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2018 Volume 36 Issue 1
2018, 36(1):
Abstract:
2018, 36(1): 1-7
doi: 10.1007/s10118-018-2010-5
Abstract:
A novel scale-up ambient pressure synthetic strategy for the preparation of imine-based covalent organic frameworks (COFs) was proposed through dynamic imine exchange reaction mechanism. The obtained COFs exhibited good crystallinity and much higher porosity comparable to their solvothermally synthesized counterparts. Moreover, under ambient pressure, the COF nanofibers could readily grow on the surface of polyimide films, and the resulted nanocomposite film showed an interesting colorimetric acid-responsive behavior.
A novel scale-up ambient pressure synthetic strategy for the preparation of imine-based covalent organic frameworks (COFs) was proposed through dynamic imine exchange reaction mechanism. The obtained COFs exhibited good crystallinity and much higher porosity comparable to their solvothermally synthesized counterparts. Moreover, under ambient pressure, the COF nanofibers could readily grow on the surface of polyimide films, and the resulted nanocomposite film showed an interesting colorimetric acid-responsive behavior.
2018, 36(1): 8-17
doi: 10.1007/s10118-018-2061-7
Abstract:
Hydrogels are a kind of unique cross-linking polymeric materials with three-dimensional networks. Various efforts have been devoted to manipulate the formation of functional hydrogels in situ and enrich the production of hydrogels, microgels and nanogels with improved modulation capacity. However, these methods always fail to tune the gel properties because of the difficulty in achieving the precise control of cross-linking extents once the gel formation is initiated. Therefore, the preparation of tailor-made hydrogels remains a great challenge. Herein, we summarize a controlled cross-linking strategy towards not only fabrication of hydrogels at nano-, micro-and macro-scales, but also achievement of controlled assembly of nanoparticles into multifunctional materials in macroscopic and microscopic scales. The strategy is conducted by controllably activating and terminating the disulfide reshuffling reactions of disulfide-linked core/shell materials with selective core/shell separation using system pH or UV triggers. So it provides a facile approach to producing hydrogels, hydrogel particles and nanoparticle aggregates with tunable structures and properties, opening up the design possibility, flexibility and complexity of hydrogels, microgels/nanogels and nanoparticle aggregates from nanoscopic components to macroscopic objects.
Hydrogels are a kind of unique cross-linking polymeric materials with three-dimensional networks. Various efforts have been devoted to manipulate the formation of functional hydrogels in situ and enrich the production of hydrogels, microgels and nanogels with improved modulation capacity. However, these methods always fail to tune the gel properties because of the difficulty in achieving the precise control of cross-linking extents once the gel formation is initiated. Therefore, the preparation of tailor-made hydrogels remains a great challenge. Herein, we summarize a controlled cross-linking strategy towards not only fabrication of hydrogels at nano-, micro-and macro-scales, but also achievement of controlled assembly of nanoparticles into multifunctional materials in macroscopic and microscopic scales. The strategy is conducted by controllably activating and terminating the disulfide reshuffling reactions of disulfide-linked core/shell materials with selective core/shell separation using system pH or UV triggers. So it provides a facile approach to producing hydrogels, hydrogel particles and nanoparticle aggregates with tunable structures and properties, opening up the design possibility, flexibility and complexity of hydrogels, microgels/nanogels and nanoparticle aggregates from nanoscopic components to macroscopic objects.
2018, 36(1): 18-24
doi: 10.1007/s10118-018-2008-z
Abstract:
A series of triblock copolymers, containing a CO2-switchable block poly(2-(dimethylamino)ethyl methacrylate) (PDM) block and two symmetrical hydrophilic blocks polyacrylamide (PAM), were synthesized using atom transfer radical polymerization (ATRP) method. The pH and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO2, and the triblock copolymer aqueous solution displayed a CO2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar vesicle-network aggregate structure transition. The release of rhodamine B from the vesicles with and without CO2 stimuli showed the potential application in drug delivery domains; after CO2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO2-switchable morphology changes and CO2-induced drug release was proposed.
A series of triblock copolymers, containing a CO2-switchable block poly(2-(dimethylamino)ethyl methacrylate) (PDM) block and two symmetrical hydrophilic blocks polyacrylamide (PAM), were synthesized using atom transfer radical polymerization (ATRP) method. The pH and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO2, and the triblock copolymer aqueous solution displayed a CO2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar vesicle-network aggregate structure transition. The release of rhodamine B from the vesicles with and without CO2 stimuli showed the potential application in drug delivery domains; after CO2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO2-switchable morphology changes and CO2-induced drug release was proposed.
2018, 36(1): 25-33
doi: 10.1007/s10118-018-2006-1
Abstract:
Polyelectrolyte-surfactant complexes (PESCs) were fabricated through the interaction of poly(acrylic acid) and four different cationic surfactants or their mixtures. PESC membranes were prepared by solution casting method and were applied in ethanol recovery from aqueous solution via pervaporation. Elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), water contact angle (CA) measurement, differential scanning calorimetry (DSC) and X-ray scattering were employed to characterize the composition, structure and properties of PESCs. The results reveal that the investigated PESCs are similar in hydrophobicity but different in hierarchical nanostructures. In separating 5 wt% ethanol/water mixture, PESC membranes with high crystallinity will have both low flux and ethanol selectivity because of the high packing density and low permeability of crystalline regions. Meanwhile, the hierarchical nanostructures of PESC membranes change under pervaporation environment as was revealed by in situ synchrotron radiation X-ray scattering measurement. That is, the crystalline region could melt at high temperature in swelling state, thus consequently enhancing the ethanol selectivity.
Polyelectrolyte-surfactant complexes (PESCs) were fabricated through the interaction of poly(acrylic acid) and four different cationic surfactants or their mixtures. PESC membranes were prepared by solution casting method and were applied in ethanol recovery from aqueous solution via pervaporation. Elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), water contact angle (CA) measurement, differential scanning calorimetry (DSC) and X-ray scattering were employed to characterize the composition, structure and properties of PESCs. The results reveal that the investigated PESCs are similar in hydrophobicity but different in hierarchical nanostructures. In separating 5 wt% ethanol/water mixture, PESC membranes with high crystallinity will have both low flux and ethanol selectivity because of the high packing density and low permeability of crystalline regions. Meanwhile, the hierarchical nanostructures of PESC membranes change under pervaporation environment as was revealed by in situ synchrotron radiation X-ray scattering measurement. That is, the crystalline region could melt at high temperature in swelling state, thus consequently enhancing the ethanol selectivity.
2018, 36(1): 34-42
doi: 10.1007/s10118-018-2005-2
Abstract:
Ordered porous block copolymer films (PBCFs) have attracted much attention because of their potential applications in several fields. In this paper, we first reported a non-destructive, controllable, and efficient approach for preparation of β-cyclodextrin (β-CD)-functionalized PBCFs (β-CD-PBCFs). The key point of the approach is to incorporate β-CD units into the hydrophilic segment of amphiphilic block copolymers before the preparation of films. β-CD-PBCFs with structural integrity and controllable pore parameters were fabricated through combining of self-assembly and breath figure methods. And then, the effective adsorption capacity of β-CD-PBCFs toward Congo red was confirmed through UV-Vis spectroscopy and was found to be affected by β-CD content and solution pH values. Adsorption kinetic results showed that the adsorption behavior of β-CD-PBCFs was consistent with the pseudo-second-order kinetic model and the chemisorption mechanism.
Ordered porous block copolymer films (PBCFs) have attracted much attention because of their potential applications in several fields. In this paper, we first reported a non-destructive, controllable, and efficient approach for preparation of β-cyclodextrin (β-CD)-functionalized PBCFs (β-CD-PBCFs). The key point of the approach is to incorporate β-CD units into the hydrophilic segment of amphiphilic block copolymers before the preparation of films. β-CD-PBCFs with structural integrity and controllable pore parameters were fabricated through combining of self-assembly and breath figure methods. And then, the effective adsorption capacity of β-CD-PBCFs toward Congo red was confirmed through UV-Vis spectroscopy and was found to be affected by β-CD content and solution pH values. Adsorption kinetic results showed that the adsorption behavior of β-CD-PBCFs was consistent with the pseudo-second-order kinetic model and the chemisorption mechanism.
2018, 36(1): 43-48
doi: 10.1007/s10118-018-2012-3
Abstract:
Polymer hollow microspheres were prepared by performing alkali treatment on the multilayer core/shell polymer latex particles containing carboxyl groups. Effects of the shell composition and dosage as well as alkali type on the morphology of the microspheres were investigated. Results showed that in comparison with acrylonitrile (AN) and methacrylic acid (MAA), using butyl acrylate (BA) as the shell co-monomer decreased the glass transition temperature (Tg) of shell effectively and was beneficial to the formation of uniform and big hollow structure. Along with the increase of the shell dosage, the alkali-treated microspheres sequentially presented porous and hollow morphology, and the size of microspheres increased, while the hollow diameter increased first and then decreased, and the maximum hollow ratio reached 39.5%. Furthermore, the multilayer core/shell microspheres had better tolerance to NH3·H2O than to NaOH. When the molar ratio of alkali to methacrylic acid (MRalkali/acid) for NaOH ranged from 1.15 to 1.30 or MRalkali/acid for NH3·H2O ranged from 1.30 to 2.00, the regular polymer hollow microspheres could be obtained.
Polymer hollow microspheres were prepared by performing alkali treatment on the multilayer core/shell polymer latex particles containing carboxyl groups. Effects of the shell composition and dosage as well as alkali type on the morphology of the microspheres were investigated. Results showed that in comparison with acrylonitrile (AN) and methacrylic acid (MAA), using butyl acrylate (BA) as the shell co-monomer decreased the glass transition temperature (Tg) of shell effectively and was beneficial to the formation of uniform and big hollow structure. Along with the increase of the shell dosage, the alkali-treated microspheres sequentially presented porous and hollow morphology, and the size of microspheres increased, while the hollow diameter increased first and then decreased, and the maximum hollow ratio reached 39.5%. Furthermore, the multilayer core/shell microspheres had better tolerance to NH3·H2O than to NaOH. When the molar ratio of alkali to methacrylic acid (MRalkali/acid) for NaOH ranged from 1.15 to 1.30 or MRalkali/acid for NH3·H2O ranged from 1.30 to 2.00, the regular polymer hollow microspheres could be obtained.
2018, 36(1): 49-57
doi: 10.1007/s10118-018-2004-3
Abstract:
Modified clay/polyethersulfone (PES) mixed matrix membranes (MMMs) were prepared by acid activated montmorillonite (AA-MMT) with different concentrations and used to eliminate dyes and remove heavy metals from aqueous solution. The morphology and physiochemical properties of prepared clay nanoparticles and MMMs were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), enegy dispersive X-ray (EDX) spectroscopy, Brunauer-Emmett-Teller (BET) analysis, atomic force microscopy (AFM), contact angle measurement and fouling studies. The filtration study showed that removal of dyes and heavy metals was strongly dependent on pH so that dyes with positive and negative charges showed different separation efficiency in acidic and alkaline conditions. The modified membranes possessed better heavy metal removal in acidic and alkaline pHs. When the rejection of heavy metals was measured in an alkaline environment, it was observed that the rejection had a great increase compared to the neutral values for Zn2+ and Ni2+ ions, while rejection of Cu2+ and Cd2+ did not undergo significant changes. So it can be concluded that modified membranes show good selectivity for elimination of Zn2+ and Ni2+ ions with respect to other cations.
Modified clay/polyethersulfone (PES) mixed matrix membranes (MMMs) were prepared by acid activated montmorillonite (AA-MMT) with different concentrations and used to eliminate dyes and remove heavy metals from aqueous solution. The morphology and physiochemical properties of prepared clay nanoparticles and MMMs were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), enegy dispersive X-ray (EDX) spectroscopy, Brunauer-Emmett-Teller (BET) analysis, atomic force microscopy (AFM), contact angle measurement and fouling studies. The filtration study showed that removal of dyes and heavy metals was strongly dependent on pH so that dyes with positive and negative charges showed different separation efficiency in acidic and alkaline conditions. The modified membranes possessed better heavy metal removal in acidic and alkaline pHs. When the rejection of heavy metals was measured in an alkaline environment, it was observed that the rejection had a great increase compared to the neutral values for Zn2+ and Ni2+ ions, while rejection of Cu2+ and Cd2+ did not undergo significant changes. So it can be concluded that modified membranes show good selectivity for elimination of Zn2+ and Ni2+ ions with respect to other cations.
2018, 36(1): 58-64
doi: 10.1007/s10118-018-2011-4
Abstract:
Tens of billion metric tons of anthropogenic CO2 discharged from the burning of fossil fuels lead to an enormous environmental and resource burden. It is charming to transform CO2 to desirable, economical chemicals and materials. Poly(propylene carbonate) (PPC) is an emerging CO2-based material. Herein, we report the design, synthesis and characterization of the reactive hot melt polyurethane adhesive (RHMPA) based on PPC polyol. The resultant RHMPAs exhibit good adhesion properties to multiple substrates including plastics (PC, PMMA, ABS) and metals (aluminium, steel), which is comparable to or even better than conventional RHMPAs prepared from petro-based polyol. Furthermore, the PPC-based RHMPAs have tunable mechanical properties, and are thermally stable in the typical working range of bonding process (up to 270℃). The study is expected to expand the applications of PPC and provide a new type of CO2-based renewable and eco-friendly materials.
Tens of billion metric tons of anthropogenic CO2 discharged from the burning of fossil fuels lead to an enormous environmental and resource burden. It is charming to transform CO2 to desirable, economical chemicals and materials. Poly(propylene carbonate) (PPC) is an emerging CO2-based material. Herein, we report the design, synthesis and characterization of the reactive hot melt polyurethane adhesive (RHMPA) based on PPC polyol. The resultant RHMPAs exhibit good adhesion properties to multiple substrates including plastics (PC, PMMA, ABS) and metals (aluminium, steel), which is comparable to or even better than conventional RHMPAs prepared from petro-based polyol. Furthermore, the PPC-based RHMPAs have tunable mechanical properties, and are thermally stable in the typical working range of bonding process (up to 270℃). The study is expected to expand the applications of PPC and provide a new type of CO2-based renewable and eco-friendly materials.
2018, 36(1): 65-77
doi: 10.1007/s10118-018-2021-2
Abstract:
In this work, polysulfone/polyimide (PSf/PI) mixed matrix membranes were fabricated by reinforcement of modified zeolite (MZ) particles through solution casting method for investigation of antibacterial activity against two gram negative bacteria (Salmonella typhi, Klebsella pneumonia) and two gram positive bacteria (Staphylococcus aureus, Bacillus subtilis). The modified zeolite particles were incorporated to PSf and PI matrix and the influence of these particles on thermal, mechanical and structural properties was evaluated. The morphological evolution was investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis, which revealed good compatibility between organic polymer matrix and inorganic filler. Mechanical stability was investigated by tensile testing while thermal analysis was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). This revealed improvement in thermal properties with increasing filler concentration from 1 wt% to 10 wt%. Structural analysis was successfully done using X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. Solvent content of fabricated mixed matrix membranes was observed to decrease while moving from more hydrophilic to less hydrophilic solvent. However, addition of filler content enhanced the porosity of fabricated membranes. The synthesized mixed matrix membranes exhibited good antibacterial activity and the highest activity was shown by PSf/PI/MZ mixed matrix membrane. Therefore, the combination effect of PSf, PI and MZ sufficiently enhanced the antibacterial activity of mixed matrix membranes.
In this work, polysulfone/polyimide (PSf/PI) mixed matrix membranes were fabricated by reinforcement of modified zeolite (MZ) particles through solution casting method for investigation of antibacterial activity against two gram negative bacteria (Salmonella typhi, Klebsella pneumonia) and two gram positive bacteria (Staphylococcus aureus, Bacillus subtilis). The modified zeolite particles were incorporated to PSf and PI matrix and the influence of these particles on thermal, mechanical and structural properties was evaluated. The morphological evolution was investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis, which revealed good compatibility between organic polymer matrix and inorganic filler. Mechanical stability was investigated by tensile testing while thermal analysis was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). This revealed improvement in thermal properties with increasing filler concentration from 1 wt% to 10 wt%. Structural analysis was successfully done using X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. Solvent content of fabricated mixed matrix membranes was observed to decrease while moving from more hydrophilic to less hydrophilic solvent. However, addition of filler content enhanced the porosity of fabricated membranes. The synthesized mixed matrix membranes exhibited good antibacterial activity and the highest activity was shown by PSf/PI/MZ mixed matrix membrane. Therefore, the combination effect of PSf, PI and MZ sufficiently enhanced the antibacterial activity of mixed matrix membranes.
2018, 36(1): 78-84
doi: 10.1007/s10118-018-2016-z
Abstract:
The ionic conductivity and the mechanical strength are two key factors for the performance of poly(ethylene oxide) (PEO) based polyelectrolytes. However, crystallized PEO suppresses ion conductivity at low temperature and melted PEO has low mechanical strength at high temperature. Here, random binary brush copolymer composed of PEO- and polystyrene (PS)-based side chains is synthesized. PEO crystallinity is suppressed by the introduction of PS brushes. Doping with lithium trifluoromethanesulfonate (LiTf) induces microphase separation. Due to a random arrangement of the brushes, the microphase segregation is incomplete even at high salt loading, which provides both high ionic conductivity and high mechanical strength at room temperature. These results provide opportunities for the design of polymeric electrolytes to be used at room temperature.
The ionic conductivity and the mechanical strength are two key factors for the performance of poly(ethylene oxide) (PEO) based polyelectrolytes. However, crystallized PEO suppresses ion conductivity at low temperature and melted PEO has low mechanical strength at high temperature. Here, random binary brush copolymer composed of PEO- and polystyrene (PS)-based side chains is synthesized. PEO crystallinity is suppressed by the introduction of PS brushes. Doping with lithium trifluoromethanesulfonate (LiTf) induces microphase separation. Due to a random arrangement of the brushes, the microphase segregation is incomplete even at high salt loading, which provides both high ionic conductivity and high mechanical strength at room temperature. These results provide opportunities for the design of polymeric electrolytes to be used at room temperature.
2018, 36(1): 85-97
doi: 10.1007/s10118-018-2014-1
Abstract:
In this study, two fluorinated polyurethanes (FPU) containing carborane groups in the main chains were firstly designed and synthesized via the reaction of hexamethylene diisocyanate trimer (HDI trimer) with fluorinated polyesters (CFPETs) having hydroxyl-terminated carborane groups at room temperature. The structures of carborane fluorinated polyesters (CFPETs) and polyurethanes (CFPUs) were characterized by gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) measurements. The thermal stability, mechanical properties, Shore A hardness, solvent resistance and acid-alkali resistance of the carborane fluorinated polyurethane films were also studied. Thermogravimetric analysis (TGA) tests manifested that the introduction of carborane groups into the main chain of fluorinated polyurethane endowed the obtained fluorinated polyurethane with excellent thermal stability. The thermal decomposition temperature of carborane fluorinated polyurethane (CFPU) increased by 190℃ compared with that of the carborane-free fluorinated polyurethane (FPU). Even at 800℃, CFPU showed the char yield of 66.5%, which was higher than that of FPU (34.3%). The carborane-containing fluorinated polyurethanes also showed excellent chemical resistance and prominent mechanical property even after the cured films being immersed into Jet aircraft oil or 37% HCl for 168 h or at high temperature (700℃). It is found that the structural characteristics of carborane group and the compacted structure of CFPU effectively improve the thermal stability, mechanical property, solvent resistance and acid-alkali resistance of the carborane-free fluorinated polyurethane. These excellent properties make CFPU as the useful raw materials to prepare the high temperature resistant coatings or adhesives for automotive engines, engine or fuel tank of aircraft and other equipment working in high-temperature or high concentrations of acid-alkali environments.
In this study, two fluorinated polyurethanes (FPU) containing carborane groups in the main chains were firstly designed and synthesized via the reaction of hexamethylene diisocyanate trimer (HDI trimer) with fluorinated polyesters (CFPETs) having hydroxyl-terminated carborane groups at room temperature. The structures of carborane fluorinated polyesters (CFPETs) and polyurethanes (CFPUs) were characterized by gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) measurements. The thermal stability, mechanical properties, Shore A hardness, solvent resistance and acid-alkali resistance of the carborane fluorinated polyurethane films were also studied. Thermogravimetric analysis (TGA) tests manifested that the introduction of carborane groups into the main chain of fluorinated polyurethane endowed the obtained fluorinated polyurethane with excellent thermal stability. The thermal decomposition temperature of carborane fluorinated polyurethane (CFPU) increased by 190℃ compared with that of the carborane-free fluorinated polyurethane (FPU). Even at 800℃, CFPU showed the char yield of 66.5%, which was higher than that of FPU (34.3%). The carborane-containing fluorinated polyurethanes also showed excellent chemical resistance and prominent mechanical property even after the cured films being immersed into Jet aircraft oil or 37% HCl for 168 h or at high temperature (700℃). It is found that the structural characteristics of carborane group and the compacted structure of CFPU effectively improve the thermal stability, mechanical property, solvent resistance and acid-alkali resistance of the carborane-free fluorinated polyurethane. These excellent properties make CFPU as the useful raw materials to prepare the high temperature resistant coatings or adhesives for automotive engines, engine or fuel tank of aircraft and other equipment working in high-temperature or high concentrations of acid-alkali environments.
2018, 36(1): 98-105
doi: 10.1007/s10118-018-2007-0
Abstract:
We report a synthesis of microporous organic nanotube networks (MONNs) by a combination of hyper cross-linking and molecular templating of core-shell bottlebrush copolymers. The intrabrush and interbrush cross-linking of polystyrene (PS) shell layer in the core-shell bottlebrush copolymers led to the formation of micropores and large-sized nanopores (meso/macrospores) in MONNs, respectively, while selective removal of polylactide (PLA) core layer generated mesoporous tubular structure. The size of PLA-templated mesoporous cores and porous structure both at micro-and meso-scale could be controlled by simple tuning of the ratio of core/shell or the PLA core fraction in the bottlebrush precursors. Moreover, the resultant MONNs showed a highly selective adsorption capacity for the positively charged dyes on the basis of multi-porosity and carboxylate group-rich structure. In addition, MONNs also exhibited effective performance in size-selective adsorption of biomacromolecules. This work represents a new avenue for the preparation of MONNs and also provides a new application for molecular bottlebrushes in nanotechnology.
We report a synthesis of microporous organic nanotube networks (MONNs) by a combination of hyper cross-linking and molecular templating of core-shell bottlebrush copolymers. The intrabrush and interbrush cross-linking of polystyrene (PS) shell layer in the core-shell bottlebrush copolymers led to the formation of micropores and large-sized nanopores (meso/macrospores) in MONNs, respectively, while selective removal of polylactide (PLA) core layer generated mesoporous tubular structure. The size of PLA-templated mesoporous cores and porous structure both at micro-and meso-scale could be controlled by simple tuning of the ratio of core/shell or the PLA core fraction in the bottlebrush precursors. Moreover, the resultant MONNs showed a highly selective adsorption capacity for the positively charged dyes on the basis of multi-porosity and carboxylate group-rich structure. In addition, MONNs also exhibited effective performance in size-selective adsorption of biomacromolecules. This work represents a new avenue for the preparation of MONNs and also provides a new application for molecular bottlebrushes in nanotechnology.
2018, 36(1): 106-112
doi: 10.1007/s10118-018-2033-y
Abstract:
High performance resin must be used in the high performance glass fiber-reinforced plastic (GFRP) composites, but it is sometimes difficult to balance the processabilities and the final properties in the design of advanced thermoset GFRP composites. In this study, a phthalonitrile/benzoxazine (PPN/BZ) blend with excellent processability has been designed and applied in the GFRP composite materials. PPN/BZ blend with good solubility, low melt viscosity, appropriate gel condition and low-temperature curing behavior could enable their GFRP composite preparation with the prepreg-laminate method under a relatively mild condition. The resulted PPN/BZ GFRP composites exhibit excellent mechanical properties with flexural strength over 700 MPa and flexural modulus more than 19 GPa. Fracture surface morphologies of the PPN/BZ GFRP composites show that the interfacial adhesion between resin and GF is improved. The temperatures at weight loss 5% (T5%) and char residue at 800℃ of all PPN/BZ GFRP composites are over 435℃ and 65% respectively. PPN/BZ GFRP composites with high performance characteristics may find applications under some critical circumstances with requirements of high mechanical properties and high service temperatures.
High performance resin must be used in the high performance glass fiber-reinforced plastic (GFRP) composites, but it is sometimes difficult to balance the processabilities and the final properties in the design of advanced thermoset GFRP composites. In this study, a phthalonitrile/benzoxazine (PPN/BZ) blend with excellent processability has been designed and applied in the GFRP composite materials. PPN/BZ blend with good solubility, low melt viscosity, appropriate gel condition and low-temperature curing behavior could enable their GFRP composite preparation with the prepreg-laminate method under a relatively mild condition. The resulted PPN/BZ GFRP composites exhibit excellent mechanical properties with flexural strength over 700 MPa and flexural modulus more than 19 GPa. Fracture surface morphologies of the PPN/BZ GFRP composites show that the interfacial adhesion between resin and GF is improved. The temperatures at weight loss 5% (T5%) and char residue at 800℃ of all PPN/BZ GFRP composites are over 435℃ and 65% respectively. PPN/BZ GFRP composites with high performance characteristics may find applications under some critical circumstances with requirements of high mechanical properties and high service temperatures.
2018, 36(1): 113-118
doi: 10.1007/s10118-018-2018-x
Abstract:
The polypropylene/glass fiber (PP/GF) composites with excellent antistatic performance and improved mechanical properties have been reported by incorporation of a very small amount of the organic salt, lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI), into the PP/GF composites. It was considered that GF could play the role as the pathways for the movements of ions in the ternary composites. In this work, the interactions between Li-TFSI and glass fiber and the effects of such interactions on the physical properties of the composites have been systematically investigated. Three types of glass fibers with different-OH group concentrations have been prepared in order to compare the interactions between GF and Li-TFSI. It was found that the-OH group concentrations on the surface of glass fiber have significant effects on interactions between glass fibers and Li-TFSI. Such interactions are crucial for both the antistatic and mechanical performances of the final PP/GF/Li-TFSI composites. The investigation indicated that the GF with high-OH group concentrations confined the movement of TFSI-, which decreased the antistatic properties of PP/GF/Li-TFSI composites. On the other hand, the GF with low-OH group concentrations inhibited the absorption of Li-TFSI onto the GF, which also hindered the formation of Li-TFSI conductive pathway. The best antistatic performance of the ternary composites can be achieved at the intermediate-OH concentrations on the GF.
The polypropylene/glass fiber (PP/GF) composites with excellent antistatic performance and improved mechanical properties have been reported by incorporation of a very small amount of the organic salt, lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI), into the PP/GF composites. It was considered that GF could play the role as the pathways for the movements of ions in the ternary composites. In this work, the interactions between Li-TFSI and glass fiber and the effects of such interactions on the physical properties of the composites have been systematically investigated. Three types of glass fibers with different-OH group concentrations have been prepared in order to compare the interactions between GF and Li-TFSI. It was found that the-OH group concentrations on the surface of glass fiber have significant effects on interactions between glass fibers and Li-TFSI. Such interactions are crucial for both the antistatic and mechanical performances of the final PP/GF/Li-TFSI composites. The investigation indicated that the GF with high-OH group concentrations confined the movement of TFSI-, which decreased the antistatic properties of PP/GF/Li-TFSI composites. On the other hand, the GF with low-OH group concentrations inhibited the absorption of Li-TFSI onto the GF, which also hindered the formation of Li-TFSI conductive pathway. The best antistatic performance of the ternary composites can be achieved at the intermediate-OH concentrations on the GF.
2018, 36(1): 119-128
doi: 10.1007/s10118-018-2015-0
Abstract:
In this work, the effect of the fullerene (C60) weight fraction and PB-C60 interaction on the glass transition temperature (Tg) of polymer chains has been systemically investigated by adopting the united atom model of cis-1, 4-poly(butadiene) (cis-PB). Various chain dynamics properties, such as atom translational mobility, bond/segment reorientation dynamics, torsional dynamics, conformational transition rate and dynamic heterogeneity of the cis-PB chains, are analyzed in detail. It is found that Tg could be affected by the C60 weight fraction due to its inhibition effect on the mobility of the cis-PB chains. However, Tg is different, which depends on different dynamics scales. Among the chain dynamics properties, Tg is the lowest from atom translational mobility, while it is the highest from the dynamic heterogeneity. In addition, Tg can be more clearly distinguished from the dynamic heterogeneity; however, the conformational transition rate seems to be not very sensitive to the C60 weight fraction compared with others. For pure cis-PB chains, Tg and the activation energy in this work can be compared with those of other polymers. In addition, the temperature dependence of the dynamic properties has different Arrhenius behaviors above and below Tg. The activation energy below Tg is lower than that above Tg. This work can help to understand the effect of the C60 on the dynamic properties and glass transition temperature of the cis-PB chains from different scales.
In this work, the effect of the fullerene (C60) weight fraction and PB-C60 interaction on the glass transition temperature (Tg) of polymer chains has been systemically investigated by adopting the united atom model of cis-1, 4-poly(butadiene) (cis-PB). Various chain dynamics properties, such as atom translational mobility, bond/segment reorientation dynamics, torsional dynamics, conformational transition rate and dynamic heterogeneity of the cis-PB chains, are analyzed in detail. It is found that Tg could be affected by the C60 weight fraction due to its inhibition effect on the mobility of the cis-PB chains. However, Tg is different, which depends on different dynamics scales. Among the chain dynamics properties, Tg is the lowest from atom translational mobility, while it is the highest from the dynamic heterogeneity. In addition, Tg can be more clearly distinguished from the dynamic heterogeneity; however, the conformational transition rate seems to be not very sensitive to the C60 weight fraction compared with others. For pure cis-PB chains, Tg and the activation energy in this work can be compared with those of other polymers. In addition, the temperature dependence of the dynamic properties has different Arrhenius behaviors above and below Tg. The activation energy below Tg is lower than that above Tg. This work can help to understand the effect of the C60 on the dynamic properties and glass transition temperature of the cis-PB chains from different scales.
2018, 36(1): 129-138
doi: 10.1007/s10118-018-2049-3
Abstract:
The stability of anion exchange membranes (AEMs) is an important feature of alkaline exchange membrane fuel cells (AEMFCs), which has been extensively studied. However it remains a real challenge due to the harsh working condition. Herein, we developed a novel type of polysulfone-based AEMs with three modified 1, 2-dimethylbenzimidazoliums containing different substitutes at C4- and C7-position. The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes. The swelling ratios of resultant AEMs were all lower than 10% after water immersion. The membrane with 4, 7-dimethoxy-1, 2-dimethylbenzimidazolium group exhibited the highest alkaline stability. Only 9.2% loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L-1 KOH solution at 80℃ for 336 h. Furthermore, the density functional theory (DFT) study on the three functional group models showed that the substitutes at C4- and C7-position affected the lowest unoccupied molecular orbital (LUMO) energies of the different 1, 2-dimethylbenzimidazolium groups.
The stability of anion exchange membranes (AEMs) is an important feature of alkaline exchange membrane fuel cells (AEMFCs), which has been extensively studied. However it remains a real challenge due to the harsh working condition. Herein, we developed a novel type of polysulfone-based AEMs with three modified 1, 2-dimethylbenzimidazoliums containing different substitutes at C4- and C7-position. The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes. The swelling ratios of resultant AEMs were all lower than 10% after water immersion. The membrane with 4, 7-dimethoxy-1, 2-dimethylbenzimidazolium group exhibited the highest alkaline stability. Only 9.2% loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L-1 KOH solution at 80℃ for 336 h. Furthermore, the density functional theory (DFT) study on the three functional group models showed that the substitutes at C4- and C7-position affected the lowest unoccupied molecular orbital (LUMO) energies of the different 1, 2-dimethylbenzimidazolium groups.
