WATER RESEARCH
·
2020
·
IF 9.13
Pan Hu,Shuhan Zhuang,Shaohang Shen,Yihan Yang,Hu Yang
Coagulation/flocculation is one of the most extensive and cost-effective pretreatments to improve the dewaterability of sludge in water treatment plants. In this study, three series of graft cationic starch (St)-based flocculants with distinct structural characteristics including charge density (CD), graft-chain length (L), and graft-chain distribution (N) were synthesized by graft copolymerization of [(2-methacryloyloxy-ethyl) trimethyl ammonium chloride] and acrylamide onto St backbone. The structural effects of these St-based flocculants on the sludge dewaterability have been quantitatively analyzed by using a second-order polynomial model according to phenomenological theory. The predicted dewatering performance and optimal dose were fully consistent with the experimental results. On the basis of this established model, the dewatering mechanisms were discussed in detail by combination of the analysis of the changes in filter cake moisture content, specific resistance of filtration, bound water content, compression coefficient, extracellular polymeric substances fractions and components, spatial distributions of proteins and polysaccharides, microstructures of sludge cake, and flocs properties in the dewatering process. This graft St-based flocculant, with the structural characteristics of high CD, long L, and low N, exhibited superior sludge dewaterability because of the enhanced charge neutralization and bridging flocculation effects. Among these three structural factors, CD played a more important role in improvement of sludge dewaterability than L and N due to the dominant effect of charge neutralization. This study provided a better understanding of structure-activity relationship of these grafting modified flocculants, which was of significant guidance for the exploit and design of novel and efficient flocculants for improvement of sludge dewaterability.
研究领域:
环境工程
·
污水处理
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DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 22
·52234
·
IF 3.057
Changkai Linghu,Lijin Xie,Le Yang,Xiaolong Li,Yao Tao,Yinhan Xu,Zhu Luo
Grafted maleic anhydrides (MAHs) are common compatibilizers, and the Epoxy (EP) group exhibits high activity of epoxy functional groups and strong affinity with both acidic and basic groups. Therefore, high efficiency and broad-spectrum compatibilizers can be obtained by grafting these two monomers onto the polymer molecular chain. In this study, the grafted MAH was used as the graft platform to add the second graft monomer, and the bisphenol A epoxy resin (E51) with two epoxy functional groups or the tri-epoxy functional triglycidyl isocyanurate (TGIC), was added into the polylactic acid molecular chain, in order to prepare the double-monomer grafted PLA compatibilizers. Three kinds of compatibilizers, polylactic acid grafted maleic anhydride (PLA-g-MAH), polylactic acid double grafted maleic anhydride/bisphenol A epoxy resin (PLA-g-MAH-E51), and polylactic acid double grafted maleic anhydride/triglycidyl isocyanurate (PLA-g-MAH-TGIC) were successfully prepared using this single-step method. Finally, FTIR and 1 H-NMR were adopted to measure the grafting degrees and structures of the grafted products. The grafting degree of PLA-g-MAH20% was 5.36%, the MAH and EP grafting degrees of PLA-g-MAH 20%-E51 6% were 2.47% and 1.15%, respectively, and the MAH and EP grafting degrees of PLA-g-MAH 20%-TGIC6% were 2.30% and 0.93%, respectively. A portion of that EP was grafted onto the PLA molecular chain by reacting with grafted anhydride, resulting in a decrease in the number of grafted anhydride groups.
研究领域:
材料科学
·
高分子化学
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DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2024
·
IF 5.8
Ziqian Xiang,Chuang Chen,Fang Chen,Wei Zhai
Due to the generation of reactive radicals during the collapse of acoustic cavitation bubbles, various polymerization reactions can be effectively carried out within homogeneous solution. However, hybrid nanostructured materials with controllable polymer grafting density through sonochemical polymerization remains challenging, primarily attributed to the complexity of the dynamic behavior of cavitation bubbles within heterogeneous polymerization system. In this study, a series of SiO 2 hybrid NPs (SiO 2 @PNIPAM and SiO 2 @PDEAEMA) with tunable grafting density are synthesized by the cavitation regulated sonochemical approach, and the surface grafting mechanism is interpreted. In specific, the incorporation of SiO 2 nanoparticles to the sonochemical solution not only modulates the dynamics of transient cavitation bubbles but also correspondingly increases the concentration of ultrasound induced-free radicals and the monomer conversion rate. In this scenario, the presence of ultrasound-generated free radicals facilitates rapid polymerization on the surface of SiO 2 and in the liquid phase at the same time, regardless of the chemical composition of monomer. Under the combined action of the two, the long-linked polymers with uniform distribution are formed by coupling. Besides, by adjusting the ultrasound-aeration cycle, the active sites on the surface of the SiO 2 gradually increase, which also promotes the density of the grafted polymer to gradually increase. This study offers the possibility for sonochemical polymerization of organic-inorganic hybrid nanomaterials with tunable structure.
研究领域:
材料科学
·
化学工程
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DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Hui Zou,Xiancheng Ren,Jing Zhang
In this study, a superior hydrophilic polyvinylidene fluoride (PVDF) membrane with an enhanced monomer grafting ratio was prepared via an ultraviolet (UV) photografting polymerization method. The water contact angle (WCA) of the Bi2O3–acrylic acid (AA)-modified PVDF membrane reduces to 40.4° with the increasing of Bi2O3 content, illustrating significant enhancement of membrane hydrophilicity. Attenuated total reflection Fourier transform infrared spectra and atomic absorption spectroscopy reveal that Bi2O3–AA-modified membranes have more than five times AA grafting degree onto the surface of the hydrophobic PVDF membranes than only the AA-modified membrane. The mechanism of Bi2O3 promoting degree of AA grafting during the polymerization process is also especially explored in this research, and h+ and •O2– are proved to be primary active species in graft polymerization. Unexpectedly, the modified membrane has much better retention performance compared with the neat membrane. In addition, the Bi2O3–AA modified membrane also shows self-cleaning property for degradation dyes on the membrane surface.
研究领域:
材料科学
·
环境工程
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DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 23
·5253
·
IF 4.967
Xin Zheng,Lina He,Guipeng Yu,Yongjin Li
It is considered to be one of the most effective strategies to prepare functionalized polypropylene (PP) materials via the melt grafting of polar monomers onto PP chains. However, the grafting efficiency of functional monomers is generally low. To achieve a high grafting efficiency, we explored the effect of tea polyphenols (C), which are good free radical scavengers, on the melt grafting of glycidyl methacrylate (GMA) onto PP chains initiated by dicumyl peroxide (DCP). Specifically, 0.5~3 wt% of tea polyphenols (C) were introduced to the PP/DCP/GMA melt blending system. The morphology, melt flow rate (MFR), thermal and mechanical properties of tea polyphenols (C) incorporated PP/DCP/GMA blends were investigated systematically. The results showed that the proper amount of tea polyphenols (C) (0.5~2 wt%) promoted the grafting of GMA. Unexpectedly, the PP backbone suffered from more severe degradation with the addition of tea polyphenols (C). The phenomena were ascribed to the reaction between phenolic hydroxyl groups of tea polyphenols (C) and epoxy groups of grafted GMA, which was revealed by the FTIR results. In addition, according to DSC and the tensile test, the co-grafting of GMA and tea polyphenols (C) improved the crystallization ability, yield strength and Young’s modulus of the PP matrix.Keywords:polypropylene;melt grafting;glycidyl methacrylate;tea polyphenols (C);co-grafting
研究领域:
材料科学
·
高分子化学
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PubMed
高影响因子
MACROMOLECULES
·
2022
·
IF 6.057
Jianing Zhou,Jinxian Yang,Muhammad Waqas Ishaq,Lianwei Li
Exploring the difference in the topology–structure–conformation relationship for linear and cyclic graft polymers is an interesting topic. In this work, two libraries of linear graft (l-PPA-g-PS, with a linear backbone) and cyclic graft (c-PPA-g-PS, with a cyclic backbone) polystyrenes with low ratios of the backbone-to-sidechain contour length (rc, from 1.26 to 6.22) and various grafting densities (σ, from 0.16 to 0.86) have been studied as models. Atomic force microscopy (AFM) characterization has indicated ellipsoidal and spherical morphologies for both l-PPA-g-PS and c-PPA-g-PS with no significant difference. By comparing the absolute (Mw,abs) and apparent (Mw,app) molar masses, it is found that Mw,abs/Mw,app varies from 1.5 to 3.5 and gradually increases with σ. By measuring gh1/2 (gh1/2 = Rh,graft/Rh,linear), it is found that the two topologies have different compactness of conformation. By following the temperature-dependent interchain aggregation in cyclohexane, it is found that the cyclic backbone feature can suppress the interchain association and be more susceptible to graft density than linear graft polymers. The present study has clearly showed that the cyclic graft topology can potentially display unique structural and conformational properties, which can be attributed to the topological advantages such as more compact conformation and significant isotropic features.
研究领域:
聚合物科学
·
材料科学
·
物理化学
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DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Pirah Ayaz,Xi Liu,Yuyun Yu,Shuangfei Xiang,Shujun Zhao,Feiya Fu,Hongyan Diao,Xiangdong Liu
Covalent immobilization of antibacterial peptides (APs) onto silk protein-based materials has always been a challenge due to the lack of green and efficient macromolecular cross-linkers. Here, we proposed a dialdehyde polysaccharide cross-linker oxidized from pullulan for grafting a natural AP protamine (PM) onto silk fiber surface through a simple cold pad-batch process. The oxidized pullulan (OP) was linked to silk fiber surface through Schiff reaction and used for mediated cross-linking of PM also via Schiff base linkages. This modification introduced abundant PM guanidine groups on the fiber leading to much-desired antibacterial activity, and considerable improvement in the moisture transfer properties and shade depth. FTIR, XPS, SEM studies confirmed the presence of PM and the cross-linking structure between the polysaccharide and peptides on the fiber surfaces. The antibacterial activity imparted by this process was retained even after 20 washing and 50 rubbing cycles proving versatility and durability. Further, the process did not affect other critical silk properties such as appearance, tensile strength, biological safety, etc. Immobilization of PM onto silk fibers through this novel green polysaccharide cross-linker makes silk more appealing and usable and could also enlighten the attempts of cross-linking other protein materials.
研究领域:
材料科学
·
纺织工程
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DOI
PubMed
高影响因子
POLYMER INTERNATIONAL
·
2014
·Vol. 64
·期 6
·804-810
·
IF 2.247
Jiming Yang,Ning Zhang,Haolong Li,Bin Xu,Wenjing Tian,Dewen Dong
A facile and efficient strategy for the preparation of polymer grafts on zirconia particles is developed by means of self-initiated photografting and photopolymerization. The UV-induced grafting polymerization is applicable to a variety of polymerizable monomers, allowing the direct formation of homogeneous and stable polymer coatings on zirconia particles without any initiator immobilization. The as-prepared polymer grafts are proved to be efficient supports for polyoxometalates as H 3 PW 12 O 40 can be uniformly and stably immobilized on a poly(4-vinylpyridine) layer through electrostatic interaction. The resulting hybrid catalyst system, associated with high catalytic activity for a series of oxidation reactions such as amines, alkenes, alcohols and sulfides, represents a novel and efficient system with a high catalyst loading capacity and stability upon reuse in further cycles. © 2014 Society of Chemical Industry
研究领域:
材料科学
·
催化化学
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DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2024
·
IF 5.7
Yumin Wang,Songbai Liu
Conventional radical grafting of proteins with catechins consumed the most antioxidant-active hydroxyls during grafting, thus failing to effectively retain antioxidant activity in conjugates. In this study, a novel strategy of selective protection of the most reactive hydroxyls before grafting was developed to preserve the most reactive hydroxyls and effectively retain antioxidant activity in conjugates. Selective protection of the most reactive hydroxyls of (−)-epigallocatechin-3-gallate (EGCG) was successfully realized in a yield of 87% applying trimethyl orthopropionate and catalytic calcium triflate at 40 °C. The novel ovalbumin (OVA)–EGCG conjugate with 93% grafting ratio was prepared by radical grafting with the selectively protected EGCG and subsequent deprotection. Substantially enhanced antioxidant performance of the novel OVA–EGCG conjugate in liposomes was unveiled with notably reduced curcumin degradation and leakage. The strategy and approaches developed in this study will be valuable to effectively improve the antioxidant activities of protein–catechin grafting conjugates.
研究领域:
食品科学
·
化学
·
生物技术
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DOI
PubMed
高影响因子
Polymers
·
2019
·Vol. 11
·期 5
·843
·
IF 3.164
Kangjun Xie,Zhen Dong,Yicheng Wang,Wei Qi,Maolin Zhai,Long Zhao
A novel amphoteric ion exchange membrane (AIEM) was successfully prepared by one-step radiation grafting of sodium styrene sulfonate (SSS) and dimethylaminoethyl methacrylate (DMAEMA) onto ethylene-vinylalcohol copolymer (EVOH) powder and sequent transferring into film by casting method. Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analyzer (TGA) and elemental analysis testified SSS and DMAEMA were successfully grafted onto EVOH. The ion exchange capacity, water uptake and proton conductivity of the resulting AIEM increased with grafting yield (GY). At the GY of 40.9%, the permeability of vanadium ions of AIEM was 3.98 × 10−7cm2min−1, which was better than Nafion117 membrane. Furthermore, the cost of this AIEM is much lower than that of Nafion117 membrane. This work provided a low cost and simple method for fabrication of the ion exchange membrane for vanadium redox flow battery (VRFB). Meanwhile, it also provided a new direction for the application of EVOH.Keywords:radiation grafting;ion exchange membrane;EVOH;VRFB
研究领域:
材料科学
·
电化学
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DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 36
·30320-30329
·
IF 3.289
Xuefei Leng,Zhiyong Wei,Yufei Bian,Yingying Ren,Yurong Wang,Qinyi Wang,Yang Li
Three series of narrowly dispersed comb-like graft poly(L-lactide) (PLLA) with controlled graft length and graft density have been facilely synthesized and characterized. The structural information was determined by means of 1H NMR, GPC, and viscometry, demonstrating the well-defined grafted structure. The effects of grafting parameters on rheological properties, thermal and crystallization behaviors were investigated systematically to illustrate the structure–property relationships. By the analysis of the rheological behavior, the increase of graft length and graft density can both lead to an elevated value of zero-viscosity (η0), enhanced complex modulus (G*) and increased complex viscosity (η*). Comparatively, graft density contributes more to the improvement of rheological properties than graft length does. For thermal properties, DSC results show that the glass transition temperature (Tg), the melting temperature (Tm) and the crystallization enthalpy (ΔHm) of graft PLLA increase with the chain length and decrease with the graft density. Furthermore, spherulite morphologies and growth rates were studied by polarized microscopy (POM), and the observation revealed a remarkable improvement of radius growth rate of the spherulites (G) when graft density increased. The results indicate that G depends more on the molecular weight of each arm (Mn,arm) than the total Mn.
研究领域:
高分子科学
·
材料科学
·
化学工程
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DOI
高影响因子
Polymers
·
2019
·Vol. 11
·期 6
·962
·
IF 3.164
Jifu Du,Zhen Dong,Yuxuan Pi,Xin Yang,Long Zhao
Two kinds of cotton linter-based adsorbents were synthesized by grafting dimethylaminoethyl methacrylate (DMAEMA) on cotton linter via radiation grafting polymerization, followed by further quaternization (QCL) or protonation (PCL). The effect of radiation dose and monomer concentration on grafting yield was optimized. The synthesized adsorbents were characterized by Fourier transform infrared spectrometry (FT-IR), Thermogravimetric Analysis (TGA), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The adsorption behaviors of the two adsorbents toward humic acid (HA) were investigated and discussed. pH effect studies showed that QCL was pH-independent, whereas PCL was just suitable for HA adsorption with pH < 6. The adsorption kinetics of the PCL and QCL adsorbent for HA removal were better described by pseudo-second-order kinetic mode and reached equilibrium in 40 min. The adsorption isotherms of the PCL and QCL adsorbent were well fitted with both Langmuir and Freundlich isotherm models, for which adsorption capacity reached 250 mg/g and 333 mg/g at pH 6, respectively. XPS analysis revealed the ratio of two amino group species at different pH, suggesting that the interaction mechanism of the adsorbent and HA was electrostatic adsorption.Keywords:cotton linter;humic acid;adsorption;radiation grafting
研究领域:
环境科学
·
材料科学
·
化学工程
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DOI
PubMed
高影响因子
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