It remains a significant challenge to fabricate self-healing aerogels with excellent flame retardancy.Herein,we develop a class of biomass aerogels by electrostatically assembling chitosan(CS),phytic acid(PA),and itac...It remains a significant challenge to fabricate self-healing aerogels with excellent flame retardancy.Herein,we develop a class of biomass aerogels by electrostatically assembling chitosan(CS),phytic acid(PA),and itaconic acid(IA).The electrostatic interaction between CS and IA is weak and dynamic,so freeze-drying the solution of CS and IA enables the formation of continuous aerogel skeleton with self-healing ability and re-programmability;in comparison,the electrostatic interaction between CS and PA is strong and less dynamic,and thus mixing PA with CS in aqueous solution leads to fine precipitates of high flame retardancy due to the synergistic phosphorus-nitrogen effect.Integrating the continuous skeleton and the fine precipitates results in self-healing aerogles with UL-4 V-0 rating of flame retardancy aerogels and autoextinguishable feature.Interestingly,the aerogels after burning in flame for 30 s form a skin-core structure,and the carbonized skin protects the integrity of the aerogels and the self-healing ability of the internal parts.Therefore,this work provides a facile strategy to develop multifunctional aerogels which hold great promise for advanced applications.展开更多
Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure...Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure remains an academic challenge.Herein,by employing graphene oxide(GO)as the aerogel skeleton and utilizing poly(vinyl alcohol)(PVA)to regulate the ice crystal growth,we elucidate the relationships between the physicochemical properties of GO/PVA aerogel precursors and the nucleation and growth of ice crystals by using an ice-templating method.We demonstrate that due to the hydrogen bond formed between PVA and water molecules,resulting in the initial crystallization temperature being reduced from-12.60℃(GO/PVA-0.01)to-16.21℃(GO/PVA-0.1).Meanwhile,the strong hydrogen bond between PVA and GO limits the diffusion of water molecules,thereby inhibiting the growth of ice crystals,decreasing the pore size of the GO/PVA aerogel from 9.96 nm(GO/PVA-0.01)to 7.19 nm(GO/PVA-0.3),and thus the compressive strength of the aerogel increases from 0.045 MPa to 0.13MPa.Overall,the finding of this study can be extended to other aerogel precursors,and exhibit important scientific value and practical significance for the preparation of aerogel materials with highly controllable structures and performances.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51873133 and 51873110)the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(No.sklpme2018-4-33 and sklpme2019-4-32)Chengdu Science and Technology Bureau(No.2019-YF05-01319-SN).
文摘It remains a significant challenge to fabricate self-healing aerogels with excellent flame retardancy.Herein,we develop a class of biomass aerogels by electrostatically assembling chitosan(CS),phytic acid(PA),and itaconic acid(IA).The electrostatic interaction between CS and IA is weak and dynamic,so freeze-drying the solution of CS and IA enables the formation of continuous aerogel skeleton with self-healing ability and re-programmability;in comparison,the electrostatic interaction between CS and PA is strong and less dynamic,and thus mixing PA with CS in aqueous solution leads to fine precipitates of high flame retardancy due to the synergistic phosphorus-nitrogen effect.Integrating the continuous skeleton and the fine precipitates results in self-healing aerogles with UL-4 V-0 rating of flame retardancy aerogels and autoextinguishable feature.Interestingly,the aerogels after burning in flame for 30 s form a skin-core structure,and the carbonized skin protects the integrity of the aerogels and the self-healing ability of the internal parts.Therefore,this work provides a facile strategy to develop multifunctional aerogels which hold great promise for advanced applications.
基金financially supported by the National Natural Science Foundation of China(No.51873133)。
文摘Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure remains an academic challenge.Herein,by employing graphene oxide(GO)as the aerogel skeleton and utilizing poly(vinyl alcohol)(PVA)to regulate the ice crystal growth,we elucidate the relationships between the physicochemical properties of GO/PVA aerogel precursors and the nucleation and growth of ice crystals by using an ice-templating method.We demonstrate that due to the hydrogen bond formed between PVA and water molecules,resulting in the initial crystallization temperature being reduced from-12.60℃(GO/PVA-0.01)to-16.21℃(GO/PVA-0.1).Meanwhile,the strong hydrogen bond between PVA and GO limits the diffusion of water molecules,thereby inhibiting the growth of ice crystals,decreasing the pore size of the GO/PVA aerogel from 9.96 nm(GO/PVA-0.01)to 7.19 nm(GO/PVA-0.3),and thus the compressive strength of the aerogel increases from 0.045 MPa to 0.13MPa.Overall,the finding of this study can be extended to other aerogel precursors,and exhibit important scientific value and practical significance for the preparation of aerogel materials with highly controllable structures and performances.
