In this study,two new dendronized nonlinear optical(NLO)polymers were synthesized with high FTC chromophore loading density by introduction of high generation chromophore dendrons on the side chains.Due to their suita...In this study,two new dendronized nonlinear optical(NLO)polymers were synthesized with high FTC chromophore loading density by introduction of high generation chromophore dendrons on the side chains.Due to their suitable molecular weights,both of them possessed good solubility in common solvents.They also inherited the advantages of dendrimers(large NLO coefficient),especially for PG2 whose NLO coefficient d33 value was as high as 282 pm·V^–1.Also,PG2 had a good temporal stability with 80%of its maximum value being retained at the temperature as high as 129℃.展开更多
The interracial assembly of photo-induced dimerization of atypical anthracene-containing amphiphilic dendron and host-vip interaction with γ-cyclodextrin has been investigated. It has been proved that even without ...The interracial assembly of photo-induced dimerization of atypical anthracene-containing amphiphilic dendron and host-vip interaction with γ-cyclodextrin has been investigated. It has been proved that even without long alkyl chain the amphiphilic dendron could still form stable Langmuir monolayer at the air/water interface. Through the host-vip interaction,γ-cyclodextrin can be used to encapsulate two headgroups of amphiphilic dendron in the antiparallel direction. However, the formed host-vip complex was sensitive to the surface pressure. Slight compression of surface pressure led amphiphilic dendron to reassemble into nanofibers through the strong π-π stacking between headgroups. On the other hand, under in situ irradiation, the amphiphilic dendron was stabilized in the cavity of γ- cyclodextrin through headgroup dimerization and the host-vip complex further irregularly aggregated to nanoparticles. Meanwhile, γ-cyclodextrin, as a silencer, blocked the supramolecular chirality transfer. Our conclusion was demonstrated through UV/vis, FT-IR, CD spectrum and AFM images, respectively.展开更多
Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interacti...Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.展开更多
The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers h...The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers has shown typical weight average molecular weight （Mw） of 41554 and a polydispersity of 2.74.展开更多
Three novel redox-active percec-type dendrons were synthesized by mucleophilic substitution reaction of 11-bromoundecyl ferrocene and substituted benzoate.All the resultant ferrocenyl-modified dendrons were confirmed ...Three novel redox-active percec-type dendrons were synthesized by mucleophilic substitution reaction of 11-bromoundecyl ferrocene and substituted benzoate.All the resultant ferrocenyl-modified dendrons were confirmed through FT-IR,NMR,and elemental analysis,etc.Furthermore,the thermal properties and electrochemical behavior of these dendrons were monitored with thermogravimetry analysis（TG）,differential scanning calorimetry（DSC）,polarized optical microscope（POM）,and cyclic voltammetry（CV）. Abound phase behavior and reversible electrochemical redox reaction process in the DMF solution of these dendrons was observed.展开更多
A series of thermoresponsive cationic dendronized copolymers and their corresponding nano gels containing den dritic oligoethylene glycol(OEG)units and guanidine groups were prepared,and their complexation,protect!on,...A series of thermoresponsive cationic dendronized copolymers and their corresponding nano gels containing den dritic oligoethylene glycol(OEG)units and guanidine groups were prepared,and their complexation,protect!on,and release of nucleic acids were investigated.The dendritic OEGs endow these copolymer materials with good biocompatibility and characteristic thermoresponsiveness,while cationic guanidine groups can efficiently bind with the nucleic acids.The dendritic topology also affords the copolymers specific shielding effect which plays an essential role in protecting the activity of nucleic acids.At room temperature,dendronized copolymers and the corresponding nanogels could efficiently capture and condense the nucleic acids,while above their cloud points(Tcps),more than 75%of siRNA could be released in 1 h triggered by ATP.More importantly,the copolymer showed protective capability to siRNA,while nano gels exhibit even better protection when compared to the copolymers due to the synergetic effect from the three-dimensional cross-linked network and high density of dendritic units in vicinity.This kind of smart dendr on ized copolymer nano gels form a no vel class of scaffolds as promisi ng materials for biomedical applicatio ns.展开更多
Helical poly(arylacetylene)s have formed an intriguing class of polymers;whose chiralities are dynamic and liable to external stimuli.By combining dendronized polymer topology with dendritic oligoethylene glycols(OEGs...Helical poly(arylacetylene)s have formed an intriguing class of polymers;whose chiralities are dynamic and liable to external stimuli.By combining dendronized polymer topology with dendritic oligoethylene glycols(OEGs);we here report on synthesis of a homologous series of thermoresponsive dendronized poly(arylacetylene)s with either poly(phenyl acetylene)or poly(naphthalene acetylene)as the backbones;and investigate tunability of their helical conformations.These polymers carry dendritic OEG pendants with either methoxyl-or ethoxyl-terminals to tune their unprecedent thermoresponsive behaviors;and at the same time;dendritic shielding plays an important role in mediating their thermal phase transition temperatures.Helicity of these polymers is originated from the chiral alanine or phenylalanine moieties within the dendritic pendants;which can be tailored through manipulating solvation in different organic solvents or via thermal dehydration and collapse in water.Furthermore;achiral additives such as linear or dendritic OEGs and benzene derivatives can act similarly as thermal dehydration to induce chirality transitions of these polymers in aqueous phase through interplay competitions between the additives and the polymers against their hydration.展开更多
Dendronized polymers(DenPols)with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials.However,it still has lacked a rapid and efficient approach to the facile synt...Dendronized polymers(DenPols)with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials.However,it still has lacked a rapid and efficient approach to the facile synthesis of DenPols with high-generation and well-defined structures.Herein,we report a“m+n”grafting-onto strategy combined with the copper-catalyzed azide-alkyne cycloaddition(CuAAC)reaction with reaction-enhanced reactivity of intermediates(RERI)mechanism for synthesizing DenPols G_(m+n) by attaching n-generation dendrons(G_(n))onto the m-generation DenPols G_(m).In this“m+n”grafting-onto strategy,the DenPols G_(m)(m=1,2)bearing 1,3-triazido branches on the repeating unit were capable of RERI effect that guaranteed the CuAAC reaction in an extremely efficient way with ultrafast kinetics to synthesize third-,fourth-and fifth-generation DenPols(G_(1+2),G_(1+3),G_(1+4),G_(2+2),and G_(2+3))with near quantitative grafting density and narrow distribution.Moreover,these resultant DenPols G_(m+n) had more terminal groups per repeating unit due to the three branches of 1,3-triazido structure,exhibiting valuable potential opportunities for molecular surface engineering.The development of this“m+n”grafting-onto strategy with RERI mechanism not only presents a new avenue for ultrafast preparing DenPols but also holds great promise for preparing unimolecular materials with more functional terminal groups.展开更多
A new kind of dendronized poly(methylsiloxane) (3a and 3b) with appendent Fréchet-type poly(aryl ether) dendrons has been synthesized and characterized by GPC, DSC, TGA, fluorescence and UV-Vis spectra.
A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are described.These ...A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are described.These polymers are constructed in each repeat unit with various generations of hydrophobic 4-aminoproline and hydrophilic oligoethylene glycol (OEG)-based dendrons,and their over-all hydrophilicity is tuned by varying these dendron generations.Polymers with or without the first generation of proline dendron show good water solubility at room temperature,but exhibit typical thermoresponsive behaviors at elevated temperatures as characterized by turbidity measurements using UV-vis spectroscopy,while the polymer with the secondary generation of proline dendron is not soluble in water.All polymers show ordered secondary structures as evidenced by the optical rotation and circular dichroism experiments.Finally,assembly of these amphiphilic homopolymers into porous films via breath figure (BF) technique is described,and polymer structures are found to show significant influence on the morphology of porous film.展开更多
Dendronized hyperbranched polymer （DHP） is a new kind of polymer, which combines the advantages of dendrimers and hy- perbranched polymers. In this work, two dendronized hyperbranched polymers, DttPG0 and DHPG1, wer...Dendronized hyperbranched polymer （DHP） is a new kind of polymer, which combines the advantages of dendrimers and hy- perbranched polymers. In this work, two dendronized hyperbranched polymers, DttPG0 and DHPG1, were successfully pre- pared through the simple ＂A3＋B2＂ type Sonogashira coupling reaction. The nonlinear optical （NLO） effects of DHPG0 and DItPG1, characterized by the d33 values, were 183 and 220 pm V-1 respectively, higher than those of their analogues of den- dronized polymers and dendrimers, thanks to the special topological structure. Also, the obtained polymers displayed excellent solubility, good processability, and high thermal stability.展开更多
Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept ...Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept of "isolation chromophore", "isolation group" and dendritic structure, a dendritic molecule D-NS and a dendronized hyperbranched polymer DHP-NS are prepared to investigate their structure-property relationship. For the small dendritic molecule D-NS, it exhibits a high d33 value of 140 pm/V.But this value can be easily dropped when the temperature is higher than 50 °C, which extremely limits its real application. After introducing D-NS into a dendronized hyperbranched polymer chains, the obtained DHP-NS also shows a high d33 value of101 pm/V, but much better stability than D-NS. Even when its thin film was heated to 120 °C, no obvious decay can be observed in the d33 value of DHP-NS. This work demonstrates an effective strategy to realize both large NLO effect and good stability simultaneously.展开更多
A new type of dendritic polymer, named dendronized hyperbranched polymer (DHP), was prepared successfully by the macro-monomer approach. Thanks to the perfect 3D isolation effects, DHPG1 exhibited good NLO property wi...A new type of dendritic polymer, named dendronized hyperbranched polymer (DHP), was prepared successfully by the macro-monomer approach. Thanks to the perfect 3D isolation effects, DHPG1 exhibited good NLO property with d 33 value of 133 pm/V, higher than its analogues of dendronized polymer and dendrimer, and its stability of NLO effect was also enhanced.展开更多
Two poly(benzyl ether) dendrons,decorated in their periphery with nitrile groups,were divergently synthesized and fully characterized.Their gelation properties were studied by using scanning electron microscopy(SEM),X...Two poly(benzyl ether) dendrons,decorated in their periphery with nitrile groups,were divergently synthesized and fully characterized.Their gelation properties were studied by using scanning electron microscopy(SEM),X-ray crystal structure analysis and concentration-and temperature-dependent 1 H NMR spectroscopy.It was found that the gelation capability of these dendrons was highly dependent on dendron generation,and the second-generation dendron G 2-CN proved to be highly efficient organogelator despite the lacking of any conventional gelation motifs,such as amides,long alkyl side chains and steroidal groups.The multiple strong-stacking interactions and hydrogen bonding interactions due to the peripheral isophthalonitrile motifs were proved to be the main driving forces to form the self-assembled gel.展开更多
Insulated molecular wires of poly(phenylenevinylene) (PPV) were prepared by wrapping the conjugated backbones with dendrons through a noncovalent approach. It was found that electrostatic interaction between the quate...Insulated molecular wires of poly(phenylenevinylene) (PPV) were prepared by wrapping the conjugated backbones with dendrons through a noncovalent approach. It was found that electrostatic interaction between the quaternary ammonium groups of PPV-1 and the carboxylate moieties in dendrons induced the packing of dendrons along PPV-1 conjugated backbones. Absorption and emission spectroscopic examinations in solution and solid film indicated that the PPV-1 backbones adopted a more planar and isolated conformation in the complexes. Furthermore, interchain interactions in the complexes could be greatly reduced, improving the quantum yield of PPV-1.展开更多
Three dendronized polymers from generation one to generation three have been prepared by complexing negatively charged Frechet-type dendrons with a polyanion, poly（diallydimethylammoniurn chloride） （PDADMAC）. The ...Three dendronized polymers from generation one to generation three have been prepared by complexing negatively charged Frechet-type dendrons with a polyanion, poly（diallydimethylammoniurn chloride） （PDADMAC）. The gaffing degree has been confirmed mainly by elemental analysis. In dilute solutions of tetrahydrofuran, static light scattering studies indicate that the first generation complex has a coil-like conformation, even more flexible than PDADMAC. The second and third generation complexes exhibit polyelectrolyte behavior. Dynamic light scattering experiments indicate that all the three complexes have almost the same hydrodynamic radius, indicating that they might own similar coil conformation. Atomic force microscopy shows the existence of disordered globules formed by one or a couple of complex coils. All these observations can be explained by the flowerlike coil conformation, which is formed by the intra-molecular association. This is totally different from the stretched chain conformation formed by covalently connected dendronized polymers. This result also explains why some ordered supramolecular structures, found in condensed state of the similar complexes, are not as perfect as those of conventional dendronized polymers.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 21734007)
文摘In this study,two new dendronized nonlinear optical(NLO)polymers were synthesized with high FTC chromophore loading density by introduction of high generation chromophore dendrons on the side chains.Due to their suitable molecular weights,both of them possessed good solubility in common solvents.They also inherited the advantages of dendrimers(large NLO coefficient),especially for PG2 whose NLO coefficient d33 value was as high as 282 pm·V^–1.Also,PG2 had a good temporal stability with 80%of its maximum value being retained at the temperature as high as 129℃.
基金supported by the National Natural Science Foundation of China(Nos.21021003 and 50673095)the Basic Research Development Program(Nos.2007CB808005 and 2009CB930802)the Fund of the Chinese Academy of Sciences
文摘The interracial assembly of photo-induced dimerization of atypical anthracene-containing amphiphilic dendron and host-vip interaction with γ-cyclodextrin has been investigated. It has been proved that even without long alkyl chain the amphiphilic dendron could still form stable Langmuir monolayer at the air/water interface. Through the host-vip interaction,γ-cyclodextrin can be used to encapsulate two headgroups of amphiphilic dendron in the antiparallel direction. However, the formed host-vip complex was sensitive to the surface pressure. Slight compression of surface pressure led amphiphilic dendron to reassemble into nanofibers through the strong π-π stacking between headgroups. On the other hand, under in situ irradiation, the amphiphilic dendron was stabilized in the cavity of γ- cyclodextrin through headgroup dimerization and the host-vip complex further irregularly aggregated to nanoparticles. Meanwhile, γ-cyclodextrin, as a silencer, blocked the supramolecular chirality transfer. Our conclusion was demonstrated through UV/vis, FT-IR, CD spectrum and AFM images, respectively.
基金the National Natural Science Foundation of China(Nos.21374058,21474060 and 21574078)the Ph.D. Programs Foundation of Ministry of Education of China(No 201331081100166)the Shanghai Rising-Star Program(No.16QA1401800)
文摘Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.
文摘The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers has shown typical weight average molecular weight （Mw） of 41554 and a polydispersity of 2.74.
基金The financial support from the NSFC(No.50873037)China Postdoctoral Science Foundation(No.20100470908, 201104349)the NSF of Guangdong Province(No.10451064101005118) is gratefully acknowledged
文摘Three novel redox-active percec-type dendrons were synthesized by mucleophilic substitution reaction of 11-bromoundecyl ferrocene and substituted benzoate.All the resultant ferrocenyl-modified dendrons were confirmed through FT-IR,NMR,and elemental analysis,etc.Furthermore,the thermal properties and electrochemical behavior of these dendrons were monitored with thermogravimetry analysis（TG）,differential scanning calorimetry（DSC）,polarized optical microscope（POM）,and cyclic voltammetry（CV）. Abound phase behavior and reversible electrochemical redox reaction process in the DMF solution of these dendrons was observed.
基金the National Natural Science Foundation of China(Nos.21971161,21971160,and 21574078)Shanghai Pujiang Program(No.19PJ1403700)Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning.
文摘A series of thermoresponsive cationic dendronized copolymers and their corresponding nano gels containing den dritic oligoethylene glycol(OEG)units and guanidine groups were prepared,and their complexation,protect!on,and release of nucleic acids were investigated.The dendritic OEGs endow these copolymer materials with good biocompatibility and characteristic thermoresponsiveness,while cationic guanidine groups can efficiently bind with the nucleic acids.The dendritic topology also affords the copolymers specific shielding effect which plays an essential role in protecting the activity of nucleic acids.At room temperature,dendronized copolymers and the corresponding nanogels could efficiently capture and condense the nucleic acids,while above their cloud points(Tcps),more than 75%of siRNA could be released in 1 h triggered by ATP.More importantly,the copolymer showed protective capability to siRNA,while nano gels exhibit even better protection when compared to the copolymers due to the synergetic effect from the three-dimensional cross-linked network and high density of dendritic units in vicinity.This kind of smart dendr on ized copolymer nano gels form a no vel class of scaffolds as promisi ng materials for biomedical applicatio ns.
基金supported by the National Natural Science Foundation of China(22271183,22371179,21971160).
文摘Helical poly(arylacetylene)s have formed an intriguing class of polymers;whose chiralities are dynamic and liable to external stimuli.By combining dendronized polymer topology with dendritic oligoethylene glycols(OEGs);we here report on synthesis of a homologous series of thermoresponsive dendronized poly(arylacetylene)s with either poly(phenyl acetylene)or poly(naphthalene acetylene)as the backbones;and investigate tunability of their helical conformations.These polymers carry dendritic OEG pendants with either methoxyl-or ethoxyl-terminals to tune their unprecedent thermoresponsive behaviors;and at the same time;dendritic shielding plays an important role in mediating their thermal phase transition temperatures.Helicity of these polymers is originated from the chiral alanine or phenylalanine moieties within the dendritic pendants;which can be tailored through manipulating solvation in different organic solvents or via thermal dehydration and collapse in water.Furthermore;achiral additives such as linear or dendritic OEGs and benzene derivatives can act similarly as thermal dehydration to induce chirality transitions of these polymers in aqueous phase through interplay competitions between the additives and the polymers against their hydration.
基金the National Natural Science Foundation of China(Nos.22071271,22371313)Natural Science Foundation of Guangdong Province(2024A1515011133 and 2021A1515110853)the Fundamental Research Funds for the Central Universities(23yxqntd002).
文摘Dendronized polymers(DenPols)with tunable shape and surface property have been recognized as a type of promising unimolecular nanomaterials.However,it still has lacked a rapid and efficient approach to the facile synthesis of DenPols with high-generation and well-defined structures.Herein,we report a“m+n”grafting-onto strategy combined with the copper-catalyzed azide-alkyne cycloaddition(CuAAC)reaction with reaction-enhanced reactivity of intermediates(RERI)mechanism for synthesizing DenPols G_(m+n) by attaching n-generation dendrons(G_(n))onto the m-generation DenPols G_(m).In this“m+n”grafting-onto strategy,the DenPols G_(m)(m=1,2)bearing 1,3-triazido branches on the repeating unit were capable of RERI effect that guaranteed the CuAAC reaction in an extremely efficient way with ultrafast kinetics to synthesize third-,fourth-and fifth-generation DenPols(G_(1+2),G_(1+3),G_(1+4),G_(2+2),and G_(2+3))with near quantitative grafting density and narrow distribution.Moreover,these resultant DenPols G_(m+n) had more terminal groups per repeating unit due to the three branches of 1,3-triazido structure,exhibiting valuable potential opportunities for molecular surface engineering.The development of this“m+n”grafting-onto strategy with RERI mechanism not only presents a new avenue for ultrafast preparing DenPols but also holds great promise for preparing unimolecular materials with more functional terminal groups.
文摘A new kind of dendronized poly(methylsiloxane) (3a and 3b) with appendent Fréchet-type poly(aryl ether) dendrons has been synthesized and characterized by GPC, DSC, TGA, fluorescence and UV-Vis spectra.
基金supported by ETH Research Grant ETH-1608-1the Swiss National Science Foundation(200021-113690)the National Natural Science Foundation of China(20374047 & 20574062)
文摘A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are described.These polymers are constructed in each repeat unit with various generations of hydrophobic 4-aminoproline and hydrophilic oligoethylene glycol (OEG)-based dendrons,and their over-all hydrophilicity is tuned by varying these dendron generations.Polymers with or without the first generation of proline dendron show good water solubility at room temperature,but exhibit typical thermoresponsive behaviors at elevated temperatures as characterized by turbidity measurements using UV-vis spectroscopy,while the polymer with the secondary generation of proline dendron is not soluble in water.All polymers show ordered secondary structures as evidenced by the optical rotation and circular dichroism experiments.Finally,assembly of these amphiphilic homopolymers into porous films via breath figure (BF) technique is described,and polymer structures are found to show significant influence on the morphology of porous film.
基金supported by the National Natural Science Foundation of China(21325416)
文摘Dendronized hyperbranched polymer （DHP） is a new kind of polymer, which combines the advantages of dendrimers and hy- perbranched polymers. In this work, two dendronized hyperbranched polymers, DttPG0 and DHPG1, were successfully pre- pared through the simple ＂A3＋B2＂ type Sonogashira coupling reaction. The nonlinear optical （NLO） effects of DHPG0 and DItPG1, characterized by the d33 values, were 183 and 220 pm V-1 respectively, higher than those of their analogues of den- dronized polymers and dendrimers, thanks to the special topological structure. Also, the obtained polymers displayed excellent solubility, good processability, and high thermal stability.
基金supported by the Startup Research Fund of Zhengzhou University(1411320006)the National Natural Science Foundation of China(21325416,21274133)
文摘Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept of "isolation chromophore", "isolation group" and dendritic structure, a dendritic molecule D-NS and a dendronized hyperbranched polymer DHP-NS are prepared to investigate their structure-property relationship. For the small dendritic molecule D-NS, it exhibits a high d33 value of 140 pm/V.But this value can be easily dropped when the temperature is higher than 50 °C, which extremely limits its real application. After introducing D-NS into a dendronized hyperbranched polymer chains, the obtained DHP-NS also shows a high d33 value of101 pm/V, but much better stability than D-NS. Even when its thin film was heated to 120 °C, no obvious decay can be observed in the d33 value of DHP-NS. This work demonstrates an effective strategy to realize both large NLO effect and good stability simultaneously.
基金supported by the National Natural Science Foundation of China(21034006)
文摘A new type of dendritic polymer, named dendronized hyperbranched polymer (DHP), was prepared successfully by the macro-monomer approach. Thanks to the perfect 3D isolation effects, DHPG1 exhibited good NLO property with d 33 value of 133 pm/V, higher than its analogues of dendronized polymer and dendrimer, and its stability of NLO effect was also enhanced.
基金supported by the National Natural Science Foundation of China (21074140 and 91027046)Institute of Chemistry,Chinese Academy of Sciences
文摘Two poly(benzyl ether) dendrons,decorated in their periphery with nitrile groups,were divergently synthesized and fully characterized.Their gelation properties were studied by using scanning electron microscopy(SEM),X-ray crystal structure analysis and concentration-and temperature-dependent 1 H NMR spectroscopy.It was found that the gelation capability of these dendrons was highly dependent on dendron generation,and the second-generation dendron G 2-CN proved to be highly efficient organogelator despite the lacking of any conventional gelation motifs,such as amides,long alkyl side chains and steroidal groups.The multiple strong-stacking interactions and hydrogen bonding interactions due to the peripheral isophthalonitrile motifs were proved to be the main driving forces to form the self-assembled gel.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20604013, 20774056, and 50533030)
文摘Insulated molecular wires of poly(phenylenevinylene) (PPV) were prepared by wrapping the conjugated backbones with dendrons through a noncovalent approach. It was found that electrostatic interaction between the quaternary ammonium groups of PPV-1 and the carboxylate moieties in dendrons induced the packing of dendrons along PPV-1 conjugated backbones. Absorption and emission spectroscopic examinations in solution and solid film indicated that the PPV-1 backbones adopted a more planar and isolated conformation in the complexes. Furthermore, interchain interactions in the complexes could be greatly reduced, improving the quantum yield of PPV-1.
基金supported by the National Natural Science Foundation of China(No.20734001)
文摘Three dendronized polymers from generation one to generation three have been prepared by complexing negatively charged Frechet-type dendrons with a polyanion, poly（diallydimethylammoniurn chloride） （PDADMAC）. The gaffing degree has been confirmed mainly by elemental analysis. In dilute solutions of tetrahydrofuran, static light scattering studies indicate that the first generation complex has a coil-like conformation, even more flexible than PDADMAC. The second and third generation complexes exhibit polyelectrolyte behavior. Dynamic light scattering experiments indicate that all the three complexes have almost the same hydrodynamic radius, indicating that they might own similar coil conformation. Atomic force microscopy shows the existence of disordered globules formed by one or a couple of complex coils. All these observations can be explained by the flowerlike coil conformation, which is formed by the intra-molecular association. This is totally different from the stretched chain conformation formed by covalently connected dendronized polymers. This result also explains why some ordered supramolecular structures, found in condensed state of the similar complexes, are not as perfect as those of conventional dendronized polymers.
