15 results on '"Tao Lin"'
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2. Phase Separation Behavior in Tough and Self-Healing Polyampholyte Hydrogels
- Author
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Cui, Kunpeng, Ye, Ya Nan, Sun, Tao Lin, Yu, Chengtao, Li, Xueyu, Kurokawa, Takayuki, and Gong, Jian Ping
- Abstract
Polyampholyte hydrogels (PA gels) are drawing great attention for their excellent mechanical properties including self-healing, high toughness, and fatigue resistance. These mechanical performances are found to be attributed to the hierarchical structure of the PA gels, consisting of reversible ionic bonds at the 1 nm scale, permanent polymer network at the 10 nm scale, and icontinuous phase network at the 100 nm scale. In this work, we systematically studied the phase network formation of these gels aiming to answer the following three questions: (1) how the phase separation occurs? (2) what determines the phase structure? and (3) is this structure in thermodynamic equilibrium or not? Our results show that the phase separation occurs during dialysis of counterions from the gels and it is driven by the Coulombic and hydrophobic interactions. The phase size d0 and the number of aggregated chains in a unit cell of the phase structure n scale with the molecular weight of the partial chain between permanent effective cross-linking Meff as d0 ∼ Meff and n ∼ Meff 2, respectively. A chemical cross-linker and topological entanglement suppress phase separation, while hydrophobic interaction favors phase separation. An intrinsic correlation between the polymer density difference (Δρ) between two phases and d0 is observed (Δρ ∼ d02) as a result of the competition between the driving force to induce phase separation and the resistance to suppress the phase separation. The phase-separated structure is metastable, which is locally trapped by strong intermolecular interactions.
- Published
- 2020
3. Effect of Structure Heterogeneity on Mechanical Performance of Physical Polyampholytes Hydrogels
- Author
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Xueyu Li, Ya Nan Ye, Tasuku Nakajima, Kunpeng Cui, Jian Ping Gong, Tao Lin Sun, Takayuki Kurokawa, Takayuki Nonoyama, and Liang Chen
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,technology, industry, and agriculture ,macromolecular substances ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,complex mixtures ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Chemical engineering ,Self-healing hydrogels ,Materials Chemistry ,0210 nano-technology - Abstract
Recent studies reported a multiscale structure in tough and self-healing hydrogels containing physical associations. For example, a type of tough and self-healing hydrogel from charge-balanced polyampholytes (PA) has a mesoscale bicontinuous double network structure with structural length around 400 nm. This mesoscale network structure plays an essential role in the multistep rupture process, which leads to the high toughness of PA hydrogels. In this work, by using an osmotic stress method, we symmetrically studied how the relative strength of soft and hard networks and the strength of ionic bonds influence the property of PA gels. We found that increasing osmotic stress of the bath solution triggers the structure transition from bicontinuous double network structure to a homogeneous structure, which drives the concurrently opaque−transparent transition in optical property and viscoelastic−glassy transition in mechanical behavior. The gels around the structural transition point were found to possess both high toughness (fracture energy of 7200 J m−2) and high stiffness (Young’s modulus of 12.9 MPa), which is a synergy of soft network and hard network of the bicontinuous structure. Our work not only provides an approach to tune the structure and property of physical hydrogels through tuning physical association but also gives a demo to investigate their relationships, yet another step forward gives inspiration to design a new type of tough and self-healing materials around the structural transition point.
- Published
- 2019
4. Effect of Hydrophobic Side Group on Structural Heterogeneities and Mechanical Performance of Gelatin-Based Hydrogen-Bonded Hydrogel.
- Author
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Zhang, Hui Jie, Wang, Xinyi, Yang, Yuxi, Sun, Tao Lin, Zhang, Aokai, and You, Xiangyu
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- 2022
- Full Text
- View/download PDF
5. Bulk Energy Dissipation Mechanism for the Fracture of Tough and Self-Healing Hydrogels
- Author
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Wei Hong, Tao Lin Sun, Kunpeng Cui, Feng Luo, Daniel R. King, Tasuku Nakajima, Hui Jie Zhang, Yiwan Huang, Takayuki Kurokawa, and Jian Ping Gong
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Quantitative Biology::Biomolecules ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Thermodynamics ,Fracture mechanics ,02 engineering and technology ,Dissipation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Viscoelasticity ,0104 chemical sciences ,Inorganic Chemistry ,Hysteresis ,Rheology ,Self-healing hydrogels ,Materials Chemistry ,Fracture (geology) ,Deformation (engineering) ,0210 nano-technology - Abstract
Recently, many tough and self-healing hydrogels have been developed based on physical bonds as reversible sacrificial bonds. As breaking and re-forming of physical bonds are time-dependent, these hydrogels are viscoelastic and the deformation rate and temperature pronouncedly influence their fracture behavior. Using a polyampholyte hydrogel as a model system, we observed that the time–temperature superposition principle is obeyed not only for the small strain rheology but also for the large strain hysteresis energy dissipation and the fracture energy below a certain temperature. The three processes possess the same shift factors that obey the equation of Williams, Landel, and Ferry (WLF) time–temperature equivalence. The fracture energy Γ scales with the crack velocity Vc over a wide velocity range as Γ ∼ Vcα (α = 0.21). The exponent α of the power law is well-related to the exponent κ of the relaxation modulus G(t) ∼ t–κ (κ = 0.26), obeying the prediction α = κ/(1 + κ) from classic viscoelasticity theory. These results show that the fracture energy of the polyampholyte gel is dominated by the bulk viscoelastic energy dissipated around the crack tip. This investigation gives an insight into designing tough and self-healing hydrogels and predicting their fracture behaviors from their dynamic mechanical spectrum.
- Published
- 2017
6. Effect of Structure Heterogeneity on Mechanical Performance of Physical Polyampholytes Hydrogels.
- Author
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Cui, Kunpeng, Ye, Ya Nan, Sun, Tao Lin, Chen, Liang, Li, Xueyu, Kurokawa, Takayuki, Nakajima, Tasuku, Nonoyama, Takayuki, and Gong, Jian Ping
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- 2019
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7. Elastic–Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate.
- Author
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Shi, Ran, Sun, Tao Lin, Luo, Feng, Nakajima, Tasuku, Kurokawa, Takayuki, Bin, Yue Zhen, Rubinstein, Michael, and Gong, Jian Ping
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- 2018
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8. nBulk Energy Dissipation Mechanism for the Fracture of Tough and Self-Healing Hydrogels.
- Author
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Tao Lin Sun, Feng Luo, Wei Hong, Kunpeng Cui, Yiwan Huang, Hui Jie Zhang, King, Daniel R., Takayuki Kurokawa, Tasuku Nakajima, and Jian Ping Gong
- Subjects
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ENERGY dissipation , *SELF-healing materials , *HYDROGELS - Abstract
Recently, many tough and self-healing hydrogels have been developed based on physical bonds as reversible sacrificial bonds. As breaking and re-forming of physical bonds are time-dependent, these hydrogels are viscoelastic and the deformation rate and temperature pronouncedly influence their fracture behavior. Using a polyampholyte hydrogel as a model system, we observed that the time-temperature superposition principle is obeyed not only for the small strain rheology but also for the large strain hysteresis energy dissipation and the fracture energy below a certain temperature. The three processes possess the same shift factors that obey the equation of Williams, Landel, and Ferry (WLF) time-temperature equivalence. The fracture energy Γ scales with the crack velocity Vc over a wide velocity range as Γ ~ Vc α (α = 0.21). The exponent α of the power law is well-related to the exponent κ of the relaxation modulus G (t) ~ t-κ (κ = 0.26), obeying the prediction α = κ/(1 + κ) from classic viscoelasticity theory. These results show that the fracture energy of the polyampholyte gel is dominated by the bulk viscoelastic energy dissipated around the crack tip. This investigation gives an insight into designing tough and self-healing hydrogels and predicting their fracture behaviors from their dynamic mechanical spectrum. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
9. Creep Behavior and Delayed Fracture of Tough Polyampholyte Hydrogels by Tensile Test.
- Author
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Karobi, Sadia Nazneen, Tao Lin Sun, Takayuki Kurokawa, Feng Luo, Tasuku Nakajima, Takayuki Nonoyama, and Jian Ping Gong
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POLYAMPHOLYTES , *CREEP (Materials) , *HYDROGELS , *FRACTURE toughness , *TENSILE tests , *SELF-healing materials - Abstract
Polyampholyte (PA) hydrogels are a new class of tough and self-healing supramolecular hydrogels that have a potential as load-bearing soft materials. Studying on the creep behavior of these hydrogels and understanding the molecular mechanism are important for prediction of lifetime of the materials. In the present work, we study the creep rupture dynamics of the PA hydrogels with and without chemical cross-linking, in a certain observation time window. We have found that above some critical loading stress both physical and lightly chemically cross-linked hydrogels undergo creep rupture while moderately chemically cross-linked hydrogel resists creep flow. To elucidate the molecular mechanism, we have further compared the creep behaviors of the physical and lightly chemically cross-linked samples. The creep rate of the samples decreases with the creep time, following a power law relation, regardless of the loading stress variation. The fracture time of both of these hydrogels exponentially decreases with the increase of the loading stress, following the same master curve at high loading stress region, while the behavior of the two samples becomes different in the low loading stress region. We have explained the delayed fracture dynamics at high loading stress region in terms of a relatively weak strong bond rupture mechanism. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
10. Self-Healing Behaviors of Tough Polyampholyte Hydrogels.
- Author
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Ihsan, Abu Bin, Tao Lin Sun, Takayuki Kurokawa, Karobi, Sadia Nazneen, Tasuku Nakajima, Takayuki Nonoyama, Roy, Chanchal Kumar, Feng Luo, and Jian Ping Gong
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POLYAMPHOLYTES , *HYDROGELS , *SELF-healing materials , *IONIC bonds , *TEMPERATURE effect , *CHEMICAL structure - Abstract
Recently, polyampolytes have been discovered to form hydrogels that possess high toughness, full resilience, and self-healing between two cut surfaces. The self-healing of this class of hydrogels is based on the re-forming of the multiple ionic bonds at the fractured surfaces, in which the mobility of the polymer segments and strength of the ionic bonds play an important role. In this work, we study the effects of healing temperature and chemistry of the polyampholyte hydrogels (chemical cross-linker density and chemical structure of the monomers) on the healing kinetics and healing efficiency. The high healing temperature substantially accelerates the self-healing kinetics. Chemical cross-linking reduces the self-healing efficiency. Monomers with more hydrophobic feature give a low self-healing efficiency. For polyampholyte physical hydrogels with a softening temperature below the room temperature, excellent healing efficiency (∼84% on average and maximum 99%) was observed without any external stimuli. We found a correlation between the self-healing efficiency and the fraction of dynamic bonds in the total bonds for relatively soft samples, which is an evidence that the self-healing is due to the re-forming of dynamic bonds. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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11. Strong and Tough Polyion-Complex Hydrogels from Oppositely Charged Polyelectrolytes: A Comparative Study with Polyampholyte Hydrogels.
- Author
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Feng Luo, Tao Lin Sun, Tasuku Nakajima, King, Daniel R., Takayuki Kurokawa, Yu Zhao, Abu Bin Ihsan, Xufeng Li, Honglei Guo, and Jian Ping Gong
- Subjects
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POLYIONS , *POLYELECTROLYTES , *HYDROGELS , *IONIC bonds , *COPOLYMERIZATION - Abstract
Oppositely charged homopolyelectrolytes were found to form strong, tough, and self-healing polyion-complex (PIC) hydrogels, similar to polyampholytes (PA) which have opposite charges randomly distributed on the same polymer chains. The excellent mechanical performances of these two novel hydrogels are the results of dynamic ionic bonds formation between entangled polymer chains. For the PIC system, only interchain bonding occurs, while for the PA system both inter- and intrachain bonding exist. In addition, the ion pairs are expected to form stronger bonding in the PIC system than those in the PA system. In this work, we performed a comparative study of PIC hydrogels with the PA hydrogels. The PIC hydrogels are synthesized by sequential homopolymerization of cationic and anionic monomers at varied formulation, and their swelling and mechanical properties are systematically studied in comparison to the PA hydrogels that were synthesized from random copolymerization of anionic monomers and cationic monomers of the similar formulation. Different from the PA system which only forms tough hydrogels around zero net charge composition without chemical cross-linking, the PIC system forms tough physical hydrogels even at weakly off-balanced charge composition. At the charge-balanced composition, the low entanglement concentration of homocharged polyelectrolyte chains leads to tough PIC hydrogels formation at much lower concentrations than that of PA hydrogels. As a result, the PIC hydrogels are much tougher than the PA hydrogels prepared at the same monomer composition. In similar to PA hydrogels, the PIC hydrogels also exhibit broad dynamic mechanical spectra, indicating the formation of ion complexes with widely ranged bond strength. The PIC hydrogels have strong viscoelasticity in comparison with PA hydrogels. However, the two systems show the similar activation energies of the dynamic mechanical spectra. The SEM microstructural observation shows that the PIC hydrogels have segregated structure while PA hydrogels are more homogeneous. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
12. Crack Blunting and Advancing Behaviors of Tough andSelf-healing Polyampholyte Hydrogel.
- Author
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Feng Luo, Tao Lin Sun, Tasuku Nakajima, Takayuki Kurokawa, Yu Zhao, Abu Bin Ihsan, Hong Lei Guo, Xu Feng Li, and Jian Ping Gong
- Subjects
- *
POLYAMPHOLYTES , *HYDROGELS , *FREE radicals , *COPOLYMERIZATION , *IONIC bonds , *BOND strengths , *VISCOELASTICITY - Abstract
Recently, we have reported that polyampholytes,synthesized fromfree radical copolymerization of anionic monomer and cationic monomer,form physical hydrogels of high toughness and self-healing. The randomdistribution of the opposite charges forms ionic bonds of a wide distributionof strength. The strong bonds serve as permanent cross-links, impartingelasticity, whereas the weak bonds serves as reversible sacrificialbonds by breaking and reforming to dissipate energy. In this work,we focus on the rupture behaviors of the polyampholyte physical hydrogel,P(NaSS-co-MPTC), copolymerized from sodium p-styrenesulfonate (NaSS) and 3-(methacryloylamino)propyltrimethylammoniumchloride (MPTC). Tensile test and pure shear test were performed atvarious stretch rates in the viscoelastic responses region of thematerial. Tensile test showed yielding, strain softening, and strainhardening, revealing the dually cross-linked feature of the gel. Pureshear test showed crack blunting at the notched tip and a large yieldingzone with butterfly shaped birefringence pattern ahead of the cracktip. After blunting, crack advanced at steady-state velocity witha constant angle. The conditions for the occurrence of crack bluntingand variables governing the crack advancing angle are discussed. Wefound that even for these highly stretchable samples, significantblunting only occurs when the tensile fracture stress Ïfis larger than modulus Eby a factor of about 2, in consistent with Huiâs theoreticalprediction for elastic materials. The crack advancing angle θwas found to be proportional to Ïy/Eover a wide stretch rate range, where Ïyis the yielding stress. In addition, thefracture energy was correlated to small strain modulus by a powerlaw in the viscoelastic response region. This systematic study willmerit revealing the fracture mechanism of tough viscoelastic materialsincluding biological tissues and recently developed tough and highlystretchable hydrogels. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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13. Supramolecular Assemblies of a Semirigid Polyanionin Aqueous Solutions.
- Author
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Wu, Zi Liang, Arifuzzaman, Md., Kurokawa, Takayuki, Le, Khoa, Hu, Jian, Sun, Tao Lin, Furukawa, Hidemitsu, Masunaga, Hiroyasu, and Gong, Jian Ping
- Published
- 2013
- Full Text
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14. High Fracture Efficiency and Stress ConcentrationPhenomenon for Microgel-Reinforced Hydrogels Based on Double-NetworkPrinciple.
- Author
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Hu, Jian, Kurokawa, Takayuki, Nakajima, Tasuku, Sun, Tao Lin, Suekama, Tiffany, Wu, Zi Liang, Liang, Song Miao, and Gong, Jian Ping
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- 2012
- Full Text
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15. Phase Behavior in Self-Assembly of Inorganic/Poly(4-vinylpyridine)-b-poly(ε-caprolactone) Hybrid.
- Author
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Tao Lin, Rong-Ming Ho, and Jia-Chong Ho
- Subjects
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MOLECULAR self-assembly , *INORGANIC compounds , *DIBLOCK copolymers , *NANOSTRUCTURED materials , *TRANSMISSION electron microscopy , *SMALL-angle X-ray scattering , *PHASE transitions , *SEPARATION (Technology) - Abstract
A series of poly(4-vinylpyridine)-b-poly(ε-caprolactone) (P4VP-PCL) diblock copolymers of different composition (namely, various nanostructured phases) were synthesized for hybridization with gold precursors. Interesting phase behavior of gold precursors/P4VP-PCL hybrids was found as evidenced by transmission electron microscopy and small-angle X-ray scattering (SAXS). Consistent with theoretical prediction, phase transformation in the hybrids with PCL-rich P4VP-PCL can be induced by the introduction of the gold precursors. In particular, the phase transformation can be achieved by introducing a very small amount of the gold precursors because of the significant increase in the effective excluded volume of hybridized P4VP microdomain as identified by SAXS experiments through the analysis of the 1D correlation function. This morphological evolution is referred to as the bridging mechanism, suggesting that the PCL block of the P4VP-PCL in the hybrids might play an important role in blocking the interconnection between hybridized P4VP microdomains. In contrast, disordered morphology was observed in the hybrids with P4VP-rich P4VP-PCL because of the strong association between the gold precursors and the P4VP block that might disrupt the ordered phase from microphase separation. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
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