two different lower critical solution temperatures. To achieve this, poly(2-dimethylaminoethyl methacrylate)-block-poly(N-isopropylacrylamide) (PDMAEMA-b-PNIPAM, PDN) was introduced into a polyethersulfone (PES) ultrafiltration membrane. The combined Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, attenuated total reflection Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy results showed that PDN was successfully synthesized, and introduced into the PES membrane. The hydration capacity changes showed that the PES membrane with introduced PDN (PES/PDN) was temperature responsive, and that its pore structure changed. Water flux and protein separation experiments showed that the permeation properties of the PES/PDN membrane effectively changed, and protein separation was achieved based on pore structure changes in response to temperature changes. In particular, PES/PDN containing 5% PDN compared to PES separated water and three types of protein with high efficiency via three clear separation steps, at 30, 50, and 70 °C. In addition, the thermoresponsive polymer block in the PES/PDN membrane improved the flux recovery ratio from 29% to 69%.

A series of ion-exchange membranes for vanadium redox flow batteries (VRBs) are prepared by filling the pores of a poly(tetrafluoroethylene) (PTFE) substrate with sulfonated poly(ether ether ketone) (SPEEK) and microporous Engelhard titanosilicate-10 (ETS-10). The effects of ETS-10 incorporation and PTFE reinforcement on membrane properties and VRB single-cell performance are investigated using various characterization tools. The results show that these composite membranes exhibit improved mechanical properties and reduced vanadium-ion permeabilities owing to the interactions between ETS-10 and SPEEK, the suppressed swelling of PTFE, and the unique ETS-10 framework. The composite membrane with 3 wt% ETS-10 (referred to as “SE3/P”) exhibits the best membrane properties and highest ion selectivity. The VRB system with the SE3/P membrane exhibits higher cell capacity, higher cell efficiency, and lower capacity decay than that with a Nafion membrane. These results indicate that this composite membrane has potential as an alternative to Nafion in VRB systems.

Mn-doped maghemite (γ-Fe2O3) particles were generated from a binary metal (Fe,Mn)-based metal–organic framework (MOF) via thermal decomposition under air. The X-ray photoelectron spectroscopy analysis revealed that the synthesis of Fe/Mn-MOF accompanied the reduction of the metal ions. The existence of Mn ions in this synthetic process leads to thermally stable maghemite particles under air. A temperature-induced structural phase transition from γ-Fe2O3 to α-Fe2O3 was observed through a mixed phase with another structure. Mn-doped γ-Fe2O3 and α-Fe2O3 exhibit superparamagnetic behavior. The sample annealed at 600 °C showed a mixed magnetic hysteresis loop indicating the existence of an intermediate structural phase between γ-Fe2O3 and α-Fe2O3 during the phase conversion from FeMn-MOF. The constructed Mn-doped iron oxides are active toward reducing nitric oxide with NH3. The NO conversion is 97% over Mn-doped γ-Fe2O3 calcined at 320 °C.

In this study, we developed a highly stretchable internally- and externally-plasticized (i.e., dually-plasticized) cellulose, which is composed of a polydecalactone (PDL)-grafted cellulose copolymer (CgPD) and a hyperbranched polycaprolactone (PCL) external plasticizer (HPC). To investigate the effect of molecular structure of PCL external plasticizers on the plasticization behavior of dually-plasticized celluloses, a linear PCL (LPC) and a star-shaped PCL (SPC) were prepared as control groups. It is observed that specific molecular interactions existed between CgPD and external plasticizers in the dually-plasticized celluloses (i.e., CgPD_LPC, CgPD_SPC, and CgPD_HPC, respectively). Especially, CgPD_HPC exhibited the lowest apparent activation energy (Ea= ∼128.8 kJ mol−1) required to achieve the plasticizing behavior, which resulted in an enhanced ductility (e = ∼136%) compared to those of the CgPD (e= ∼75%), whereas CgPD_LPC and CgPD_SPC displayed severely deteriorated values (e = ∼25 and ∼59%, respectively). In addition, the dually-plasticized cellulose bearing bulkier HPC exhibited further improved stretchability. These results comprehensively indicate that the highly-branched flexible segments of external plasticizer and structural uniformity induced by effective specific interactions between the plasticizing components play crucial roles in improving plasticization abilities of the dually-plasticized cellulose.

Glass transition dynamics are one of the most important characteristics with regards to governing the properties of polymers. Herein, we prepare pyrene-labeled and pyrene-doped flexible poly(vinyl chloride)s plasticized by ultra-small branched star poly(e-caprolactone) (L-PVC/USB-SPCL and D-PVC/USB-SPCL, respectively), and observe the changes in their fluorescence intensities with temperature to ascertain the actual glass transition behaviors of the polymer chains. Fluorescence spectroscopy measurements show that the D-PVC/USB-SPCLs have a single Tg, which is comparable to the Tg measured by differential scanning calorimetry (DSC). However, the L-PVC/USB-SPCLs exhibit a broad glass transition from the onset of Tg for the L-PVC/USB-SPCLs to the endset of Tg for the PVC chain itself (i.e., in the absence of USB-SPCL). In addition, the L-PVC/USB-SPCLs show a relatively low nonradiative decay degree compared to the D-PVC/USB-SPCLs. These results indicate that the labeled pyrene moieties along the PVC chains exhibited limited movement due to the cooperative reptation motion of the chains, even when the space for the polymer chain to move sufficiently is created by an increase in the free volume. As the USB-SPCL content increase in the flexible PVC, the fluorescence intensity reduction degrees of the various D- and L-PVC/USB-SPCLs decrease due to the polarity effect of USB-SPCL. However, in the case of the L-PVC/USB-SPCLs, when the USB-SPCL loading reach 40 phr, the fluorescence intensity reduction degree increases once again due to the dominance of the decrease in caging effect, which reveals that the labeled system, in which a fluorescent substance is directly attached to a polymer chain, allows identification of the motion of the polymer chain in a direct and sensitive manner.

While preparation of metal oxide from metal organic frameworks (MOFs) has been widely studied, crystal growth via thermal decomposition of MOFs in a confined space is rarely investigated. We demonstrate a confinement effect on the crystal growth via pyrolysis of MOFs at high temperature. Iron containing MOF (Fe-MIL-88A) was calcined inside a SiO2. The crystalline phase, particle size, morphology, and magnetic properties of the synthesized iron oxide were characterized; α-Fe2O3 tubular structures that consisted of nanoparticles (around 10 nm) were observed. Studies of the magnetic properties show enhanced magnetization with superparamagnetic behavior. These results indicate that space confinement during the thermal treatment in air at high temperature allows the synthesis of small nanoparticles and the preservation of initial morphology of MOF precursors, which cannot be obtained via heating of MOFs without shell under identical conditions.

Sulfonated poly(ether ether ketone) (SPEEK) is a potential polymer for replacing Nafion in vanadium redox flow batteries (VRBs). However, at a high degree of sulfonation, SPEEK displays high swelling, poor mechanical stability, and high vanadium crossover. In this study, to improve membrane performance, composite membranes of SPEEK and finely ground microporous AMH-3 (G-AMH-3) are prepared with various G-AMH-3 contents and investigated. The physicochemical and mechanical properties, vanadium permeability, and VRB single cell performance of these SPEEK/G-AMH-3 composite membranes are evaluated using various characterization techniques. Interactions between SPEEK and G-AMH-3, and the permselective property of G-AMH-3, result in the composite membranes exhibiting good mechanical properties and low vanadium crossover. Optimal composite membranes gave a VRB that produced a higher charge–discharge capacity, higher cell efficiency, and better capacity retention than that using Nafion. These results indicate that SPEEK-based composite membranes with improved membrane performance, lower vanadium crossover, and good single cell performance were successfully prepared by incorporating G-AMH-3.

Electrospun meta-aramid nanofibers are typically extremely vulnerable to dipolar aprotic solvents, such as DMAc, DMSO, and DMF. This low chemical stability has made practical application of such nanofibers difficult. In this work, meta-aramid nanofiber mats with a directional nature were electrospun and sequentially post-treated by salt removal and heat treatment to enhance chemical stability. The salt added to dissolve the meta-aramid in the solvent was completely removed from the meta-aramid nanofibers via repetitive washing. The salt-removed meta-aramid nanofiber mat displayed a glass transition behavior not observed in the pristine nanofiber mat. The crystalline structure of the salt-removed nanofiber mats was regenerated by heat treatment above its glass transition temperature, whereas heat-treated nanofiber mats with salt remained amorphous. The salt between the meta-aramid chains interrupted their rearrangement, indicating that, in the absence of salt, the chains could be arranged during heat treatment. Additionally, the sequential post-treatment induced the reforming of intermolecular hydrogen bonds between the chains; thus, the post-treated nanofiber mat exhibited enhanced mechanical and chemical stabilities, which was confirmed by survival of the meta-aramid nanofiber in DMAc. Furthermore, a surface-modified meta-aramid nanofiber mat showing hydrophobicity and superoleophobicity was fabricated by silanization with trichloro (1H,1H,2H,2H-perfluorooctyl) silane.

AMH-3 is a zeolite-like material with a three-dimensional uniform porous structure, layered structure, and abundant exchangeable cations. Herein, the use of AMH-3 to remove heavy metals present in aqueous solutions is investigated for the first time. Pristine AMH-3 and metal-sorbed AMH-3 were characterized with inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy (FE-SEM), 29 Si cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP MAS NMR) and X-ray diffraction (XRD). The removal of heavy metals by AMH-3 was found to be governed by ion exchange rather than surface adsorption, and no significant change occurred in the structure of the AMH-3 during the ion exchange. The removal of various heavy metal ions (Pb 2+ , Cu 2+ , Cd 2+ , and Zn 2+ ) onto AMH-3 from aqueous solutions was conducted using a batch method. The effects of influential parameters, such as the initial metal ion concentration and contact time, on the sorption process were studied. The metal ion sorption capacity and removal efficiency were mainly dependent on the difference between the effective pore size of the AMH-3 and the hydrated radius of the metal ion. The sorption isotherm data were well fitted by Langmuir (for Pb 2+ , Cu 2+ , and Zn 2+ ) and Freundlich (for Cd 2+ ) models. The sorption kinetics data were well fitted by a pseudo-secondorder kinetic model. Competitive sorption experiments revealed an order of metal ion affinity of Pb 2+ > Cu 2+ > Zn 2+ > Cd 2+ . These findings indicate that AMH-3 is suitable for the efficient and selective removal of heavy metals from aqueous solutions.

This study focused on the influence of anion type on the depolymerization and its effect on the molecular state, dynamics and dispersity of cellulose. GPC and the van Gurp-Palmen plot showed that molar mass was more significantly decreased by 1-butyl-3-methylimidazolium chloride ([C4C1Im][Cl]) comparing to 1-butyl-3-methylimidazolium acetate ([C4C1Im][OAc]). Acid-catalyzed hydrolysis of cellulose in IL was proved using base titration which was monitored by conductivity and pH value. On the contrary to the depolymerization case, [C4C1Im][OAc] solution needed more base to be neutralized than [C4C1Im][Cl] solution. The generated carbene was combined with reducing ends of cellulose, which was facilitated in low molar mass consisting of a large number of reducing ends. The formation of cellulose-carbene substitution caused steric hindrance of cellulose chain, thus resulting in increased segmental friction with high molecular density. The cellulose particle combined with carbene can be dispersed stably in aqueous media.

An acid-recovering nanofiltration (NF) membrane with both acid resistance and selective acid permeability was fabricated via a water-based coating process for the recovery of hydrochloric acid. To achieve this, a thermally cross-linked branched-polyethyleneimine (b-PEI) layer was introduced to a loose polyethersulfone NF membrane by dip-coating of b-PEI and an epoxy linker and heat treatment in a sealed oven with a high-humidity atmosphere. The resulting membrane displayed a positive surface charge with a zeta potential, and exhibited a rejection performance order of MgCl2> MgSO4> NaCl > Na2SO4 characteristic of positive-charge-separation membranes. Mg rejection and Cl permeation experiments showed that the selective permeation of hydrochloric acid was achieved with Mg rejection above 95% and Cl permeation above 70%, and this allowed the acid to be recovered by obtaining permeate at the same pH as the feed. Moreover, the NF membrane maintained selective separation performance and flow rate for a month.

In this study, we designed novel methods to prepare a cellulose graft copolymer series (Cell-g-PDLs) with varied graft chain lengths, via direct ring-opening polymerization (ROP) of unmodified cellulose with alkyl-branched lactones. With increasing alkyl-branched graft chain length of the Cell-g-PDLs, the crystalline phase of cellulose became increasingly weakened, while the glass transition temperature significantly decreased. The latter was attributed to the extended free volume derived from the increased chain end-group concentrations of the branched graft chains. These results suggested that the incorporation of a highly alkyl-branched graft chain into unmodified cellulose is an effective way to improve its thermo-plasticity. Notably, the Cell-g-PDL with the longest graft chain (Cell-g-PDL9) was demonstrative of highly sufficient thermo-plasticity, owing to the enhanced molecular mobility resulting from the reduced frictional forces between the cellulose molecules.

We have developed magnetic core-hydrophilic shell nanospheres as a draw solute with enhanced stability for use in forward osmosis (FO) processes, which were prepared via a ligand exchange reaction. The combined results of TEM, DLS, FT-IR, and TGA analysis indicated that spherical magnetic nanospheres with 10 nm in diameter were successfully prepared via a thermal decomposition method. Hydrophilic shell layers were prepared using a ligand exchange reaction, and the hydrophilic siloxane agents were robustly bound to the surfaces of the magnetic nanosphere without inducing morphological changes. The number of hydrophilic agents presented in the magnetic nanospheres increased dramatically as a result of the covalently attached hydrophilic siloxane agents. The magnetic core-hydrophilic shell nanosphere draw solutes generated reasonable osmotic pressures due to their hydrophilic shell layer, rendering them useful for purifying mildly brackish water. As we intended, the osmotic pressure of the magnetic core-hydrophilic shell nanosphere was well maintained during repetitive magnetic recovery processes because the robustly bound the hydrophilic shell layer prevented particle aggregation.

The dynamic effects of unentangled star-shaped polymers with extremely small branches on the plasticization of miscible polymer blends are investigated using ultra-small branched star poly(e-caprolactone)s (USB-SPCLs), poly(vinyl chloride) (PVC), and their blends. Photon correlation dynamics of USB-SPCLs supports our previous suggestion that a whole USB-SPCL molecule acts as a single coarse-grain unit with dynamically-equivalent branches because of the extremely small branches, resulting in the total-molecular-weight-dependent Rouse dynamic behaviors of USB-SPCLs, regardless of the molecular architectures. The dynamic light scattering intensity autocorrelation curves of miscible PVC/USB-SPCL blends reveal that strong intermolecular interactions between PVC and USB-SPCL molecules determine the dynamic homogeneous behaviors of the blends despite their significantly different mobilities. The molecular motions of the blends depend on the total-molecular-weight-dependent Rouse dynamic behaviors of USB-SPCLs. These dynamic results clearly show the plasticization of the entangled neat linear PVC matrix by distinctive and rapid molecular mobility of USB-SPCLs.

The effect of the anion type, in an ionic liquid, on the transition of the crystalline structure when lignocellulose was pretreated in 1-ethyl-3-methylimidazolium acetate (EmimOAC) or 1-ethyl-3-methylimidazolium chloride (EmimCl) was studied. The influence of the pretreatment on the composition, the molecular structure, and the crystalline structure was observed using Fourier-transform infrared (FT-IR) compositional analysis, thermogravimetric analysis (TGA), rheological behavior, and X-ray diffraction (XRD). Compared to EmimCl, EmimOAC pretreatment substantially decreased the lignin and hemicellulose contents. The pretreatment also significantly changed the entanglement or crosslinking state of polymer chains in the lignocellulose solution. The changes in lignin content and the transformation from cellulose I to II were dependent on the anion type of the ionic liquid. The pretreated samples were recrystallized to cellulose II only in EmimOAC, whereas the samples pretreated with EmimCl had both cellulose I and II structures present at the same time.

We synthesize the anatase TiO 2 /zinc phthalocyanine (ZnPc) hybrids in various sizes (245–1188 nm) and examine the visible light photocatalytic activity of TiO 2 /ZnPc hybrids, in conjunction with their Mie light scattering ability. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy show that ZnPc molecules are well-incorporated and dispersed on the surface of the TiO 2 , instead of being aggregates. From the field-emission scanning electron microscopy, dynamic light scattering, and nitrogen adsorption–desorption analysis, we confirm the formation of spherical TiO 2 /ZnPc hybrids in various sizes (245, 548, 798, 1188 nm in diameter), the large specific surface areas (up to 223.76 m 2 /g), and the mesoporous structures. The mesoporous TiO 2 /ZnPc hybrids show excellent photocatalytic efficiency (up to 89.93% after 90 min) toward the degradation of methylene blue under visible light irradiation, which is about 2 times of that of simple nanoparticular P25/ZnPc. Among the mesoporous TiO 2 /ZnPc hybrids, the hybrid with a size of 548 nm (P123–TiO 2 /ZnPc) exhibits the highest photocatalytic activity. The highest activity observed on P123–TiO 2 /ZnPc may be attributed to its efficient cascade Mie scattering effect under visible light irradiation.

A selective adsorptive method using metal-organic frameworks (MOFs) was employed for removal of 3-MCPD and glycidol, which are potential genotoxic carcinogens. To optimize adsorption performance, a series of Fe-MIL-88 s with different ligand types were used with further modification by sequential carboxylation and deprotonation processes. Among these ligands, the MOFs, consisting of 2,6-naphthalenedicarboxylic acid (Fe-MIL-88_BDC) showed the best adsorption performance. A rapid efficiency improvement of 3-MCPD and glycidol was observed after its surface modification. Despite lacking superior porosity, deprotonated Fe-MIL-88_BDC showed the highest adsorption capacity of the reported adsorbents. We found that the remarkable improvement in adsorption efficiency was due to esterification with carboxyl groups on 3-MCPD and glycidol. This adsorption performance was seen only in 3-MCPD ester and glycidyl ester (as a precursor of 3-MCPD and glycidol) in palm oil without a change of fatty composition and minor components.

We developed a stimuli-responsive polyvinylidene fluoride (PVDF) microfiltration (MF) membrane with a photoreversible crosslinked layer. The photoreversible crosslinked layer on the membrane surface can be removed with the foulant layer through a UV process after the membrane is fouled, thereby restoring the degraded performance due to membrane fouling. To achieve this, we synthesized a photoresponsive linker by coupling cinnamic acid with epichlorohydrin and coated the photoresponsive crosslinked polyethylenimine layer onto a PVDF membrane with 0.1 μm pore size. The combined results of Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, ultraviolet–visible spectrophotometry, and field-emission scanning electron microscopy investigations clearly showed that the photoresponsive linker was successfully synthesized and that the photoresponsive layer (PRL) was coated onto the PVDF MF membrane via photoreversible crosslinking. The PRL-coated membrane exhibited hydrophilic surface properties in addition a high fouling resistance, and recovered the water flux >45% of the initial flux after backwashing in dead-end fouling tests with silica particles, whereas the neat membrane recovered the water flux only

We develop a plasticizer composed of alkyl terminal hyperbranched polyglycerol (alkyl-HPG) for the production of non-toxic, phthalate-free flexible poly(vinyl chloride) (PVC). The synthesized alkyl-HPGs are transparent liquids at room temperature and exhibit considerably lower volatility than di(2-ethylhexyl) phthalate (DEHP). The miscibility analyses reveal that the alkyl termination and the hyperbranched architecture of alkyl-HPG are the key factors for improving its miscibility with PVC, and butyl-terminated HPGs (HPG-C4s) are fairly miscible with PVC irrespective of their degree of polymerization (DP). The obtained PVC/HPG-C4 films exhibit similar flexibility and stretchability with the corresponding properties of PVC/DEHP films. In particular, PVC/HPG3-C4, the blend with the smallest DP, has excellent plasticization efficiency and low apparent activation energy (Ea) for α relaxation comparable to those of PVC/DEHP owing to its high concentration of chain ends. The transparency and thermal stability of PVC/HPG-C4 are rather better than those of PVC/DEHP, and HPG-C4s are biologically safe without acute toxicity. Moreover, PVC/HPG-C4 shows an extremely small degree of migration in leaching tests, more than 80% lower than that of PVC/DEHP.

The extremely small branched effects on molecular dynamics are investigated using well-defined star poly( e -caprolactone)s containing ultra-small branches (USB-SPCLs) as a model system. USB-SPCLs interestingly show total-molecular-weight-dependent glass transitions regardless of the molecular architecture parameters, such as the number and length of branches, whereas typical star polymers with polymeric large branches show the end-group-concentration-dependent glass transitions. The viscoelasticity of USB-SPCLs does not depend exponentially on the individual branched molecular weight, as observed in typical star polymers, and instead follows the modified Mark–Houwink power law and the Bueche-modified Rouse model for unentangled linear polymers. The flow activation energy and the longest Rouse relaxation time of USB-SPCLs show that the individual branches of USB-SPCL are dynamically equivalent and that a whole USB-SPCL molecule moves with a simple uni-motion. These results suggest that a whole USB-SPCL molecule presumably acts as a dynamically-equivalent single coarse-grain unit because of the extremely small branches on the scale of 20–40 atoms.

We develop a regenerable anti-fouling membrane via the formation of a dynamic peel-and-stick of hydrophilic poly(ethylene glycol) (PEG) layer onto the surface of a poly(tetrafluoroethylene) (PTFE) membrane, using thermo-responsive reversible covalent bonding. In order to attach a peelable-and-stickable hydrophlilic layer onto a membrane surface, a maleimide end-modified PEG layer is coupled with a furan-modified PTFE membrane by reversible Diels–Alder (DA) cycloaddition reaction. The combined results of attenuated total reflection Fourier-transform infrared (ATR FT-IR), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM) measurements clearly reveal that the maleimide end-modified PEG is successfully coupled with the furan-modified PTFE membrane surface by DA reaction. In addition, the hydrophilic PEG layer is readily and repeatedly reformed on the membrane surface by a thermally driven dynamic peel-and-stick process. The PEG-coupled PTFE membrane shows effective anti-fouling performance against a highly concentrated silica colloidal aqueous solution. In particular, the anti-fouling property is remarkably recovered after regeneration of the hydrophilic layer through the peel-and-stick process.

In this work, Ag–TiO2-embedded nanofiber composite (AT-in-NF) and Ag–TiO2-decorated nanofiber composite (AT-sur-NF) were comparatively studied to investigate the effect of the position of the silver-loaded titanium dioxide (Ag–TiO2) on the performance of nanofiber composites under visible light irradiation. AT-in-NF and AT-sur-NF were prepared by electrospinning and simultaneous electrospinning/electrospray process, respectively, and the compositions of the nanofiber composites were deliberately controlled to be the same with the exception of the Ag–TiO2 position. AT-sur-NF, in which the Ag–TiO2 was exposed on the nanofiber surface, showed better photo-induced self-cleaning behavior for methylene blue staining under visible light irradiation than AT-in-NF. AT-sur-NF also exhibited excellent bacterial growth inhibition for both Staphylococcus aureus (Gram-positive bacteria) and Klebsiella pneumoniae (Gram-negative bacteria) while AT-in-NF exhibited the bacterial growth inhibition for just K. pneumoniae. These results show that the presence of highly dispersed Ag–TiO2 on the nanofiber surface endows the nanofiber composite with superior photocatalytic and antimicrobial activities, and is useful for designing and optimizing the high performance nanofiber composites.

We develop an anti-scaling ultrafiltration/microfiltration (UF/MF) membrane by introducing a high-density positive charge to a poly(vinylidene fluoride) (PVDF) membrane to suppress membrane scaling in Ca2+/silica-rich wastewater. Positively charged modifiers are synthesized by conjugating an amphiphilic polymer (Brij S10) and branched poly(ethylene imine) (b-PEI) at various molar ratios, and these are then implanted to PVDF membranes during the phase-inversion process. Attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectra reveal that the positive modifiers successfully anchors onto the surface of the membrane by hydrophilic-hydrophobic phase recognition. As introducing the positive charge on the membrane surface, the membranes show positive surface charge and their pure water permeability (PWP) increases due to the protonation of b-PEI. Anti-scaling properties are also confirmed to be improved by filtration tests using a metal ions/silica-rich feed solution, which results from the repulsion of metal ion by the positively charged branch on the membrane. In addition, the water flux recovery by simple membrane backwashing of the modified membrane is double that of the neat PVDF membrane.

We successfully synthesize the three- and six-branched star poly(e-caprolactone)s with extremely small branched segments (USB-SPCLs) using a facile pseudo-one-pot process in a pilot scale and investigate the effect of ultra-small branches on their crystallization behaviors. The number of branched segments and the individual branched segment lengths for USB-SPCLs are precisely controlled via manipulating monomer-to-core ratio, adjusting monomer-to-polymer conversion, end-capping the terminal hydroxyl groups, and vacuum purification, which results in USB-SPCLs having the branched segments below five degree of polymerization with a high yield exceeding 93%. The molecular weights obtained from 1H NMR spectroscopy are consistent with that obtained from MALDI-TOF-MS and the molecular weight distributions are narrow with Mw/Mn ≤ 1.2, indicating that USB-SPCLs have mono-dispersed branches. USB-SPCLs have low melting temperatures and broad double-melting peaks attributed to their extremely small branches, and the crystallization behaviors for USB-SPCLs depend on the end group concentration. On the other hand, the glass transitions for USB-SPCLs depend on the total molecular weights, regardless of the number and length of branched segments. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1134–1142

Metal–organic frameworks (MOFs) have generated considerable interest as a potential candidate for hydrogen storage, owing to their extremely high surface-to-volume ratio and low density. However, practical applications have been limited because of low hydrogen storage capacity at room temperature, and of moisture sensitivity of MOFs. To improve hydrogen storage capacity at room temperature and hydrostability under ambient conditions, platinum (Pt) nanoparticles were introduced on the outer surface of MOF-5, Zn 4 O(1,4-benzenedicarboxylate) 3 that was then coated with hydrophobic microporous carbon black (CB) to generate a CB/Pt/MOF-5 composite. To study the chemical composition, morphology, crystallinity, and properties of the synthesized material, various techniques were employed including wide-angle X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectrometry, high-resolution transmission electron microscopy, and N 2 adsorption–desorption analysis. The characterization analyses confirmed the formation of a novel composite designated as CB/Pt/MOF-5 with a highly crystalline structure, and large specific surface area and pore volume. The hydrogen storage capacity (0.62 wt.%) of CB/Pt/MOF-5 was superior to that of pristine MOF-5 (0.44 wt.%) by 41%; furthermore, CB/Pt/MOF-5 displayed excellent hydrostability under ambient conditions. Overall, these findings indicate that MOF-5 with improved hydrogen storage capacity and hydrostability was successfully synthesized by introducing Pt nanoparticles and a carbon black layer.

Herein, we describe the preparation of flexible poly(vinyl chloride) (PVC) containing hyperbranched polyglycerol (HPG)-functionalized graphene oxide (HGO) as a reinforcing filler and reveal that the obtained composites exhibit greatly improved gas barrier properties. Moreover, we show that HGO, synthesized by surface-initiated ring-opening polymerization of glycidol followed by esterification with butyric anhydride, exists as individual exfoliated nanosheets possessing abundant functional groups capable of interacting with PVC. A comparative study of butyl-terminated graphene oxide (BGO) reveals that functionalization with HPG is of key importance for achieving a uniform dispersion of HGO in the PVC matrix and results in strong interfacial interactions between HGO and PVC. As a result, flexible PVC/HGO nanocomposite films exhibit significantly enhanced tensile strength and toughness compared to those of neat plasticized PVC while maintaining its inherent stretchability. Furthermore, the two-dimensional planar structure and homogeneous distribution of HGO in PVC/HGO nanocomposites make gas molecules follow a highly tortuous path, resulting in remarkably reduced oxygen permeability, which is more than 60% lower than that of neat plasticized PVC. Consequently, HGO is demonstrated to be promising component of flexible and gas-impermeable PVC films for a wide range of applications.

We develop mesoporous magnetic clusters (MMCs) functionalized with hydrophilic branched polyethylenimine (b-PEI), later called b-MG, and MMCs functionalized with positively charged b-PEI (p-MG). These materials efficiently remove Pb(II) and Cr(VI) from wastewater. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and nitrogen adsorption-desorption analysis results clearly indicate that hydrophilic b-PEI and positively charged b-PEI are successfully attached to the MMC surfaces. Wide-angle X-ray diffraction, high-resolution transmission electron microscopy, and field-emission scanning electron microscopy analyses confirm that the crystal structures and morphologies of the MMCs are maintained well even when wet chemical modification processes are used to introduce hydrophilic b-PEI and positively charged b-PEI to the MMC surfaces. Langmuir and Sips isotherm models are applied to describe Pb(II) adsorption behavior of the b-MG and Cr(VI) adsorption behavior of the p-MG. The isotherm models indicate that the maximum adsorption capacities of b-MG and p-MG, respectively, are 216.3 and 334.1 mg g-1, respectively. These are higher than have previously been found for other adsorbents. In reusability tests, using magnetic separation and controlling the pH, the Pb(II) recovery efficiency of the b-MG is 95.6% and the Cr(VI) recovery efficiency of the p-MG is 68.0% even after the third cycle.

We demonstrate here the fabrication of a novel morphology of bowl-shaped TiO2 aggregates via a facile electrospray technique using TiO2 nanowires. These have been prepared by using lauric acid via solvothermal synthetic route. The modulation of surface energies of the different crystallographic faces through the use of lauric acid is the key parameter for the anisotropic growth. These aggregates have high specific surface area of up to 93.10 m2/g, and relatively large pores with a mean size of 4.68 nm. These porous structures can provide a high number of active adsorption sites and act as photo-related reaction centers. The prepared bowl-shaped TiO2 are in micrometer size and have good morphology and high specific surface area. A possible mechanism for the formation of bowl-shaped TiO2 aggregates is also proposed, based on the results. The light scattering properties of bowl-shaped architectures are characterized by the UV–Vis spectrometry. The superior light scattering abilities of bowl-shape makes them promising architectures for applications in the photovoltaic devices.

Phthalocyanine (Pc) derivatives and hyperbranched poly(amidoamine) (HPAMAM) were synthesized and then modified with maleimide groups. They were then coupled to a poly(tetrafluoroethylene) (PTFE) membrane modified with furan groups through a Diels-Alder (DA) reaction. In this multi-functional PTFE membrane, Pc fluorescence was quenched by heavy-metal-ions, while HPAMAM adsorbed them to prevent leakage. In addition, HPAMAM hydrophilicity improved water permeability through the membrane. Thermally reversible DA bonding between furan and maleimide groups also allows selective regeneration and replacement of the functional materials on the membrane. Modification and functionality of the membrane were characterized with Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, fluorescence spectroscopy, and inductively coupled plasma atomic emission spectroscopy. The analyses revealed a renewable, multi-functional membrane that detected and eliminated heavy metal ions.

We describe here the preparation of hyperbranched poly(amidoamine)-grafted poly(tetrafluoroethylene) microfiltration membranes, and demonstrate their potential applicability to water treatment and heavy metals removal. The membranes were fabricated by surface amination of PTFE membranes with hydrazine, followed by chemical coupling with the hydrophilic chelating agent hyperbranched poly(amidoamine) (HPAMAM). Membrane structures were evaluated by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and contact angle measurements. The amount of grafted HPAMAM was quantitated by the acid dye adsorption/desorption method. Coupling of HPAMAM to PTFE membranes greatly enhanced water flux without negatively affecting their rejection property as well as increasing its ability to remove heavy metal ions. At an operating pressure of 25 kPa, the pure water flux of PTFE membrane was nearly 0 L/m2 h, whereas the flux of HPAMAM-grafted PTFE membranes was 635±9 L/m2 h. In addition, HPAMAM-grafted PTFE membranes adsorbed 1.42 g/m2 Cu2+ ions from aqueous solution, with up to 90% desorption under acidic conditions and highly preserved adsorption capacity for Cu2+ ions with re-using cycles. These results indicate HPAMAM-grafted PTFE microfiltration membranes can be highly efficient and reusable for the removal of toxic heavy metal ions and these microfiltration membranes can be useful in water treatment technology.