Polyampholyte gels,which have hierarchical structures,exhibit excellent self-healing properties and have great promise for biomaterials and bioengineering.We investigated the relationship between microscopic structure...Polyampholyte gels,which have hierarchical structures,exhibit excellent self-healing properties and have great promise for biomaterials and bioengineering.We investigated the relationship between microscopic structures and macroscopic viscoelastic properties of polyampholyte gels and found three factors influencing their viscoelastic properties,including the chemical crosslinking bonds,topological entanglements controlled by monomer concentration,and the ionic bonds.Ionic strength plays a major role on the strength of ionic bonds.A crossover point of elastic modulus and loss modulus was observed in the dynamic frequency sweeps at low monomer concentration or low chemical crosslinking density for gels with intermediate strength of ionic bonds.The solid-liquid transition signaled by the crossover point is a typical feature of dynamic associated gels,representing the dynamical association-dissociation of the ionic bonds and full relaxation of the topological entanglements in the gel network.While the crossover point disappears when the ionic bonds are too weak or too strong to form“permanent”bonds.Consistently,in the non-linear yielding measurement,gels with intermediate strength of the ionic bonds are ductile and yield at very large shear strain due to the self-healing properties and the dynamic association-dissociation of the ionic bonds.But the self-healing properties disappear when the ionic bond strength is too weak or too strong.Our work reveals the mechanism of how the dynamic association-dissociation of ionic bonds influences both the linear and non-linear viscoelastic properties of the polyampholyte gels.展开更多
The significant role of the polyelectrolytic nature of non-collagenous proteins (NCPs) in regulating the in vivo mineralization of collagen provides important insights for scientists searching for analogues of NCPs to...The significant role of the polyelectrolytic nature of non-collagenous proteins (NCPs) in regulating the in vivo mineralization of collagen provides important insights for scientists searching for analogues of NCPs to achieve in vitro collagen mineralization. Polyampholyte carboxymethyl chitosan (CMC) has both carboxyl and amino groups, which allows it to act as a cationic or anionic polyelectrolyte below or above its isoelectric point (IP), respectively. In this study, CMC was employed as the analogue of NCPs to stabilize amorphous calcium phosphate (ACP) under acidic conditions (pH < 3.5) via the formation of CMC/ACP nanocomplexes. In the presence of both ACP nanoparticles and acid collagen molecules, ACP nanoparticles could be integrated into collagen fibrils during the process of collagen self-assembly and achieve intrafibrillar mineralization of collagen in vitro (i.e., synchronous self-assembly/mineralization (SSM) of collagen). This mode of mineralization is different from established mechanisms in which mineralization follows the self-assembly (MFS) of collagen. Thus, SSM provides a new strategy for developing materials from mineralized collagen scaffolds.展开更多
Based on special antipolyelectrolyte effect of zwitterion polymer with same quantity of anionic and cationic charges, we developed two types of salt-responsive polyampholytes, one with high molecular weight and low ch...Based on special antipolyelectrolyte effect of zwitterion polymer with same quantity of anionic and cationic charges, we developed two types of salt-responsive polyampholytes, one with high molecular weight and low charge density(HvL) and the other with low molecular weight and high charge density(LvH), by inverse emulsion polymerization. Molecular structure and salt-responsiveness of them were characterized by 1 H-NMR and rheology measurement, respectively. HvL and LvH were evaluated in saturated-salt bentonite suspension and influences of their ratio on apparent viscosity and fluid loss were investigated as well. The results indicate that HvL is better at decreasing fluid loss while LvH is better at maintaining low viscosity. A saturated saltwater drilling fluid centering on HvL and Lv H with simple formula was designed and applied. It is indicated that salt-responsive polyampholytes are fundamentally better than AM-AMPS anionic copolymer and AM-AMPS-DMDAAC amphoteric copolymer. The saturated saltwater drilling fluid has excellent thermal stability, tolerance to bentonite and shale cuttings, and certain resistance to CaCl_2. Salt-responsive polyampholytes can be used in KCl-saturated drilling fluid, with universal adaptability.展开更多
In this paper, the continuum self-consistent field theory （SCFT） is applied to study the structure and the interaction of the adsorption of symmetrical ABA polyampholytes （PAs） between two neutral planes. It is fo...In this paper, the continuum self-consistent field theory （SCFT） is applied to study the structure and the interaction of the adsorption of symmetrical ABA polyampholytes （PAs） between two neutral planes. It is found that the amounts of all the conformations decrease with the increase of the charge fraction of polymer chain, and increase with the increase of the bulk salt concentration and become saturated at high bulk salt concentration. The effective interaction between the two planes presented a long-range repulsion. Splitting it into various components and relating with the dependence of the variations of the conformations on environment parameters, we ,try to find the origin of the total long-range interaction between the two planes.展开更多
基金supported by the National Natural Science Foundation of China(No.22273114)the National Key R&D Program of China(No.2023YFE0124500)+1 种基金the National Key R&D Program of China(No.2023YFC2411203)International Partnership Program of the Chinese Academy of Sciences(No.027GJHZ2022061FN).
文摘Polyampholyte gels,which have hierarchical structures,exhibit excellent self-healing properties and have great promise for biomaterials and bioengineering.We investigated the relationship between microscopic structures and macroscopic viscoelastic properties of polyampholyte gels and found three factors influencing their viscoelastic properties,including the chemical crosslinking bonds,topological entanglements controlled by monomer concentration,and the ionic bonds.Ionic strength plays a major role on the strength of ionic bonds.A crossover point of elastic modulus and loss modulus was observed in the dynamic frequency sweeps at low monomer concentration or low chemical crosslinking density for gels with intermediate strength of ionic bonds.The solid-liquid transition signaled by the crossover point is a typical feature of dynamic associated gels,representing the dynamical association-dissociation of the ionic bonds and full relaxation of the topological entanglements in the gel network.While the crossover point disappears when the ionic bonds are too weak or too strong to form“permanent”bonds.Consistently,in the non-linear yielding measurement,gels with intermediate strength of the ionic bonds are ductile and yield at very large shear strain due to the self-healing properties and the dynamic association-dissociation of the ionic bonds.But the self-healing properties disappear when the ionic bond strength is too weak or too strong.Our work reveals the mechanism of how the dynamic association-dissociation of ionic bonds influences both the linear and non-linear viscoelastic properties of the polyampholyte gels.
基金financial support of the project from the National Natural Science Foundation of China (Nos. 31870947 and 81571016)
文摘The significant role of the polyelectrolytic nature of non-collagenous proteins (NCPs) in regulating the in vivo mineralization of collagen provides important insights for scientists searching for analogues of NCPs to achieve in vitro collagen mineralization. Polyampholyte carboxymethyl chitosan (CMC) has both carboxyl and amino groups, which allows it to act as a cationic or anionic polyelectrolyte below or above its isoelectric point (IP), respectively. In this study, CMC was employed as the analogue of NCPs to stabilize amorphous calcium phosphate (ACP) under acidic conditions (pH < 3.5) via the formation of CMC/ACP nanocomplexes. In the presence of both ACP nanoparticles and acid collagen molecules, ACP nanoparticles could be integrated into collagen fibrils during the process of collagen self-assembly and achieve intrafibrillar mineralization of collagen in vitro (i.e., synchronous self-assembly/mineralization (SSM) of collagen). This mode of mineralization is different from established mechanisms in which mineralization follows the self-assembly (MFS) of collagen. Thus, SSM provides a new strategy for developing materials from mineralized collagen scaffolds.
基金Supported by the China National Science and Technology Major Project(2017ZX05009-003,2016ZX05020-004,2016ZX05040-005)
文摘Based on special antipolyelectrolyte effect of zwitterion polymer with same quantity of anionic and cationic charges, we developed two types of salt-responsive polyampholytes, one with high molecular weight and low charge density(HvL) and the other with low molecular weight and high charge density(LvH), by inverse emulsion polymerization. Molecular structure and salt-responsiveness of them were characterized by 1 H-NMR and rheology measurement, respectively. HvL and LvH were evaluated in saturated-salt bentonite suspension and influences of their ratio on apparent viscosity and fluid loss were investigated as well. The results indicate that HvL is better at decreasing fluid loss while LvH is better at maintaining low viscosity. A saturated saltwater drilling fluid centering on HvL and Lv H with simple formula was designed and applied. It is indicated that salt-responsive polyampholytes are fundamentally better than AM-AMPS anionic copolymer and AM-AMPS-DMDAAC amphoteric copolymer. The saturated saltwater drilling fluid has excellent thermal stability, tolerance to bentonite and shale cuttings, and certain resistance to CaCl_2. Salt-responsive polyampholytes can be used in KCl-saturated drilling fluid, with universal adaptability.
基金financially supported by the National Natural Science Foundation of China(Nos.21374011 and 21434001)973 project 2011CB808502
文摘In this paper, the continuum self-consistent field theory （SCFT） is applied to study the structure and the interaction of the adsorption of symmetrical ABA polyampholytes （PAs） between two neutral planes. It is found that the amounts of all the conformations decrease with the increase of the charge fraction of polymer chain, and increase with the increase of the bulk salt concentration and become saturated at high bulk salt concentration. The effective interaction between the two planes presented a long-range repulsion. Splitting it into various components and relating with the dependence of the variations of the conformations on environment parameters, we ,try to find the origin of the total long-range interaction between the two planes.
