Promoting community governance and service innovation is the theme of the times for comprehensively deepening reforms in the field of community construction.The stability and development of the most basic rural commun...Promoting community governance and service innovation is the theme of the times for comprehensively deepening reforms in the field of community construction.The stability and development of the most basic rural community is another important task of community governance.The current rural social governance work is extremely weak,seriously affecting the process of the entire social governance work.Constructing the path of rural community governance has become an important task for the majority of theoretical workers and grassroots practitioners.Taking Chaoyang Community,Tongchuan District,Dazhou,Sichuan Province as an example,with the goal of creating a community with the rule of law,peace,harmony,beauty and livability,a new model and new path to build community governance is proposed in this article.展开更多
With adjustment of rural industrial structure,development of rural secondary and tertiary industries,and transfer of rural labor,rural land circulation is accelerating. However,due to ideas,household contract responsi...With adjustment of rural industrial structure,development of rural secondary and tertiary industries,and transfer of rural labor,rural land circulation is accelerating. However,due to ideas,household contract responsibility system,and lack of well-established market mechanism and effective management organizations,land circulation in Dazhou is still very slow and its contribution to increase of farmers' income is to be improved. Through survey on increase of farmers' income after land circulation in Dazhou,it analyzed plight of land circulation,in the hope of seeking feasible paths for increasing farmers' income.展开更多
Integration of three industries is an important way to achieve structural reform of the supply side of agriculture. The key to the development of agricultural three-industry integration is the supply of land. Starting...Integration of three industries is an important way to achieve structural reform of the supply side of agriculture. The key to the development of agricultural three-industry integration is the supply of land. Starting from this point,the land consolidation,increase and decrease linkage,industrial and mining wasteland reclamation and rural stock construction land that provide land use security for three-industry integration,as well as industrial policies,guarantee mechanism and other special provisions for the development of three-industry integration are reviewed in this paper.展开更多
It remains challenging to synthesize supertough thermoplastic elastomers(TPEs)since the stretchability and tensile strength are mutually exclusive.Here,we report a one-pot strategy for the preparation of sustainable,t...It remains challenging to synthesize supertough thermoplastic elastomers(TPEs)since the stretchability and tensile strength are mutually exclusive.Here,we report a one-pot strategy for the preparation of sustainable,triblock polyester TPEs consisting of poly(L-lactide)(PLLA)hard segments and poly(ɛ-caprolactone)-co-poly(δ-valerolactone)(PCVL)soft segments.The TPEs were synthesized successfully with high stretchability(up to 2100%)and strong tensile strength(up to 71.5 MPa)without requiring specific functionalized groups by simply adjusting the polymer microstructures,which,in turn,exhibited a world’s record toughness of 445 MJ/m^(3).Systematic investigation revealed that the block-like,gradient microstructure of PCVL improved the ductility by providing a flexible elastic network and enhancing the tensile strength through strain-induced crystallization.The practicability of this strategy was well demonstrated by lifting a water tank over 30,000 times heavier than itself and easy scale-up experiments.展开更多
It is very important to develop efficient synthetic strategies for site-specific functionalization of tetrahydroquinolines due to their indispensable roles in pharmaceutical and agrochemical industries.We apply hard/s...It is very important to develop efficient synthetic strategies for site-specific functionalization of tetrahydroquinolines due to their indispensable roles in pharmaceutical and agrochemical industries.We apply hard/soft acid/base(HSAB)theory to selective reduction of quinoline and achieve a series of C3-functionalized tetrahydroquinoline in high to excellent yields(up to 99%)under mild conditions with the catalysis of B(C_(6)F_(5))_(3).A series of in situ NMR reactions are also performed to investigate this cascade reaction.Moreover,AB type monomer 6-(dimethylsilyl)quinoline and AA/BB type monomer 6,6'-biquinoline are synthesized for polymer synthesis,which represents the first example of silicon bridged polytetrahydroquinoline.展开更多
Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other po...Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other polymerization techniques.The combination of Lewis acid(LA)and Lewis base(LB)to construct Lewis pairs(LPs)with appropriate Lewis basicity,Lewis acidity,and steric effects would significantly impact the polymerization process,including chain initiation,propagation,termination and chain transfer reaction,as well as polymerization manner of monomers.In this feature article,we briefly review recent progress made by our research group towards the living/controlled polymerization of(meth)acrylate monomers,which were accomplished by a series of newly designed LPs,including monofunctional LPs,dual-initiating LPs and intramolecular tethered trifunctional LP.This article is divided into three parts:(1)the development of monofunctional living/controlled LP polymerization system;(2)the design and preparation of dual-initiating LPs in synthesizing thermoplastic elastomers;(3)the application of intramolecular trifunctional LP to the synthesis of cyclic polymers.These developed LPPs have demonstrated their powerful capability in precise control over the molecular weight,molecular weight distribution,and monomer sequence as well as the topology of polymers.This review will serve as a good resource or guideline for researchers currently working in the area of LPP and for those who are interested in synthesizing new materials by LPP.展开更多
The poly(vinylpyridine)(PVP) based(co)polymers are of particular interest in materials science, due to their multifunctionality and diverse applications. So far, there is no report on the sequence-regulated copolymeri...The poly(vinylpyridine)(PVP) based(co)polymers are of particular interest in materials science, due to their multifunctionality and diverse applications. So far, there is no report on the sequence-regulated copolymerization of vinylpyridines(VPs) and methacrylate monomer in one-step manner yet. Here we designed and synthesized a series of guanidine phosphines as Lewis base(LB), which is combined with bulky organoaluminium to construct Lewis pairs(LPs) for polymerization of VPs. The living/controlled polymerization of 4-vinylpyridine(4-VP) or 2-vinylpyridine(2-VP) can be accomplished with remarkable efficiency by such Lewis pair polymerization(LPP), furnishing polymers with high molecular weight(up to 288 kg/mol) and narrow molecular weight distribution(as low as 1.17). Mechanistic studies reveal the interaction of LPs and formation of zwitterionic intermediates, providing solid evidences to support the proposed polymerization mechanism. More importantly, by simply adjusting the LA dosage, this LPP strategy realizes the unprecedented control over the sequence regulation of 2-VP-based copolymers from gradient to block in one-step manner, regardless of the monomer ratio, which greatly expands the versatility of the LPP.展开更多
It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and selectivity.We have developed a redox-neutral photocatalytic st...It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and selectivity.We have developed a redox-neutral photocatalytic strategy to accomplish this goal in both b-O-4 and b-1 lignin models at room temperature(RT)via proton-coupled electron transfer(PCET)process without any pretreatments of substrate,by adjusting the alkalinity of base to obtain a lignin models/base PCET pair with a bond dissociation free energy close to 102 kcal/mol.Without breaking down C_b–Ccbond and any C–O bonds,this PCET method is 100%atom economy and produces exclusive Ca–C_bbond cleavage products,such as benzaldehydes(up to 97%)and phenyl ethers(up to 96%),in high to excellent yields and selectivities.Preliminary studies indicated that the PCET strategy is also effective for the depolymerization of native lignin at RT,thus providing significantly important foundation to the depolymerization of lignin.展开更多
The globally increasing demands for polymer materials stimulate the significantly intense attention focused on the Lewis pair polymerization(LPP) of various polar vinyl monomers catalyzed by Lewis pairs(LPs) composed ...The globally increasing demands for polymer materials stimulate the significantly intense attention focused on the Lewis pair polymerization(LPP) of various polar vinyl monomers catalyzed by Lewis pairs(LPs) composed of Lewis acid(LA) and Lewis base(LB). According to the degree of interaction between LA and LB, LPs could be divided into classical Lewis adduct(CLA), interacting Lewis pair(ILP) and frustrated Lewis pair(FLP). Regulation of the Lewis basicity, Lewis acidity, and steric effects of these LPs has a significant impact on the polymer chain initiation, propagation and termination as well as chain transfer reaction during polymerization. Compared with other polymerization strategies, LPP has shown several unique advantages towards the polymerization of polar vinyl monomers such as high activity, control or livingness, mild conditions, and complete chemo-or regioselectivity. We will comprehensively review the recent advances achieved in the LPP of polar vinyl monomers according to the classification of the employed LPs based on different LAs, by highlighting the key polymerization results, polymerization mechanisms as well as the currently unmet challenges and the future research directions of LPP chemistry.展开更多
It remains challenging to achievevaluableplatformchemicals from lignin because of itscomplicated polymeric structure and inherent inert chemical activities.So far,only a fewexamples have been reported for the selectiv...It remains challenging to achievevaluableplatformchemicals from lignin because of itscomplicated polymeric structure and inherent inert chemical activities.So far,only a fewexamples have been reported for the selective cleavage of C–C bonds in lignin due to their intrinsic inertness and ubiquity.Here,we present a simple and commercially available cerium(Ⅲ)chloride(CeCl_(3))-promoted photocatalytic depolymerization strategy to realize the simultaneous cleavage and amination ofC_(α)–C_(β)bond in a variety of lignin model compounds at room temperature.This procedure does not require any pretreatments and breakdown of C–O bonds or loss ofγ-CH_(2)OHgroup to generate aldehydes(up to 97%)and N-containing products(up to 95%)in good to excellent yields.Additionally,this CeCl_(3)-based photocatalyst system could maintain excellent catalytic performance even after 10 sequential cycles with newstarting materials.Moreover,this approach realizes the precise control over the reaction via switching the external light stimuli on/off.Further,this method is effective for the depolymerization of real lignin,thus affording the corresponding cleavage and amination products of C_(α)–C_(β)bonds.展开更多
基金Supported by Project of Education Department of Sichuan Province(SQZL2017B02)Project of Sichuan University of Arts and Science(SCWL2018-122).
文摘Promoting community governance and service innovation is the theme of the times for comprehensively deepening reforms in the field of community construction.The stability and development of the most basic rural community is another important task of community governance.The current rural social governance work is extremely weak,seriously affecting the process of the entire social governance work.Constructing the path of rural community governance has become an important task for the majority of theoretical workers and grassroots practitioners.Taking Chaoyang Community,Tongchuan District,Dazhou,Sichuan Province as an example,with the goal of creating a community with the rule of law,peace,harmony,beauty and livability,a new model and new path to build community governance is proposed in this article.
基金Supported by Twelfth Five Year Plan of Dazhou Philosophy and Social Science 2011 Project(DZ14D06)
文摘With adjustment of rural industrial structure,development of rural secondary and tertiary industries,and transfer of rural labor,rural land circulation is accelerating. However,due to ideas,household contract responsibility system,and lack of well-established market mechanism and effective management organizations,land circulation in Dazhou is still very slow and its contribution to increase of farmers' income is to be improved. Through survey on increase of farmers' income after land circulation in Dazhou,it analyzed plight of land circulation,in the hope of seeking feasible paths for increasing farmers' income.
基金Project of Education Department of Sichuan Province"Study on the Distribution of Farmers'Land Value-added Income in the Process of Urbanization in Northeast Sichuan"(16SB0222)
文摘Integration of three industries is an important way to achieve structural reform of the supply side of agriculture. The key to the development of agricultural three-industry integration is the supply of land. Starting from this point,the land consolidation,increase and decrease linkage,industrial and mining wasteland reclamation and rural stock construction land that provide land use security for three-industry integration,as well as industrial policies,guarantee mechanism and other special provisions for the development of three-industry integration are reviewed in this paper.
基金supported by the National Natural Science Foundation of China(grant no.22071077)Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences(grant no.2019-16)to Y.Z.,(grant no.51525305)to Y.M.,and(grant no.51988102)to X.C.
文摘It remains challenging to synthesize supertough thermoplastic elastomers(TPEs)since the stretchability and tensile strength are mutually exclusive.Here,we report a one-pot strategy for the preparation of sustainable,triblock polyester TPEs consisting of poly(L-lactide)(PLLA)hard segments and poly(ɛ-caprolactone)-co-poly(δ-valerolactone)(PCVL)soft segments.The TPEs were synthesized successfully with high stretchability(up to 2100%)and strong tensile strength(up to 71.5 MPa)without requiring specific functionalized groups by simply adjusting the polymer microstructures,which,in turn,exhibited a world’s record toughness of 445 MJ/m^(3).Systematic investigation revealed that the block-like,gradient microstructure of PCVL improved the ductility by providing a flexible elastic network and enhancing the tensile strength through strain-induced crystallization.The practicability of this strategy was well demonstrated by lifting a water tank over 30,000 times heavier than itself and easy scale-up experiments.
基金supported by the National Natural Science Foundation of China(Grant Nos.21871107,22225104,21975102,22071077).
文摘It is very important to develop efficient synthetic strategies for site-specific functionalization of tetrahydroquinolines due to their indispensable roles in pharmaceutical and agrochemical industries.We apply hard/soft acid/base(HSAB)theory to selective reduction of quinoline and achieve a series of C3-functionalized tetrahydroquinoline in high to excellent yields(up to 99%)under mild conditions with the catalysis of B(C_(6)F_(5))_(3).A series of in situ NMR reactions are also performed to investigate this cascade reaction.Moreover,AB type monomer 6-(dimethylsilyl)quinoline and AA/BB type monomer 6,6'-biquinoline are synthesized for polymer synthesis,which represents the first example of silicon bridged polytetrahydroquinoline.
基金supported by the National Natural Science Foundation of China(22225104,22071077,21871107,21975102)China Postdoctoral Science Foundation(2022TQ0115,2022M711297)。
文摘Lewis pair polymerization(LPP)has demonstrated its unique advantages,such as high activity,high stability,and adjustable variability,towards the polymerization of(meth)acrylate monomers in comparison with the other polymerization techniques.The combination of Lewis acid(LA)and Lewis base(LB)to construct Lewis pairs(LPs)with appropriate Lewis basicity,Lewis acidity,and steric effects would significantly impact the polymerization process,including chain initiation,propagation,termination and chain transfer reaction,as well as polymerization manner of monomers.In this feature article,we briefly review recent progress made by our research group towards the living/controlled polymerization of(meth)acrylate monomers,which were accomplished by a series of newly designed LPs,including monofunctional LPs,dual-initiating LPs and intramolecular tethered trifunctional LP.This article is divided into three parts:(1)the development of monofunctional living/controlled LP polymerization system;(2)the design and preparation of dual-initiating LPs in synthesizing thermoplastic elastomers;(3)the application of intramolecular trifunctional LP to the synthesis of cyclic polymers.These developed LPPs have demonstrated their powerful capability in precise control over the molecular weight,molecular weight distribution,and monomer sequence as well as the topology of polymers.This review will serve as a good resource or guideline for researchers currently working in the area of LPP and for those who are interested in synthesizing new materials by LPP.
基金supported by the National Natural Science Foundation of China (22225104, 92356302 and 22071077)China Postdoctoral Science Foundation (2022TQ0115 and 2022M711297)。
文摘The poly(vinylpyridine)(PVP) based(co)polymers are of particular interest in materials science, due to their multifunctionality and diverse applications. So far, there is no report on the sequence-regulated copolymerization of vinylpyridines(VPs) and methacrylate monomer in one-step manner yet. Here we designed and synthesized a series of guanidine phosphines as Lewis base(LB), which is combined with bulky organoaluminium to construct Lewis pairs(LPs) for polymerization of VPs. The living/controlled polymerization of 4-vinylpyridine(4-VP) or 2-vinylpyridine(2-VP) can be accomplished with remarkable efficiency by such Lewis pair polymerization(LPP), furnishing polymers with high molecular weight(up to 288 kg/mol) and narrow molecular weight distribution(as low as 1.17). Mechanistic studies reveal the interaction of LPs and formation of zwitterionic intermediates, providing solid evidences to support the proposed polymerization mechanism. More importantly, by simply adjusting the LA dosage, this LPP strategy realizes the unprecedented control over the sequence regulation of 2-VP-based copolymers from gradient to block in one-step manner, regardless of the monomer ratio, which greatly expands the versatility of the LPP.
基金supported by the National Natural Science Foundation of China (21975102, 21871107, 21774042, and 21422401)
文摘It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and selectivity.We have developed a redox-neutral photocatalytic strategy to accomplish this goal in both b-O-4 and b-1 lignin models at room temperature(RT)via proton-coupled electron transfer(PCET)process without any pretreatments of substrate,by adjusting the alkalinity of base to obtain a lignin models/base PCET pair with a bond dissociation free energy close to 102 kcal/mol.Without breaking down C_b–Ccbond and any C–O bonds,this PCET method is 100%atom economy and produces exclusive Ca–C_bbond cleavage products,such as benzaldehydes(up to 97%)and phenyl ethers(up to 96%),in high to excellent yields and selectivities.Preliminary studies indicated that the PCET strategy is also effective for the depolymerization of native lignin at RT,thus providing significantly important foundation to the depolymerization of lignin.
基金supported by the National Natural Science Foundation of China (21774042,21871107,and 21422401)
文摘The globally increasing demands for polymer materials stimulate the significantly intense attention focused on the Lewis pair polymerization(LPP) of various polar vinyl monomers catalyzed by Lewis pairs(LPs) composed of Lewis acid(LA) and Lewis base(LB). According to the degree of interaction between LA and LB, LPs could be divided into classical Lewis adduct(CLA), interacting Lewis pair(ILP) and frustrated Lewis pair(FLP). Regulation of the Lewis basicity, Lewis acidity, and steric effects of these LPs has a significant impact on the polymer chain initiation, propagation and termination as well as chain transfer reaction during polymerization. Compared with other polymerization strategies, LPP has shown several unique advantages towards the polymerization of polar vinyl monomers such as high activity, control or livingness, mild conditions, and complete chemo-or regioselectivity. We will comprehensively review the recent advances achieved in the LPP of polar vinyl monomers according to the classification of the employed LPs based on different LAs, by highlighting the key polymerization results, polymerization mechanisms as well as the currently unmet challenges and the future research directions of LPP chemistry.
基金supported by the National Natural Science Foundation of China(grant nos.21975102,21871107,and 21774042).
文摘It remains challenging to achievevaluableplatformchemicals from lignin because of itscomplicated polymeric structure and inherent inert chemical activities.So far,only a fewexamples have been reported for the selective cleavage of C–C bonds in lignin due to their intrinsic inertness and ubiquity.Here,we present a simple and commercially available cerium(Ⅲ)chloride(CeCl_(3))-promoted photocatalytic depolymerization strategy to realize the simultaneous cleavage and amination ofC_(α)–C_(β)bond in a variety of lignin model compounds at room temperature.This procedure does not require any pretreatments and breakdown of C–O bonds or loss ofγ-CH_(2)OHgroup to generate aldehydes(up to 97%)and N-containing products(up to 95%)in good to excellent yields.Additionally,this CeCl_(3)-based photocatalyst system could maintain excellent catalytic performance even after 10 sequential cycles with newstarting materials.Moreover,this approach realizes the precise control over the reaction via switching the external light stimuli on/off.Further,this method is effective for the depolymerization of real lignin,thus affording the corresponding cleavage and amination products of C_(α)–C_(β)bonds.
