MXenes have promises in myriad applications by virtue of two-dimensional nature and adjustable functional groups.To achieve the applications,MXenes are always first prepared in the form of aqueous suspension.However,f...MXenes have promises in myriad applications by virtue of two-dimensional nature and adjustable functional groups.To achieve the applications,MXenes are always first prepared in the form of aqueous suspension.However,fast degradation caused by the attack of dissolved oxygen and water molecules is the main obstacle to the application of MXenes.It has come to light that the degradation preferentially takes place at defective sites and edges where defects enrich.To tackle this problem and increase the stability,herein,using Ti_(3)C_(2)T_(x)MXene as a model material,we report a simple yet efficient strategy for long term storage of MXene suspension by introducing glycerol,a typical polyhydric alcohol.The effectiveness of the strategy is evidenced by structural compositional and morphological investigations.Glycerol protects the defective sites of MXene flakes through restricting water and/or oxygen molecules from reactive sites.This is supported by ab initio molecular dynamics simulations that form hydrogen bonds between MXene and glycerol molecules just over defective sites.Following this mechanism,other polyhydric alcohols,such as ethylene glycol and propylene glycol,are also effective in stabilizing Ti_(3)C_(2)T_(x)MXene suspension.The strategy based on polyhydric alcohols has the potential to be extended to other MXenes,solving the most urgent challenge in the field of MXene engineering.展开更多
Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol(PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M_n was about 430. Lique...Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol(PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M_n was about 430. Liquefied products(LBPP) could be used as raw materials for polyurethane by reacting with 4, 4'-diphenylmethane diisocyanate(4, 4'-MDI) and PEG400 to synthesize liquefied product-based polyurethane(LBPP-PU) adhesive. To analyze in depth the creation of urethane linkage among LBPP, PEG400 and 4, 4'-MDI, factors which had effects on the residue content were all investigated. They were characterized by FT-IR and TG. The shear strength of LBPP-PU adhesive was improved when decreasing the percentage of the substitution of PEG400 by LBPP. The adhesive strength was obtained from T-peel of aspen/polyurethane adhesive joints, and the maximum lap shear strength(4.40 MPa) was obtained when 16.70% of LBPP was added to the LBPP & PEG400 system.展开更多
文摘MXenes have promises in myriad applications by virtue of two-dimensional nature and adjustable functional groups.To achieve the applications,MXenes are always first prepared in the form of aqueous suspension.However,fast degradation caused by the attack of dissolved oxygen and water molecules is the main obstacle to the application of MXenes.It has come to light that the degradation preferentially takes place at defective sites and edges where defects enrich.To tackle this problem and increase the stability,herein,using Ti_(3)C_(2)T_(x)MXene as a model material,we report a simple yet efficient strategy for long term storage of MXene suspension by introducing glycerol,a typical polyhydric alcohol.The effectiveness of the strategy is evidenced by structural compositional and morphological investigations.Glycerol protects the defective sites of MXene flakes through restricting water and/or oxygen molecules from reactive sites.This is supported by ab initio molecular dynamics simulations that form hydrogen bonds between MXene and glycerol molecules just over defective sites.Following this mechanism,other polyhydric alcohols,such as ethylene glycol and propylene glycol,are also effective in stabilizing Ti_(3)C_(2)T_(x)MXene suspension.The strategy based on polyhydric alcohols has the potential to be extended to other MXenes,solving the most urgent challenge in the field of MXene engineering.
基金Funded by the National Science Foundation of China(No.51263006)the Ministry of Education Ph D Advisor Class Special Fund(No.20134601110004)+2 种基金the Hainan Province of Key Projects(ZDXM20130086)the Hainan Province International Science and Technology Cooperation Specific(No.KJHZ2014-02)the Hainan Province Natural Science Foundation(No.314074)
文摘Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol(PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M_n was about 430. Liquefied products(LBPP) could be used as raw materials for polyurethane by reacting with 4, 4'-diphenylmethane diisocyanate(4, 4'-MDI) and PEG400 to synthesize liquefied product-based polyurethane(LBPP-PU) adhesive. To analyze in depth the creation of urethane linkage among LBPP, PEG400 and 4, 4'-MDI, factors which had effects on the residue content were all investigated. They were characterized by FT-IR and TG. The shear strength of LBPP-PU adhesive was improved when decreasing the percentage of the substitution of PEG400 by LBPP. The adhesive strength was obtained from T-peel of aspen/polyurethane adhesive joints, and the maximum lap shear strength(4.40 MPa) was obtained when 16.70% of LBPP was added to the LBPP & PEG400 system.
