The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and...The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and most importantly, no paradoxical parameters appeared in the model. Moreover, it can simulate different microstructure patterns owing to the use of a new different free energy function for the simulation of morphologies of polymer. The new free energy function considers both the cases of T〈Tm and T≥Tm, which is more reasonable than that in published literatures that all ignored the T≥Tm case. In order to show the validity of the modified model, the finite difference method is used to solve the model and different crystallization morphologies during the solidification process of isotactic polystyrene are obtained under different conditions. Numerical results show that the growth rate of the initial secondary arms is obviously increased as the anisotropy strength increases. But the anisotropy strength seems to have no apparent effect on the global growth rate. The whole growth process of the dendrite depends mainly upon the latent heat and the latent heat has a direct effect on the tip radius and tip velocity of side branches.展开更多
It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPM...It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPMADOX conjugate was designed. di HPMA dendritic copolymer with GFLG segments in the branches which are sensitive to the intracellular enzyme of the tumor was prepared through RAFT polymerization. DOX was attached to dendritic di HPMA polymer through a pH-sensitive hydrazone bond. The dendritic pdi HPMA-DOX conjugate self-assembled into nanoparticles with an ideal spherical shape at a mean size of 103 nm. The DOX attached to the polymeric carrier was released in an acidic environment, and the GFLG linker for synthesizing the dendritic vehicle with a high molecular weight（M_W, 220 kDa） was cleaved to release low MWsegments（〈40 kDa） in the presence of cathepsin B. The dendritic polymeric conjugate was internalized via an endocytic pathway, and then released the anticancer drug, which led to significant cytotoxicity for tumors. The blood circulation time was profoundly prolonged, resulting in high accumulation of DOX into tumors. In vivo anti-tumor experiments with 4 T1 tumor bearing mice demonstrated that the conjugate had a better antitumor efficacy in comparison with free DOX. Additionally, body weight measurements and histological examinations indicated that the conjugate showed low toxicities to normal tissues. This dendritic polymeric drug carrier in a response to intracellular enzyme and acidic pH of tumor tissue or cells holds great promise in tumor-targeted therapy.展开更多
Through a controllable“reactivate””graft”synthetic route,two asymmetrical“Janus”dendronized polymers(DPs)were successfully synthesized.Dendrons were grafted to a linear polymer motherboard by a story-by-story co...Through a controllable“reactivate””graft”synthetic route,two asymmetrical“Janus”dendronized polymers(DPs)were successfully synthesized.Dendrons were grafted to a linear polymer motherboard by a story-by-story constructionmethod.Due to the heterogenetic“Janus”structure,with orderly arranged chromophore moieties,the polymers demonstrated extremely large second-order nonlinear optical(NLO)coefficients and excellent NLO thermal stability.DP-4l and DP-6l had high d33 values of 232 and 227 pm/V,respectively,which reached the highest value reported so far for linear-based polymers containing simple azo-chromophore moieties.The controllable synthesis sheds light on the structure–property relationships of NLO polymers and other dendronized-structure functional polymers.展开更多
Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-a...Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-anode-based Li-ion batteries[1].However,the hostless structural evolution of Li metal during the anode process easily forms dendrites and could lead to a hazardous short circuit of batteries[2].In addition.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
基金This work is supported by the National Natural Science Foundation of China （No.11402210）, the Natural Science Foundation of Shanxi Province （No.2012011019-2）, and the Doctoral Fund of Taiyuan University of Science and Technology （No.20152024）.
文摘The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and most importantly, no paradoxical parameters appeared in the model. Moreover, it can simulate different microstructure patterns owing to the use of a new different free energy function for the simulation of morphologies of polymer. The new free energy function considers both the cases of T〈Tm and T≥Tm, which is more reasonable than that in published literatures that all ignored the T≥Tm case. In order to show the validity of the modified model, the finite difference method is used to solve the model and different crystallization morphologies during the solidification process of isotactic polystyrene are obtained under different conditions. Numerical results show that the growth rate of the initial secondary arms is obviously increased as the anisotropy strength increases. But the anisotropy strength seems to have no apparent effect on the global growth rate. The whole growth process of the dendrite depends mainly upon the latent heat and the latent heat has a direct effect on the tip radius and tip velocity of side branches.
基金supported by the National Natural Science Foundation of China (51673127 and 8162103)International Science and Technology Cooperation Program of China (2015DFE52780 and 81220108013)International Science and Technology Cooperation Program of Chengdu (2016-GH03-00005-HZ)
文摘It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPMADOX conjugate was designed. di HPMA dendritic copolymer with GFLG segments in the branches which are sensitive to the intracellular enzyme of the tumor was prepared through RAFT polymerization. DOX was attached to dendritic di HPMA polymer through a pH-sensitive hydrazone bond. The dendritic pdi HPMA-DOX conjugate self-assembled into nanoparticles with an ideal spherical shape at a mean size of 103 nm. The DOX attached to the polymeric carrier was released in an acidic environment, and the GFLG linker for synthesizing the dendritic vehicle with a high molecular weight（M_W, 220 kDa） was cleaved to release low MWsegments（〈40 kDa） in the presence of cathepsin B. The dendritic polymeric conjugate was internalized via an endocytic pathway, and then released the anticancer drug, which led to significant cytotoxicity for tumors. The blood circulation time was profoundly prolonged, resulting in high accumulation of DOX into tumors. In vivo anti-tumor experiments with 4 T1 tumor bearing mice demonstrated that the conjugate had a better antitumor efficacy in comparison with free DOX. Additionally, body weight measurements and histological examinations indicated that the conjugate showed low toxicities to normal tissues. This dendritic polymeric drug carrier in a response to intracellular enzyme and acidic pH of tumor tissue or cells holds great promise in tumor-targeted therapy.
基金This research was made possible as a result of a generous grant from NSFC Foundation(Grant Number 21734007).
文摘Through a controllable“reactivate””graft”synthetic route,two asymmetrical“Janus”dendronized polymers(DPs)were successfully synthesized.Dendrons were grafted to a linear polymer motherboard by a story-by-story constructionmethod.Due to the heterogenetic“Janus”structure,with orderly arranged chromophore moieties,the polymers demonstrated extremely large second-order nonlinear optical(NLO)coefficients and excellent NLO thermal stability.DP-4l and DP-6l had high d33 values of 232 and 227 pm/V,respectively,which reached the highest value reported so far for linear-based polymers containing simple azo-chromophore moieties.The controllable synthesis sheds light on the structure–property relationships of NLO polymers and other dendronized-structure functional polymers.
基金supported by the National Natural Science Foundation of China(22279028,22179018)the Natural Science Foundation of Hebei Province(B2021205019)the 333 Project of Hebei Province(C20231106).
文摘Rechargeable lithium-metal batteries that are operated based on reversible metal plating and stripping during the charge/discharge process are known for their high energy density far beyond the conventional,graphite-anode-based Li-ion batteries[1].However,the hostless structural evolution of Li metal during the anode process easily forms dendrites and could lead to a hazardous short circuit of batteries[2].In addition.
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.
