To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-co...To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.展开更多
A porous,biocompatible,and modifiable chitosan (CS)/poly (vinyl alcohol) (PVA) hybrid membrane, which can be evaluated as wound dressing,has been prepared by lyophilization method and using the low toxicity solvents. ...A porous,biocompatible,and modifiable chitosan (CS)/poly (vinyl alcohol) (PVA) hybrid membrane, which can be evaluated as wound dressing,has been prepared by lyophilization method and using the low toxicity solvents. Experiments illustrated that the moisture regain and porosity rate of polymer blend membranes had the similar variation tendency and got the maximum value at the case of CS/PVA weight ratio of 6∶4. And the value of water vapor transmission rate( WVTR) is conductive to the healing of wound and desirable for the application as a wound dressing.Mechanical performance test of blend membrane showed that the presence of PVA could effectively improve the interaction between CS molecules. The scanning electron microscopy( SEM)photograph confirmed the porous surface on top-layer supported by a macroporous sponge-like sub-layer of this novel type of CS blend membrane. Besides, Fourier transform infrared spectroscopy( FTIR) revealed the facts that the two polymers were physically bended and certain chemical actions took place,which illustrated the good compatibility between them. Differential scanning calorimetry(DSC) results showed that decomposition reaction occurred in CS at about 210℃. Introducing of PVA to CS made the decomposition temperature of blend membrane decrease. The good properties,such as moisture regain,porosity rate,and WVTR,of this kind of CS/PVA blend membranes suggested a potential application as a wound dressing in the future.展开更多
In the rapidly evolving field of wearable electronics,stretchy organic solar cells(OSCs)have emerged as promising candidates for portable power sources,necessitating materials with superior mechanical flexibility.Howe...In the rapidly evolving field of wearable electronics,stretchy organic solar cells(OSCs)have emerged as promising candidates for portable power sources,necessitating materials with superior mechanical flexibility.However,the inherent rigidity of conjugated backbones in top-performance photovoltaic polymers,such as PM6,poses a significant challenge,as it makes photovoltaic films prone to fracture under mechanical strain.Consequently,improving the mechanical properties of these films is a crucial research frontier for advancing stretchable photovoltaic technologies.This tutorial review provides a thorough examination of current strategies aimed at bolstering the mechanical resilience of polymer photovoltaic thin films,elucidated through a selection of pertinent examples leveraging the PM6-based systems.We first explore the prevalent strategy of incorporating third components,including vip polymer donors/acceptors and insulating polymers,to improve stretchability.We then discuss the structural design of PM6 aimed at reducing the backbone rigidity.Additionally,we summarize various predictive models for assessing the mechanical properties of these photovoltaic films.Finally,the future challenges and perspectives for stretchy OSCs are explored.展开更多
文摘To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.
基金Natural Science Foundation of Shanghai,China(No.14ZR1401000)Shanghai University Students Innovation Project of China(No.sh201410255026)National Natural Science Foundation of China(No.51303021)
文摘A porous,biocompatible,and modifiable chitosan (CS)/poly (vinyl alcohol) (PVA) hybrid membrane, which can be evaluated as wound dressing,has been prepared by lyophilization method and using the low toxicity solvents. Experiments illustrated that the moisture regain and porosity rate of polymer blend membranes had the similar variation tendency and got the maximum value at the case of CS/PVA weight ratio of 6∶4. And the value of water vapor transmission rate( WVTR) is conductive to the healing of wound and desirable for the application as a wound dressing.Mechanical performance test of blend membrane showed that the presence of PVA could effectively improve the interaction between CS molecules. The scanning electron microscopy( SEM)photograph confirmed the porous surface on top-layer supported by a macroporous sponge-like sub-layer of this novel type of CS blend membrane. Besides, Fourier transform infrared spectroscopy( FTIR) revealed the facts that the two polymers were physically bended and certain chemical actions took place,which illustrated the good compatibility between them. Differential scanning calorimetry(DSC) results showed that decomposition reaction occurred in CS at about 210℃. Introducing of PVA to CS made the decomposition temperature of blend membrane decrease. The good properties,such as moisture regain,porosity rate,and WVTR,of this kind of CS/PVA blend membranes suggested a potential application as a wound dressing in the future.
基金supported by the Science Fund for Distinguished Young Scholars of Tianjin Municipality(23JCJQJC00240)the National Natural Science Foundation of China(52121002)+1 种基金the Start-up Grant of Peiyang Scholar Program from Tianjin Universitythe Fundamental Research Funds for the Central Universities.
文摘In the rapidly evolving field of wearable electronics,stretchy organic solar cells(OSCs)have emerged as promising candidates for portable power sources,necessitating materials with superior mechanical flexibility.However,the inherent rigidity of conjugated backbones in top-performance photovoltaic polymers,such as PM6,poses a significant challenge,as it makes photovoltaic films prone to fracture under mechanical strain.Consequently,improving the mechanical properties of these films is a crucial research frontier for advancing stretchable photovoltaic technologies.This tutorial review provides a thorough examination of current strategies aimed at bolstering the mechanical resilience of polymer photovoltaic thin films,elucidated through a selection of pertinent examples leveraging the PM6-based systems.We first explore the prevalent strategy of incorporating third components,including vip polymer donors/acceptors and insulating polymers,to improve stretchability.We then discuss the structural design of PM6 aimed at reducing the backbone rigidity.Additionally,we summarize various predictive models for assessing the mechanical properties of these photovoltaic films.Finally,the future challenges and perspectives for stretchy OSCs are explored.
