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2017 Volume 35 Issue 7
2017, 35(7): 793-798
doi: 10.1007/s10118-017-1949-y
Abstract:
Dendrimers are considered as a promising family of organic second-order nonlinear optical (NLO) polymers because of their well-defined structures, easily modified peripheral functional groups, interior branches and central cores. In order to obtain NLO materials with high performance, dendrimer structures have been optimized in the past years, such as the "branch only" and the "root containing" type dendrimers. This feature article highlights the achievements in exploring the rational design of dendrimers, partially marked by their macroscopic NLO performance.
Dendrimers are considered as a promising family of organic second-order nonlinear optical (NLO) polymers because of their well-defined structures, easily modified peripheral functional groups, interior branches and central cores. In order to obtain NLO materials with high performance, dendrimer structures have been optimized in the past years, such as the "branch only" and the "root containing" type dendrimers. This feature article highlights the achievements in exploring the rational design of dendrimers, partially marked by their macroscopic NLO performance.
2017, 35(7): 799-808
doi: 10.1007/s10118-017-1946-1
Abstract:
Polymer/metal composite segmental Janus nanoparticles (NPs) are synthesized by sequential growth against poly(4-vinylpyridine) (P4VP) crosslinked cP4VP-PS Janus NPs. A Janus cluster of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) diblock copolymer is self-organized after absorption onto a silica patchy sphere via hydrogen bonding. Selective crosslinking of P4VP leads to the formation of robust cP4VP-PS Janus NPs. Within the cP4VP domain, functional species such as metals are preferentially grown by in situ reduction. Other thiol-capped polymers, for example, thiol-capped poly(N-isopropylacrylamide) (PNIPAM-SH), can be conjugated onto the opposite side to form polymer/metal triple segmental Janus NPs. The hyperthermia effect of Au NP of PNIPAM-Au@cP4VP-PS by near infrared (NIR) irradiation can trigger a fast transition from amphiphilic to hydrophobic of the Janus NPs at low surrounding temperature. De-stabilization of the emulsion is NIR triggered although the system temperature is below LCST (~32℃).
Polymer/metal composite segmental Janus nanoparticles (NPs) are synthesized by sequential growth against poly(4-vinylpyridine) (P4VP) crosslinked cP4VP-PS Janus NPs. A Janus cluster of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) diblock copolymer is self-organized after absorption onto a silica patchy sphere via hydrogen bonding. Selective crosslinking of P4VP leads to the formation of robust cP4VP-PS Janus NPs. Within the cP4VP domain, functional species such as metals are preferentially grown by in situ reduction. Other thiol-capped polymers, for example, thiol-capped poly(N-isopropylacrylamide) (PNIPAM-SH), can be conjugated onto the opposite side to form polymer/metal triple segmental Janus NPs. The hyperthermia effect of Au NP of PNIPAM-Au@cP4VP-PS by near infrared (NIR) irradiation can trigger a fast transition from amphiphilic to hydrophobic of the Janus NPs at low surrounding temperature. De-stabilization of the emulsion is NIR triggered although the system temperature is below LCST (~32℃).
2017, 35(7): 809-822
doi: 10.1007/s10118-017-1944-3
Abstract:
A silver nanoparticles-poly(carboxybetaine methacrylate) (AgNPs-PCBMA) nanocomposite was prepared on poly(vinylidene fluoride) (PVDF) membrane surface to improve its hydrophilicity and antifouling properties. Firstly, the PVDF membranes were grafted by PCBMA via physisorbed free radical grafting technique. Then Ag+ coordinated to the carbonyl group on PCBMA and subsequently was reduced to silver nanoparticles. The hydrophilicity of the PVDF-g-PCBMA/Ag membrane was enhanced with the increasing fixed degree (FD) of AgNPs, and the original water contact angle of membrane was reduced to 33.97°. Additionally, water flux recovery ratio (FRR) and bovine serum albumin (BSA) rejection ratio of PVDF-g-PCBMA/AgNPs membrane were improved from 52% to 93.32% and 28.12% to 91.12%, respectively. Further, the PVDF-g-PCBMA/AgNPs membranes exhibited the more pronounced inhibition zone. The study demonstrated that compared with pure AgNPs or the PCBMA polymer brush, the synergistic effect of PCBMA and AgNPs made PVDF membranes have better hydrophilicity and anti-bacterial performances.
A silver nanoparticles-poly(carboxybetaine methacrylate) (AgNPs-PCBMA) nanocomposite was prepared on poly(vinylidene fluoride) (PVDF) membrane surface to improve its hydrophilicity and antifouling properties. Firstly, the PVDF membranes were grafted by PCBMA via physisorbed free radical grafting technique. Then Ag+ coordinated to the carbonyl group on PCBMA and subsequently was reduced to silver nanoparticles. The hydrophilicity of the PVDF-g-PCBMA/Ag membrane was enhanced with the increasing fixed degree (FD) of AgNPs, and the original water contact angle of membrane was reduced to 33.97°. Additionally, water flux recovery ratio (FRR) and bovine serum albumin (BSA) rejection ratio of PVDF-g-PCBMA/AgNPs membrane were improved from 52% to 93.32% and 28.12% to 91.12%, respectively. Further, the PVDF-g-PCBMA/AgNPs membranes exhibited the more pronounced inhibition zone. The study demonstrated that compared with pure AgNPs or the PCBMA polymer brush, the synergistic effect of PCBMA and AgNPs made PVDF membranes have better hydrophilicity and anti-bacterial performances.
2017, 35(7): 823-836
doi: 10.1007/s10118-017-1941-6
Abstract:
A series of hydroxide conductive polymers QTBMs carrying dense aromatic side-chain quaternary ammonium groups has been synthesized by using a new monomer of 3, 3'-di(3", 5"-dimethylphenyl)-4, 4'-difluorodiphenyl sulfone and other commercial monomers via polycondensation reaction, and subsequent bromination, quaternization and alkalization. The chemical structures of the ionomers were confirmed by 1H-and 13C-NMR spectroscopy. Water uptake, swelling ratio, hydroxide conductivity, the number of bonded water per ammonium group (λ), volumetric ion exchange capacity (IECVwet), mechanical and thermal properties, and chemical stability were systematically evaluated for the series of QTBMs membranes. QTBMs showed IECs ranging from 1.02 meq·g-1 to 2.11 meq·g-1; in particular, QTBM-60 membrane with the highest IEC (2.11 meq·g-1) had very high hydroxide ion conductivity of 131.9 mS·cm-1 at 80℃, which was attributed to the well assembled nano-channels with distinct phase separation evidenced by small-angle X-ray scattering (SAXS). It was found that the hydrated QTBMs membranes were mechanically stable with moderate water uptakes and swelling ratios, high chemical stability under the harsh alkaline conditions. This work provides a facile way to prepare anion exchange membranes (AEMs) with high performances for the application in alkaline fuel cells.
A series of hydroxide conductive polymers QTBMs carrying dense aromatic side-chain quaternary ammonium groups has been synthesized by using a new monomer of 3, 3'-di(3", 5"-dimethylphenyl)-4, 4'-difluorodiphenyl sulfone and other commercial monomers via polycondensation reaction, and subsequent bromination, quaternization and alkalization. The chemical structures of the ionomers were confirmed by 1H-and 13C-NMR spectroscopy. Water uptake, swelling ratio, hydroxide conductivity, the number of bonded water per ammonium group (λ), volumetric ion exchange capacity (IECVwet), mechanical and thermal properties, and chemical stability were systematically evaluated for the series of QTBMs membranes. QTBMs showed IECs ranging from 1.02 meq·g-1 to 2.11 meq·g-1; in particular, QTBM-60 membrane with the highest IEC (2.11 meq·g-1) had very high hydroxide ion conductivity of 131.9 mS·cm-1 at 80℃, which was attributed to the well assembled nano-channels with distinct phase separation evidenced by small-angle X-ray scattering (SAXS). It was found that the hydrated QTBMs membranes were mechanically stable with moderate water uptakes and swelling ratios, high chemical stability under the harsh alkaline conditions. This work provides a facile way to prepare anion exchange membranes (AEMs) with high performances for the application in alkaline fuel cells.
2017, 35(7): 837-845
doi: 10.1007/s10118-017-1940-7
Abstract:
Porous hybrid microspheres were fabricated by the synthesized calcium gluconate-g-poly(D, L-lactide) (CG-g-PDLLA) composites. These hybrid microspheres were treated with an alkaline solution for different period of time to control the amount of generated carboxylate groups and remained CG on the surface. The microspheres were then incubated in a supersaturated simulated body fluid (1.5 SBF) solution for different time to investigate their biomimetic mineralization behavior. The depositions were found to have a fine cluster morphology, a similar crystal structure and chemical structure to natural hydroxyapatite, and a medium Ca/P of approximately 1.30. The effect of surface treating time on the structure and mineralization behavior of these microspheres has been discussed in detail. The results indicate that the nucleation and growth of apatite on the surface are influenced by the induced carboxylate groups and the remained CG. The hybrid CG-g-PDLLA microspheres have the potential as a novel alternative in bone tissue engineering.
Porous hybrid microspheres were fabricated by the synthesized calcium gluconate-g-poly(D, L-lactide) (CG-g-PDLLA) composites. These hybrid microspheres were treated with an alkaline solution for different period of time to control the amount of generated carboxylate groups and remained CG on the surface. The microspheres were then incubated in a supersaturated simulated body fluid (1.5 SBF) solution for different time to investigate their biomimetic mineralization behavior. The depositions were found to have a fine cluster morphology, a similar crystal structure and chemical structure to natural hydroxyapatite, and a medium Ca/P of approximately 1.30. The effect of surface treating time on the structure and mineralization behavior of these microspheres has been discussed in detail. The results indicate that the nucleation and growth of apatite on the surface are influenced by the induced carboxylate groups and the remained CG. The hybrid CG-g-PDLLA microspheres have the potential as a novel alternative in bone tissue engineering.
2017, 35(7): 846-856
doi: 10.1007/s10118-017-1943-4
Abstract:
Polysulfone (PSF) membranes have gained great attention in the fields of ultrafiltration, microfiltration, and thin film composite membranes for nanofiltration or reverse osmosis. For the first time, it is proposed to fabricate PSF membranes via thermally induced phase separation (TIPS) process using diphenyl sulfone (DPSO2) and polyethylene glycol (PEG) as mixed diluent. DPSO2 is chosen as a crystallizable diluent, while PEG is considered in terms of molecular weight (Mw) and dosage. We systematically investigate the interactions between PSF, DPSO2 and PEG based on the simulation calculations and solubility parameter theory. It is inferred that DPSO2 has an excellent compatibility with PSF, and the addition of PEG results in the ternary system thermodynamically less stable and then facilitates its liquid-liquid (L-L) phase separation. SEM images indicate that cellular-like pores are obvious throughout the membrane when the PEG content in the mixed diluent is 25 wt%-35 wt%. We can facilely manipulate the pore size, water flux and mechanical properties of PSF membranes with the dosage of PEG-200, the Mw of PEG or the cooling rate. The successful application of TIPS can provide a new approach for structure manipulation and performance enhancement of PSF membranes.
Polysulfone (PSF) membranes have gained great attention in the fields of ultrafiltration, microfiltration, and thin film composite membranes for nanofiltration or reverse osmosis. For the first time, it is proposed to fabricate PSF membranes via thermally induced phase separation (TIPS) process using diphenyl sulfone (DPSO2) and polyethylene glycol (PEG) as mixed diluent. DPSO2 is chosen as a crystallizable diluent, while PEG is considered in terms of molecular weight (Mw) and dosage. We systematically investigate the interactions between PSF, DPSO2 and PEG based on the simulation calculations and solubility parameter theory. It is inferred that DPSO2 has an excellent compatibility with PSF, and the addition of PEG results in the ternary system thermodynamically less stable and then facilitates its liquid-liquid (L-L) phase separation. SEM images indicate that cellular-like pores are obvious throughout the membrane when the PEG content in the mixed diluent is 25 wt%-35 wt%. We can facilely manipulate the pore size, water flux and mechanical properties of PSF membranes with the dosage of PEG-200, the Mw of PEG or the cooling rate. The successful application of TIPS can provide a new approach for structure manipulation and performance enhancement of PSF membranes.
2017, 35(7): 857-865
doi: 10.1007/s10118-017-1934-5
Abstract:
A novel environment-friendly system is proposed to fabricate polymer brush, which has the advantages including non-toxic and inexpensive initiator (eosin Y), visible-light exposure (λ= 515 nm), water medium and ambient environment. The experimental results from UV-Vis spectroscopy, AFM-based single molecule force spectroscopy (SMFS) and other measurements indicate that a polymer brush with a living nature is fabricated via free radical polymerization. This polymer brush may find applications in coatings, bio-interfaces and so forth.
A novel environment-friendly system is proposed to fabricate polymer brush, which has the advantages including non-toxic and inexpensive initiator (eosin Y), visible-light exposure (λ= 515 nm), water medium and ambient environment. The experimental results from UV-Vis spectroscopy, AFM-based single molecule force spectroscopy (SMFS) and other measurements indicate that a polymer brush with a living nature is fabricated via free radical polymerization. This polymer brush may find applications in coatings, bio-interfaces and so forth.
2017, 35(7): 866-873
doi: 10.1007/s10118-017-1933-6
Abstract:
Herein, we demonstrate the synthesis of a well-defined diblock copolymer consisting of isotactic polystyrene (iPS) and linear polyethylene, isotactic polystyrene-block-polyethylene (iPS-b-PE), by the combination of sequential monomer addition and hydrogenation. Isospecific living polymerization of styrene and living trans-1,4-polymerization of 1,3-butadiene were catalyzed by 1,4-dithiabutandiyl-2,2′-bis(6-cumenyl-4-methylphenoxy) titanium dichloride (complex 1) activated by triisobutyl aluminum modified methylaluminoxane (MMAO) at room temperature to provide highly isotactic polystyrene (iPS) and 1,4-trans-polybutadiene (1,4-trans-PBD) with narrow molecular weight distribution. Furthermore, the iPS-b-1,4-trans-PBD was synthesized via sequential monomer addition in the presence of complex 1 and MMAO. The hydrogenation of the 1,4-trans-PBD block was promoted by RuCl2(PPh3)3 used as a catalyst to produce iPS-b-PE.
Herein, we demonstrate the synthesis of a well-defined diblock copolymer consisting of isotactic polystyrene (iPS) and linear polyethylene, isotactic polystyrene-block-polyethylene (iPS-b-PE), by the combination of sequential monomer addition and hydrogenation. Isospecific living polymerization of styrene and living trans-1,4-polymerization of 1,3-butadiene were catalyzed by 1,4-dithiabutandiyl-2,2′-bis(6-cumenyl-4-methylphenoxy) titanium dichloride (complex 1) activated by triisobutyl aluminum modified methylaluminoxane (MMAO) at room temperature to provide highly isotactic polystyrene (iPS) and 1,4-trans-polybutadiene (1,4-trans-PBD) with narrow molecular weight distribution. Furthermore, the iPS-b-1,4-trans-PBD was synthesized via sequential monomer addition in the presence of complex 1 and MMAO. The hydrogenation of the 1,4-trans-PBD block was promoted by RuCl2(PPh3)3 used as a catalyst to produce iPS-b-PE.
2017, 35(7): 874-886
doi: 10.1007/s10118-017-1915-8
Abstract:
We use a Monte Carlo method to study the phase and interfacial behaviors of A-b-B diblocks in a blend of homopolymers, A and B, which are confined between two asymmetric hard and impenetrable walls. Our results show that, when the interaction strength is weak, the block copolymers are uniformly distributed in the ternary mixtures under considered concentrations. Under strong interaction strength, distribution region of the block copolymers changes from a single smooth interface to a curved interface or multi-layer interface in the ternary mixtures. Furthermore, our findings show that with increasing volume fraction of A-b-B diblock copolymer (ϕC), copolymer profiles broaden while ϕC ≥ 0.4, a lamellar phase is formed and by further increasing ϕC, more thinner layers are observed. Moreover, the results show that, with the increase of ϕC, the phase interface first gradually transforms from plane to a curved surface rather than micelle or lamellar phase while with the increase of the interaction between A and B segments (εAB), the copolymer chains not only get stretched in the direction perpendicular to the interface, but also are oriented. The simulations also reveal that the difference between symmetric and asymmetric copolymers is negligible in statistics if the lengths of two blocks are comparable.
We use a Monte Carlo method to study the phase and interfacial behaviors of A-b-B diblocks in a blend of homopolymers, A and B, which are confined between two asymmetric hard and impenetrable walls. Our results show that, when the interaction strength is weak, the block copolymers are uniformly distributed in the ternary mixtures under considered concentrations. Under strong interaction strength, distribution region of the block copolymers changes from a single smooth interface to a curved interface or multi-layer interface in the ternary mixtures. Furthermore, our findings show that with increasing volume fraction of A-b-B diblock copolymer (ϕC), copolymer profiles broaden while ϕC ≥ 0.4, a lamellar phase is formed and by further increasing ϕC, more thinner layers are observed. Moreover, the results show that, with the increase of ϕC, the phase interface first gradually transforms from plane to a curved surface rather than micelle or lamellar phase while with the increase of the interaction between A and B segments (εAB), the copolymer chains not only get stretched in the direction perpendicular to the interface, but also are oriented. The simulations also reveal that the difference between symmetric and asymmetric copolymers is negligible in statistics if the lengths of two blocks are comparable.
2017, 35(7): 887-896
doi: 10.1007/s10118-017-1930-9
Abstract:
Marine economy is seriously affected by marine biofouling, which has plagued people for thousands of years. Although various strategies have been developed to protect artificial surfaces against marine biofouling, cost-effective biofouling-resistant coating is still a goal in pursue. Herein, a cost-effective liquid-infused porous slippery surface (LIPSS) was facilely prepared by using poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer to form microsphere surfaces, followed by infusing fluorocarbon lubricants into the porous structure. The as-prepared slippery surfaces were characterized by static water contact angle, sliding velocity and sliding angle analysis. We also investigated the adhesion behavior of Escherichia coli (E. coli) and limnetic algae on different surfaces. It is confirmed that the slippery surfaces have better anti-biofouling properties than the porous SEBS reference. This cost-effective approach is feasible and easily produced, and may potentially be used as fouling-resistant surfaces.
Marine economy is seriously affected by marine biofouling, which has plagued people for thousands of years. Although various strategies have been developed to protect artificial surfaces against marine biofouling, cost-effective biofouling-resistant coating is still a goal in pursue. Herein, a cost-effective liquid-infused porous slippery surface (LIPSS) was facilely prepared by using poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer to form microsphere surfaces, followed by infusing fluorocarbon lubricants into the porous structure. The as-prepared slippery surfaces were characterized by static water contact angle, sliding velocity and sliding angle analysis. We also investigated the adhesion behavior of Escherichia coli (E. coli) and limnetic algae on different surfaces. It is confirmed that the slippery surfaces have better anti-biofouling properties than the porous SEBS reference. This cost-effective approach is feasible and easily produced, and may potentially be used as fouling-resistant surfaces.
2017, 35(7): 897-908
doi: 10.1007/s10118-017-1931-8
Abstract:
Layered materials (MMT, LDH) were successfully modified by chain end functionalized polyethylene via an ion exchange method. The samples were characterized by using elemental analysis, Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results demonstrated that MMT was successfully exfoliated with the disappearance of [001] peak. For the LDH, the peak[003] moved to a low angle and greatly weakened, indicating that LDH was successfully functionalized and completely intercalated or exfoliated. HDPE/layered nanocomposites were obtained between HDPE and different content of functional layered materials. The SEM and TEM results of nanocomposites showed the layered materials were well dispersed in the HDPE matrix, with a particle size of 100-200 nm.
Layered materials (MMT, LDH) were successfully modified by chain end functionalized polyethylene via an ion exchange method. The samples were characterized by using elemental analysis, Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results demonstrated that MMT was successfully exfoliated with the disappearance of [001] peak. For the LDH, the peak[003] moved to a low angle and greatly weakened, indicating that LDH was successfully functionalized and completely intercalated or exfoliated. HDPE/layered nanocomposites were obtained between HDPE and different content of functional layered materials. The SEM and TEM results of nanocomposites showed the layered materials were well dispersed in the HDPE matrix, with a particle size of 100-200 nm.
