LANGMUIR
·
2017
·
IF 3.833
Jian Zhang,Ran Kou,Guangming Liu
Strong polyelectrolyte brushes (SPB) and weak polyelectrolyte brushes (WPB) have different origins with response to pH, which makes their pH-responsive properties sensitive to salt concentration in different ways. Herein, we have employed poly[2-(methacryloyloxy)ethyl trimethylammonium chloride] (PMETAC) and poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) brushes as model systems for SPB and WPB, respectively, to investigate the effect of salt concentration on the pH responses of SPB and WPB using several surface-sensitive techniques. The pH-responsive properties of the PMETAC brushes are governed by the reorganization of the interchain hydrogen bonds between the grafted chains, whereas the pH response of the PDMAEMA brushes is controlled by the charge of the grafted chains. The response of the properties of the PMETAC brushes including hydration, conformation, and surface wettability becomes weaker with increasing salt concentration induced by the competitive adsorption of counterions to the brushes between OH– and Cl–. The weakening of the pH response of the PMETAC brushes is more remarkable at the relatively high pH values. The pH response of the PDMAEMA brushes also exhibits a salt-concentration dependence. As the salt concentration increases, the weakening of the pH response of the PDMAEMA brushes is attributed to the decrease in osmotic pressure within the brushes at relatively low pH values.
研究领域:
材料科学
·
表面化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2020
·
IF 3.557
Tao Wang,Ran Kou,Jian Zhang,Renwei Zhu,Hongtao Cai,Guangming Liu
In this work, a negatively charged poly(3-sulfopropyl methacrylate potassium) (PSPMA) brush has been employed as a model system to demonstrate the tuning of the light response of strong polyelectrolyte brushes (SPBs) with counterions. The substitution of K+ counterions by azobenzene-containing counterions (Azo-N+) renders the PSPMA brush light-responsive in aqueous solutions. Nevertheless, the strength of the light response of the PSPMA brush is weak due to the inefficient disassembly of the micelle-like aggregates in the brush upon irradiation with ultraviolet light. Counterion mixtures of Azo-N+ and K+ are employed to realize a strong light response of the PSPMA brush by incorporating a reasonable amount of Azo-N+ counterions into the brush. The strength of the light response of the PSPMA brush can be tuned by the mole ratio of Azo-N+ to K+. Furthermore, properties including the hydration and conformation of the PSPMA brush can be reversibly switched via alternating ultraviolet and visible light irradiation. This work opens up the opportunities available for the use of counterions to tune the light response of SPBs.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
Polymers
·
2020
·Vol. 12
·期 4
·746
·
IF 3.426
Yu Huang,Xiaogang Xue,Kaiqiao Fu
In this paper, a microparticle system consisting of cationic polyacrylamide (CPAM) and anionic spherical polyelectrolyte brushes (ASPB) is proposed to improve the retention of pulp suspension containing bleached reed kraft pulp and precipitated calcium carbonate (PCC). We first describe the preparation of ASPB. The ASPB, consisting of a carbon sphere (CS) core and a shell of sodium polystyrene sulfonate (PSSNa) brushes, was synthesized by surface-initiated polymerization. The structure and morphology of ASPB were characterized by Fourier-transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Then, flocculation and retention of pulp suspension by a CPAM/ASPB dual-component system were examined. Our results indicate that more highly effective flocculation and higher retention efficiency could be achieved simultaneously by a CPAM/ASPB dual-component system when compared to the conventional microparticle system. Bridging flocculation and electrostatic attraction might be the main flocculation mechanism for CPAM/ASPB systems.Keywords:anionic spherical polyelectrolyte brushes;flocculation;retention;mechanism
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanoscale Research Letters
·
2014
·Vol. 9
·期 1
·1-6
·
IF 2.481
Zhang Qi,Li Houbin,Zhang Pan,Liu Liangliang,He Yuhang,Wang Yali
Modified carbon spheres (CSPBs) were obtained by grafting poly(diallyl dimethyl ammonium chloride) (p-DMDAAC) on the surface of carbon spheres (CSs). It can be viewed as a kind of cation spherical polyelectrolyte brushes (CSPBs), which consist of carbon spheres as core and polyelectrolytes as shell. The method of synthesizing carbon spheres was hydrothermal reaction. Before the polyelectrolyte brushes were grafted, azo initiator [4,4′-Azobis(4-cyanovaleric acyl chloride)] was attached to the carbon spheres' surface through hydroxyl groups. CSPBs were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), conductivity meter, and system zeta potential. The results showed that compared with carbon spheres, the conductivity and zeta potential on CSPBs increased from 9.98 to 49.24 μS/cm and 11.6 to 42.5 mV, respectively, after the polyelectrolyte brushes were grafted. The colloidal stability in water was enhanced, and at the same time, the average diameter of the CSPBs was found to be 173 nm, and the average molecular weight and grafted density of the grafted polyelectrolyte brushes were 780,138 g/mol and 4.026 × 10 9 /nm 2, respectively.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2014
·
IF 4.384
Tao Wang,Yunchao Long,Lvdan Liu,Xiaowen Wang,Vincent S. J. Craig,Guangzhao Zhang,Guangming Liu
We have investigated changes in the cation-specific conformational behavior of poly(sodium styrenesulfonate) (PSS) brushes as the solvent changes from water to methanol using a quartz crystal microbalance with dissipation (QCM-D). A solvation to desolvation transition of the grafted chains accompanied by swelling to the collapse transition of the brushes is observed for Na+. In the case of Cs+, the brushes undergo solvation to desolvation to resolvation accompanied by swelling to collapse to reswelling transitions. The resolvation and reswelling transitions for Cs+ are induced by the charge inversion of the brushes via van der Waals interactions between Cs+ and the brushes. All of the transitions for monovalent cations become less obvious as the methanol content increases. For divalent Ca2+ and trivalent La3+, a solvation to desolvation to resolvation transition of the grafted chains accompanied by a swelling to collapse to reswelling transition of the brushes can be observed. The resolvation and reswelling of the brushes for the multivalent cations are induced by the charge inversion of the brushes via charge-image charge interactions. The extent of the transitions for the PSS brushes in the presence of multivalent cations is only slightly influenced by the methanol content.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
Advanced Materials Interfaces
·
2019
·Vol. 6
·期 12
·1900180
·
IF 4.713
Yixin Wang,Yulong Sun,Yanhong Gu,Hongyu Zhang
Natural articular cartilage has excellent superlubrication property, and it is attributed to the hydration lubrication mechanism of the charged biomacromolecules which extend from the cartilage surface to form a brush-like layer. In this study, a bioinspired brush-like polyelectrolyte, namely poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), is grafted onto the SiO 2 wafer and polystyrene (PS) microsphere via surface-initiated polymerization to enhance the lubrication performance. The characterization of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle, and scanning electron microscopy demonstrates that the PMPC polymer brushes are successfully modified onto the substrates. Furthermore, the lubrication test performed using atomic force microscope, with the PMPC-grafted SiO 2 wafer and PMPC-grafted PS microsphere as the contact tribopair, shows that the PMPC-functionalized surfaces significantly reduce friction coefficient under different test conditions. The tenacious water hydration shells formed surrounding the zwitterionic charges of PMPC polymer brushes are responsible for the reduced friction coefficient, which could support high pressures without being squeezed out under loading. In summary, the articular cartilage-inspired surface functionalization method can be used to modify various substrates for enhanced lubrication.
研究领域:
生物材料学
·
摩擦学
✓ 已验证
DOI
高影响因子
Nanomaterials
·
2020
·Vol. 10
·期 4
·799
·
IF 4.324
Qingsong Yang,Li Li,Fang Zhao,Yunwei Wang,Zhishuang Ye,Chen Hua,Zhiyong Liu,Klemen Bohinc,Xuhong Guo
Integrating hollow silica spheres with metal nanoparticles to fabricate multifunctional hybrid materials has attracted increasing attention in catalysis, detection, and drug delivery. Here, we report a simple and general method to prepare hollow silica spheres encapsulating silver nanoparticles (Ag@SiO2) based on spherical polyelectrolyte brushes (SPB), which consist of a polystyrene core and densely grafted poly (acrylic acid) (PAA) chains. SPB were firstly used as nanoreactors to generate silver nanoparticles in situ and then used as sacrificial templates to prepare hybrid hollow silica spheres. The resulted Ag@SiO2composites exhibit high catalytic activity and good reusability for the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. More importantly, this developed approach can be extended to the encapsulation of other metal nanoparticles such as gold nanoparticles into the hollow silica spheres. This work demonstrates that SPB are promising candidates for the preparation of hollow spheres with encapsulated metal nanoparticles and the resulted hybrid spheres show great potential applications in catalysis.Keywords:spherical polyelectrolyte brush;hollow silica;silver nanoparticles;catalyst
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2019
·
IF 3.683
Hongtao Cai,Ran Kou,Guangming Liu
In this work, poly(sodium styrene sulfonate) brushes have been employed as a precursor to prepare thermosensitive strong polyelectrolyte brushes (SPBs) through a counterion exchange strategy. The substitution of hydrophilic Na+ counterions by hydrophobic tetraalkylphosphonium counterions leads to a thermoresponsivity of the SPBs. The thermosensitive properties including hydration, stiffness, and surface water wettability of the SPBs can be modulated by the type of the tetraalkylphosphonium counterions. Nevertheless, the wet thickness of the SPBs with tetraalkylphosphonium counterions does not exhibit an obvious temperature dependency due to the high steric barrier in the crowded environment of SPBs generated by the large tetraalkylphosphonium counterions. The mixtures of small Na+ counterions and large tetraalkylphosphonium counterions are employed to realize the thermosensitive wet thickness without sacrificing other thermoresponsive properties of the SPBs because the mixed counterions can bring both a certain hydrophobicity and some free space to the brushes. This work opens up the opportunities available for the use of counterions to tune the thermosensitivity of SPBs.
研究领域:
材料科学
·
聚合物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 48
·42693-42700
·
IF 3.289
Rui Zhang,Zhenchuan Yu,Yu Cang,Xiaoyan Hou,Zheqi Shen,Jie Deng,Zhiming Zhou,Xuhong Guo,Junwei Wang,Xuedong Zhu
Spherical polyelectrolyte brushes (SPBs), consisting of a poly(styrene) core and poly(acrylic acid) shell densely grafted from the core surface, were synthesized by photoemulsion polymerization. A novel method for highly selective separation of methylene blue (MB) and other dyes is proposed herein, which employs spherical polyelectrolyte brushes as the adsorbent and compressed CO2 as the antisolvent; neither polymer brush nor CO2 on their own can separate the dyes. The SPBs and adsorbed dyes can be precipitated simultaneously from organic solutions by the easy control of CO2 pressure. The effects of several parameters such as CO2 pressure, initial dye concentration and temperature on the removal of MB by PS-PAA have been determined. MB can be selectively adsorbed by PS-PAA from the mixed dye solution with high efficiency, indicating that the binding of MB onto PS-PAA is probably dominated by electrostatic interactions. Due to the Donnan effect of the polymer brush, the adsorbed dyes can be easily eluted by NaCl aqueous solution through ion exchange to obtain the regeneration of the polymer brush, and the recovered PS-PAA retains high adsorption capacity even being regenerated five times. This provides a simple and effective way for the separation of ionic materials, which could be applied in environmental engineering.
研究领域:
环境工程
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2015
·Vol. 3
·期 15
·3745-3751
·
IF 4.696
Yu Cang,Rui Zhang,Guixin Shi,Jianchao Zhang,Lixiao Liu,Xiaoyan Hou,Zhenchuan Yu,Dingye Fang,Xuhong Guo
In this work, we demonstrated a facile and environmentally friendly method of preparing water-soluble cadmium sulfide (CdS) quantum dots (QDs) immobilized in spherical polyelectrolyte brushes (SPBs). The synthesis included three stages as follows: preparation of SPBs, introduction of Cd2+ by the ion-exchange process and in situ fabrication of CdS in SPBs. The X-ray diffraction (XRD) pattern and the transmission electron microscopy (TEM) images proved that the CdS nanocrystallines (NCs) were cubic in structure and well distributed in SPBs. The size and photoluminescence (PL) emission of hybrid nanoparticles (SPB@CdS) could be tailored by adjusting some parameters, such as pH of SPBs, the ratio of Cd/S, the temperature of reaction and dimensions of SPB@CdS. For instance, upon increasing the pH value of SPBs and the ratio of Cd/S, the trap emission of CdS NCs could be transformed into band-edge emission. And the PL emission shifted from 490 to 580 nm as the reaction temperature increased from 10 to 90 °C. More interesting was that the PL emission of SPB@CdS could be quenched and recovered reversibly by pH adjustment due to the pH sensitive chains of poly(acrylic acid) grafting from the polystyrene core. The SPB@CdS displayed excellent photochemical stability in visible light above pH 10 which provided a possibility for storing QDs in visible light. In addition, this simple method can be extended to other sulfide fabrication in SPBs, such as ZnS, which has also been successfully embedded in SPBs.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
CHEMPHYSCHEM
·
2018
·Vol. 19
·期 11
·1404-1413
·
IF 2.947
Ran Kou,Jian Zhang,Zhen Chen,Guangming Liu
Graphical The counterion specificity of polyelectrolyte brushes is determined by specific ion-pairing interactions, modulating the osmotic pressure and hydrophobicity of the brushes. We demonstrate here that the properties of poly (2-(methacryloyloxy) ethyl trimethylammonium chloride) brushes can be tuned by counterion species. When the brushes are exposed to external chloride (Cl − ) counterions, obvious dehydration and collapse are only observed at high salt concentrations. In the presence of very strongly chaotropic perchlorate (ClO 4 − ), the brushes strongly dehydrate and collapse at a very low salt concentration. For the strongly chaotropic thiocyanate ion (SCN − ), the changes in hydration and conformation of the brushes are similar to those observed for ClO 4 − but at a smaller extent at very low salt concentrations. With the addition of kosmotropic acetate (Ac − ), hydration of the brushes increases, accompanied by a swelling of the brushes in the low-salt-concentration regime. In contrast, the brushes dehydrate and collapse with increasing concentration of Ac − in the high-salt-concentration regime. The counterion specificity of the brushes demonstrated here is determined by specific ion-pairing interactions through modulating the osmotic pressure within the brushes and the hydrophobicity of the ion pairs.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SOLID STATE IONICS
·
2017
·
IF 2.354
Jiakui Zhang,Yahua Liu,Zhiqiang Lv,Tongkun Zhao,Ping Li,Yilei Sun,Jingtao Wang
Here, Ti 3 C 2 T x sheets, a representative of MXenes, with lamellar structure and hydrophilic surface are prepared, and then functionalized with sulfonated polyelectrolyte brushes (Ti 3 C 2 T x -SO 3 H) through a facile surface-initiated precipitation-polymerization. The Ti 3 C 2 T x -SO 3 H is then utilized as a new nanofiller to fabricate hybrid proton exchange membrane , where both acidic sulfonated poly (ether ether ketone) (SPEEK) and basic chitosan (CS) are employed as polymer matrixes . The resultant hybrid membranes are systematically characterized and measured including their microstructures, water uptake and proton conduction properties. The results demonstrate that using the sulfonated polyelectrolyte brushes, Ti 3 C 2 T x -SO 3 H sheets construct efficient proton transfer pathways and connect the inherent conduction channels/paths in polymer phase . This significantly enhances the proton conduction of polymer membrane including SPEEK membrane and CS membrane , under both hydrated condition and anhydrous condition. Particularly, the incorporation of 10 wt.% Ti 3 C 2 T x -SO 3 H readily offers 144% and 66% increase in proton conductivity , respectively, to SPEEK membrane and CS membrane under hydrated condition. Furthermore, the hybrid membranes achieve improved thermal and mechanical stabilities. These results herald further advances to preparing functionalized MXenes and their relevant hybrid materials with enhanced performances.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）