Jiang Zhao

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Name: 赵江; Jiang Zhao

Organization: Institute of Chemistry, Chinese Academy of Sciences , China

Department: Institute of Chemistry

Title: Researcher/Professor(PhD)

TOPICS

Polymer

Polyelectrolyte

Chemicals
References

Retarded local dynamics of single fluorescent probes in polymeric glass due to interaction strengthening

Co-reporter:Hao Zhang, Desheng Li, Kui Wu, Fuyi Wang, Jingfa Yang, Jiang Zhao

Polymer 2017 Volume 116(Volume 116) pp:

Publication Date(Web):5 May 2017

DOI:10.1016/j.polymer.2017.01.002

•Rotation of single fluorescent probes doped in polymer matrix was visualized.•Vibration modes of local dynamics was discovered by power spectra of rotation trajectory.•Local dynamics detected by the probes is retarded by introduction of hydrogen bonding between the probe and the matrix.The effect of strengthening of interaction between single fluorescent probes and polymer matrix to the probes' dynamics is investigated using single molecule fluorescence defocus microscopy. By introducing multiple hydroxyl groups to the fluorescent probes (perylene diimide derivatives) which builds up hydrogen bonds between the probe and polymer matrix, the dynamics is discovered to be retarded. This is evidenced by the lowering of the frequency of the vibrational modes in the power spectra of the rotation trajectories of individual fluorescent probes, and also by the decrease in population of rotating probes. The results show that by strengthening the probe-matrix interaction, the local dynamics detected by the probes is equivalent to that detected by a bigger probe, due to the enhanced friction between the probe and the polymer matrix.Download high-res image (201KB)Download full-size image

Detection of site-dependent segmental mobility of polymer by fluorescent defocused imaging

Co-reporter:De-sheng Li;Jing-fa Yang 赵江

Chinese Journal of Polymer Science 2017 Volume 35( Issue 12) pp:1488-1496

Publication Date(Web):18 August 2017

DOI:10.1007/s10118-017-1976-8

Polymer chain ends play an important role in the glassy dynamics of polymeric materials. In this study, a combination of single molecule defocus fluorescence microscopy and well-controlled atom transfer radical polymerization was used to investigate site-dependent segmental mobility of poly(n-butyl methacrylate). As the temperature increased, the rotation of fluorophores, which were selectively labelled in chain end and chain middle, was gradually activated. The power spectra of rotation trajectories, the distribution of angular displacement as well as the population of rotating fluorophores demonstrated that the local dynamics was more activated at the chain ends than the middles, showing the unique contribution of the chain end to the dynamics of the system.

Photo-controllable coil-to-globule transition of single polymer molecules

Co-reporter:Yu Shi, Jingfa Yang, Jiang Zhao, Haruhisa Akiyama, Masaru Yoshida

Polymer 2016 Volume 97() pp:309-313

Publication Date(Web):5 August 2016

DOI:10.1016/j.polymer.2016.05.036

•The coil-to-globule conformation transition of PNIPAM is studied at single molecular level.•Isomerization of the azobenzene moiety at the chain end of PNIPAM changes the polarity of the end.•The temperature for conformation transition of PNIPAM is shifted up to 12 °C with UV irradiation.This study demonstrates that the conformation transition of single polymer molecules can be adjustable by applying external irradiation. By choosing poly N-isopropylacrylamide as the model system, its coil-to-globule conformation transition temperature is shifted with application of external UV irradiation, due to the photo-isomerization of the azobenzene moiety attached to the chain end. The investigation was conducted at single molecular level by fluorescence correlation spectroscopy, using hydrodynamic radius as the measure of chain dimension. It is discovered that the coil-to-globule transition temperature of the PNIPAM-azo can be controlled up to a difference of 12 °C upon external irradiation, due to the difference in polarity of the azobenzene end group.

When does a diblock copolymer probe the interfacial rheological effect?

Co-reporter:Jingfa Yang

Science China Chemistry 2016 Volume 59( Issue 10) pp:1330-1334

Publication Date(Web):2016 October

DOI:10.1007/s11426-016-0181-8

Lateral diffusion of diblock copolymer residing on the interfaces between two immiscible liquids is investigated at single molecular level. Fluorescence correlation spectroscopy was used to study the diffusion of fluorescence-labeled diblock copolymer, polystyrene-b-polyisoprene, at the interface formed between two immiscible liquids. The interfaces are formed between N,N-dimethylformamide (DMF) and a few immiscible liquids, n-alkane and polyisoprene. Interfacial diffusion coefficient of the diblock copolymer probe is found to decrease monotonously with the increase of the molecular length of the interface constituting liquids. The decrease of diffusion coefficient follows the prediction by Einstein relation using the viscosity of the constituting liquids as the variables only for interfaces between DMF and very small n-alkanes. For interfaces formed between DMF and bigger alkanes and especially between DMF and polyisoprene, the diffusion coefficient is much higher than the calculated value, indicating that the probe molecule starts to probe the much less viscous interfacial region because the interfacial width gets larger, whose thickness is comparable to the molecule size of the liquids.

The growth of filaments under macromolecular confinement using scaling theory

Co-reporter:Lin Zhu, Wei Pan, Xi Lu, Desheng Li, Jiang Zhao and Dehai Liang

Chemical Communications 2015 vol. 51(Issue 88) pp:15928-15931

Publication Date(Web):04 Sep 2015

DOI:10.1039/C5CC06748K

Quantitatively describing macromolecular confinement is still a challenge. Using the assembly of DNA tiles in a polyacrylamide network as a model, we studied the effect of macromolecular confinement on the growth of the filament by scaling theory. The results show that the confinement regulates the morphology, the initial growth rate v, and the eventual length of the filament Nm. The initial growth rate is dependent on the medium viscosity η as ν ∝ η−0.94, and the filament adjusts its length in the given confined space as Nm ∝ (ξ/Rg)1.8, with ξ being the mesh size of the polyacrylamide solution and Rg being the radius of gyration of polyacrylamide.

Understanding anti-polyelectrolyte behavior of a well-defined polyzwitterion at the single-chain level

Co-reporter:Fei Wang;Jingfa Yang

Polymer International 2015 Volume 64( Issue 8) pp:999-1005

Publication Date(Web):

DOI:10.1002/pi.4907

Abstract

A study was made of the anti-polyelectrolyte effect of a model polyzwitterion at the single-chain level and from the point of view of comparison with inorganic salts and organic inner salts. A well-defined polymer of sulfobetaine was synthesized and fluorescently labeled. Fluorescence correlation spectroscopy was adopted to probe diffusion and chain size of polyzwitterion single chains in extremely dilute aqueous solutions over a broad concentration range of added salts. By the introduction of inorganic salts and organic inner salts, the single chains of polyzwitterions expanded with an increase of salt concentration. This observation indicates that the break-up of the dipole–dipole attraction between the zwitterion units is the mechanism of the anti-polyelectrolyte effect of polyzwitterions. The difference in the strength of the anti-polyelectrolyte effect induced by inorganic salts and organic inner salts also indicates the partial contribution from the asymmetric adsorption of ions onto polyzwitterion chains. © 2015 Society of Chemical Industry

Axial Growth and Fusion of Liposome Regulated by Macromolecular Crowding and Confinement

Co-reporter:Yun Liu, Lin Zhu, Jingfa Yang, Jianbo Sun, Jiang Zhao, and Dehai Liang

Langmuir 2015 Volume 31(Issue 17) pp:4822-4826

Publication Date(Web):April 15, 2015

DOI:10.1021/la504699y

The endomembrane system, including the endoplasmic reticulum, Golgi apparatus, lysosomes, and endosomes, is located in the crowded intracellular environment. An understanding of the cellular structure and functions requires knowledge of how macromolecular crowding and confinement affect the activity of membrane and its proteins. Using negatively charged liposome and the peptide K3L8K3 as a model system, we studied the aggregation behavior of liposome in a matrix of polyacrylamide and hyaluronic acid. Without matrix, the liposomes form spherical aggregates in the presence of K3L8K3. However, they orient in one dimension and fuse into a tube up to 40 μm long in the matrix. The growth of the tube is via end-to-end connection. This anisotropic growth is mainly due to the macromolecular confinement provided by the polymer network. The study of the interactions between liposome and peptide in the crowded environment helps to reveal the mechanism of membrane-related processes in vivo.

Swelling enhancement of polyelectrolyte brushes induced by external ions

Co-reporter:Xiao Chu, Jingfa Yang, Guangming Liu and Jiang Zhao

Soft Matter 2014 vol. 10(Issue 30) pp:5568-5578

Publication Date(Web):30 May 2014

DOI:10.1039/C4SM00860J

It has been observed previously that when permanently charged polyelectrolyte brushes are exposed to an external salt solution, they shrink when the salt level is high enough. In this study, we observed an enhanced swelling process before the salt concentration reached that limit. We systematically investigated a few strong polyelectrolyte brush systems, including sodium polystyrene sulfonate (PSSNa), poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (PMETAC) and potassium poly(3-sulfopropyl methacrylate) (PSPMA) with different molecular weights and grafting density using a combination of methods, including ellipsometry, quartz crystal microbalance with dissipation (QCM-D) and atomic force microscope (AFM). The swelling enhancement is expressed by the thickening of the brush layer at moderate salt concentrations, accompanied by the decrease of refractive index, the increase of the amount of solvent inside the brushes and an increase in retardation time. A scenario is proposed in which the counterions penetrate into the brushes driven by the external salt ions, they disrupt and break up the previously formed multiplets due to the dipole–dipole interaction by the ion-pairs on the polymer chain. This process results in the release of the bound segments and the stretching of the polymer chains.

Segmental dynamics near the chain end of polystyrene in its ultrathin films: A study by single-molecule fluorescence de-focus microscopy

Co-reporter:ZhongLi Zheng;DeSheng Li;JingFa Yang

Science China Chemistry 2014 Volume 57( Issue 3) pp:389-396

Publication Date(Web):2014 March

DOI:10.1007/s11426-013-5054-y

Rotational motion of fluorophores chemically attached to polystyrene chain-ends in ultra-thin films on solid substrates was studied by single-molecule fluorescence de-focus microscopy. The collective feature of the rotational motion was found and evidenced by the sharp change of the population of fluorophores undergoing rotational motion within a very narrow temperature range (named as the changing temperature, Tc). The Tc value was found to depend on film thickness and interfacial chemistry and the variation of the Tc value is also dependent on the molecular weight of the polymer. The results demonstrate that the spatial confinement effect enhances the segmental mobility near the polymer chain-ends while the interfacial attraction restricts the segmental motion inside the thin film.

Resolving the Difference in Electric Potential within a Charged Macromolecule

Co-reporter:Shuangjiang Luo, Xiubo Jiang, Lei Zou, Fei Wang, Jingfa Yang, Yongming Chen, and Jiang Zhao

Macromolecules 2013 Volume 46(Issue 8) pp:

Publication Date(Web):April 4, 2013

DOI:10.1021/ma302276b

The difference of the electric potential between the middle and end of polystyrenesulfonate (PSS–) chain is discovered experimentally. Using a pH-responsive fluorophore attached to these two locations on the PSS– chain, the local pH value was determined by single molecule fluorescence technique: photon counting histogram (PCH). By the observation of a very high accumulation of proton (2–3 orders of magnitude in concentration) at the vicinity of the PSS– as a result of the electrostatic attraction between the charged chain and protons, the electric potential of the PSS– chain is determined. A higher extent of counterion adsorption is discovered at the middle of the PSS– chain than the chain end. The entropy effect of the counterion adsorption is also discovered—upon the dilution of protons, previously adsorbed counterions are detached from the chain.

Advantage of Fluorescence Correlation Spectroscopy for the Study of Polyelectrolytes

Co-reporter:Pengxiang Jia;Yongkuan Gong;Shengqin Wang

Chinese Journal of Chemistry 2012 Volume 30( Issue 9) pp:2237-2240

Publication Date(Web):

DOI:10.1002/cjoc.201200596

Abstract

The advantage of fluorescence correlation spectroscopy to study single chain behavior of polyelectrolytes has been demonstrated by checking the coil-to-globule transition of poly 2-vinylpyridine with the change of pH value in aqueous solution. The ultra-high sensitivity of FCS allows measurement at extreme dilution where the effect of electrostatic interaction between the chains is greatly suppressed. The results exposed first-order conformation transition of P2VP as detected by FCS while inter-chain aggregation occurred in the experiments of dynamic light scattering.

Conformational Transition of Poly(N-isopropylacrylamide) Single Chains in Its Cononsolvency Process: A Study by Fluorescence Correlation Spectroscopy and Scaling Analysis

Co-reporter:Fei Wang, Yi Shi, Shuangjiang Luo, Yongming Chen, and Jiang Zhao

Macromolecules 2012 Volume 45(Issue 22) pp:9196-9204

Publication Date(Web):November 8, 2012

DOI:10.1021/ma301780f

Fluorescence correlation spectroscopy (FCS) has been adopted to investigate the conformational transition of poly(N-isopropylacrylamide) (PNIPAM) single chains with moderate molecular weights in the cononsolvency process. A practical approach of performing accurate FCS measurements with the presence of the refractive index mismatch was developed. The practical and reliable FCS calibration facilitates the acquisition of the hydrodynamic radius (RH) of PNIPAM single chains with the change of the water–ethanol composition. By using the synthesized PNIPAM samples covering a range of degrees of polymerization (N), the scaling analysis in the relationship of RH ∼ Nν exhibits a progressive, re-entrant change of the scaling index (ν) between good solvent (0.57) and poor solvent (∼1/3) condition, which is a reflection of a re-entrant conformational transition of the polymers. Furthermore, the highly asymmetrical feature of the cononsolvency process of single PNIPAM chains was unveiled, which indicates a much stronger effect or interaction of the ethanol molecules to the PNIPAM chain. Comparisons of the present results with previous reports provided new information to the mechanism model of the PNIPAM cononsolvency.

Diffusion of Ionic Fluorescent Probes atop Polyelectrolyte Brushes

Co-reporter:Cunfu Zhang, Xiao Chu, Zhongli Zheng, Pengxiang Jia, and Jiang Zhao

The Journal of Physical Chemistry B 2011 Volume 115(Issue 51) pp:15167-15173

Publication Date(Web):November 14, 2011

DOI:10.1021/jp204612u

The lateral diffusion of ionic fluorescent molecules atop polyelectrolyte brushes was adopted to probe the distribution of counterions of the polyelectrolyte brushes. With a combination of single molecule fluorescence techniques, fluorescence correlation spectroscopy and single molecule fluorescence imaging, the lateral diffusion of the ionic probes (sulforhodamine B, rhodamine 6G) at the top of the model polyelectrolyte brushes with the opposite charges, poly([2-(methylacryloyloxyl)ethyl] trimethylammonium chloride) (PMETAC) and polystyrene sulfonate (PSS), was studied with different external salt concentrations. A huge decrease of the diffusion rate of the probes was observed at salt concentrations 2–3 orders of magnitude lower than that for any detectable change of brushes thickness could be observed. The results reflect the early collapse of the top portion of the polyelectrolyte brushes and also the penetration of the probes into the brushes due to the increase of osmotic pressure by the salt level in the solution. The diffusion of the fluorescent counterion can serve as a very sensitive probe of the structure atop the polyelectrolyte brushes.

Hofmeister Effect on the Interfacial Dynamics of Single Polymer Molecules

Co-reporter:Qingbo Yang and Jiang Zhao

Langmuir 2011 Volume 27(Issue 19) pp:11757-11760

Publication Date(Web):August 30, 2011

DOI:10.1021/la202510d

The Hofmeister effect on interfacial dynamics has been discovered for single charged polymer molecules (sodium polystyrene sulfonate) adsorbed on a hydrophobic surface from an aqueous solution. The presence of ions in the aqueous solution affects the surface diffusivity, and its amplitudes and the surface friction follow the Hofmeister series—the kosmotropic ions slowed down the surface diffusivity and the chaotropic ions speeded it up. The amplitude of the surface friction exhibits a good correlation with the surface tension increment, indicating the interfacial feature of the Hofmeister effect.

Single Chain Diffusion of Poly(ethylene oxide) in Its Monolayers before and after Crystallization

Co-reporter:Rui Chen, Lin Li and Jiang Zhao

Langmuir 2010 Volume 26(Issue 8) pp:5951-5956

Publication Date(Web):December 29, 2009

DOI:10.1021/la903897v

Lateral diffusion of single chain related to the crystallization process of poly(ethylene oxide) (PEO) in its monolayers on silica surfaces is studied by single molecule fluorescence microscopy and single molecule tracking techniques. Diffusion of PEO chains is observed in the supercooled state before crystallization as well as in the noncrystalline regions after crystallization. In the postcrystallization monolayers, the diffusion coefficient of PEO chains is an order of magnitude lower than that in the supercooled state before crystallization. The origin is attributed to the change of polymer surface concentration due to the consumption of polymer molecules in the crystal formation. This is supported by the results showing a monotonous decrease of diffusion coefficient with the thickness decrease of the monolayer in its supercooled state. The PEO chains take a more flattened conformation under lower surface concentration and stick stronger to the surface. As a consequence, the diffusion rate is reduced. The results clearly demonstrate a strong mutual effect between the crystallization process and the mass transportation for the polymer crystallization under surface confinement.

Water-Swelling-Induced Morphological Instability of a Supported Polymethyl Methacrylate Thin Film

Co-reporter:Benxin Jing and Jiang Zhao, Yan Wang, Xin Yi and Huiling Duan

Langmuir 2010 Volume 26(Issue 11) pp:7651-7655

Publication Date(Web):May 5, 2010

DOI:10.1021/la1004566

The instability of supported poly(methyl methacrylate) (PMMA) thin films in water has been investigated. It is found that PMMA films partially detach from the solid substrate, resulting in the formation of bubbles under water. The process is reversible. Surface morphology analysis shows that the radius of curvature of the bubbles is dependent on the thickness of the PMMA films and is independent of the treatment of the films, such as the annealing temperature and the annealing time. Theoretical analysis based on a two-layer model (the swollen layer and the interior layer) shows that the partial swelling of PMMA in water is the physical origin of bubble formation.

Direct Observation of Rotational Motion of Fluorophores Chemically Attached to Polystyrene in Its Thin Films

Co-reporter:Zhongli Zheng, Fangying Kuang and Jiang Zhao

Macromolecules 2010 Volume 43(Issue 7) pp:3165-3168

Publication Date(Web):March 17, 2010

DOI:10.1021/ma902569n

Thickness Dependence of Liquid−Liquid Phase Separation in Thin Films of a Polyolefin Blend

Co-reporter:Song Hong, Xiaohua Zhang, Ruoyu Zhang, Jiang Zhao and Charles C. Han

Macromolecules 2009 Volume 42(Issue 12) pp:4349-4351

Publication Date(Web):May 6, 2009

DOI:10.1021/ma802676f

Mobility of single DNA chain under electric field during its transient contact with solid surfaces

Co-reporter:Benxin Jing;Qingbo Yang;Yingxi Zhu

Journal of Polymer Science Part B: Polymer Physics 2009 Volume 47( Issue 24) pp:2541-2546

Publication Date(Web):

DOI:10.1002/polb.21880

Abstract

The motion of DNA chain under electric field when it is in transient contact with the solid surfaces in aqueous solution was studied by single molecule fluorescence microscopy at the total internal reflection geometry (TIRFM). In situ observation discovered that single λ-DNA chains driven by electric field made transient contact with the solid surface and made hitting–sliding–leaving-like motion along the surface. By varying the surface chemistry, from the negative-charged silanol group-rich surface to positive-charged amino group-rich surface, as well as hydrophobic surfaces, the dependence of DNA mobility on the surface–DNA interaction was studied. The results show that a dependence of the mobility of DNA on the surface polarity with respect to DNA itself. The study on different surfaces rich of silanol, amide, amino, and methyl groups show a sequence of DNA mobility of silanol > amide > amino. The mobility of DNA on methyl terminated surface was found to be similar to that on amino surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2541–2546, 2009

Liquid–Liquid Phase Separation and Crystallization in Thin Films of a Polyolefin Blend

Co-reporter:Song Hong, Xiaohua Zhang, Ruoyu Zhang, Li Wang, Jiang Zhao and Charles C. Han

Macromolecules 2008 Volume 41(Issue 7) pp:2311-2314

Publication Date(Web):March 12, 2008

DOI:10.1021/ma7025379

Lateral Mobility of Single Chains at a Liquid Polymer Interface

Co-reporter:Jingfa Yang, Jiang Zhao and Charles C. Han

Macromolecules 2008 Volume 41(Issue 20) pp:7284-7286

Publication Date(Web):October 2, 2008

DOI:10.1021/ma8015135

Study of the Morphology of the Three-Phase Contact Line and Its Evolution by Morphological Examination after Droplet Evaporation of Aqueous Polymer Solutions

Co-reporter:Gang Liu, Cunfu Zhang, Jiang Zhao and Yingxi Zhu

Langmuir 2008 Volume 24(Issue 15) pp:7923-7930

Publication Date(Web):June 27, 2008

DOI:10.1021/la800452w

The local morphology and its evolution of an air−liquid−solid three-phase contact line was studied on the homogeneous surfaces of homopolymer of polystyrene (PS) and poly(methyl methacrylate) (PMMA) and the nanostructured surface of diblock copolymer of PS-b-PMMA by the approach of the morphological study of the residual solid after droplet evaporation of water-soluble polymers such as poly(vinylpyrrolidone) (PVP) and poly(acrylic acid). The observation by atomic force microscopy discovered the stripelike “button-and-ribbon” structure of the precipitated polymer solute along the moving direction of the contact line. On the surface of PS-b-PMMA, the morphology of PVP has a close correlation with the nanostructure of PS-b-PMMA. The results exhibit the local morphology of the contact line and its evolution, revealing its pinning and depinning processes on the nanometer scale.

The growth of filaments under macromolecular confinement using scaling theory

Co-reporter:Lin Zhu, Wei Pan, Xi Lu, Desheng Li, Jiang Zhao and Dehai Liang

Chemical Communications 2015 - vol. 51(Issue 88) pp:NaN15931-15931

Publication Date(Web):2015/09/04

DOI:10.1039/C5CC06748K