In the present study,the thermal,mechanical,and biological properties of xAg/Ti-30Ta(x=0,0.41,0.82 and 2.48 at%)shape memory alloys(SMAs)were investigated.The study was conducted using optical and scanning electron mi...In the present study,the thermal,mechanical,and biological properties of xAg/Ti-30Ta(x=0,0.41,0.82 and 2.48 at%)shape memory alloys(SMAs)were investigated.The study was conducted using optical and scanning electron microscopy(SEM),X-ray diffractometry(XRD),compression test,and shape memory testing.The xAg/Ti-Ta was made using a powder metallurgy technique and microwave-sintering process.The results revealed that the addition of Ag has a significant effect on the pore size and shape,whereas the smallest pore size of 11μm was found with the addition of 0.41 at%along with a relative density of 72%.The fracture stress and strain increased with the addition of Ag,reaching the minimum values around 0.41 at%Ag.Therefore,this composition showed the maximum stress and strain at fracture region.Moreover,0.82 Ag/Ti-Ta shows more excellent corrosion resistance and biocompatibility than other percentages,obtaining almost the same behaviour of the pure Ti and Ti-6Al-4V alloys,which can be recommended for their promising and potential response for biomaterial applications.展开更多
Herein,a facile and highly efficient synthetic method to prepare organic photothermal materials with high photo-stability and outstanding photothermal performance is reported.Through direct polymerization of commercia...Herein,a facile and highly efficient synthetic method to prepare organic photothermal materials with high photo-stability and outstanding photothermal performance is reported.Through direct polymerization of commercial aromatic monomers in the presence of anhydrous aluminium chloride and dichloromethane,four kinds of conjugated microporous polymers(CMPs)were obtained.Detailed structural analysis confirmed that the resultant CMPs possessed abundant micropores with an extendedπ-conjugated skeleton.Under near-infrared(NIR)light irradiation(808 nm,1.0 W cm−2),all the CMPs showed fast heating-up behavior with their maximum temperatures higher than 150℃.Moreover,the efficiency of photothermal conversion(η)of the CMPs was found to increase linearly with the increase in the number of conjugated benzene rings within the monomer.Poly-TPE from tetraphenylethylene(TPE)and Poly-TP from o-terphenyl(TP)showed highηvalues of over 47%.Poly-TPE was additionally used as a photothermal filler to remotely and spatially control the shape recovery of thermal-sensitive shape memory polymers(SMPs),while its introduction(1 wt%)had little influence on the thermal and mechanical properties of the polymer matrixes.Owing to their excellent NIR photothermal performance as well as a one-step synthetic preparation,these CMPs may be promising photothermal materials for practical applications.展开更多
In this work,azobenzene-containing polyurethane liquid crystal networks(PULCN(AZO)s)were synthesized using a one-pot strategy to demonstrate excellent two-way free-standing thermo-/photo-responsive shape memory effect...In this work,azobenzene-containing polyurethane liquid crystal networks(PULCN(AZO)s)were synthesized using a one-pot strategy to demonstrate excellent two-way free-standing thermo-/photo-responsive shape memory effects.Based on the step-growth nature of hydroxyls and isocyanates,the architectures of the networks were adjusted by controlling the stoichiometries of chemical materials.A uniform monodomain sample was prepared by external stress relaxation via a reversible addition reaction of a dynamic carbamate bond.Two independent transition temperatures assigned to glass transition temperature/melting temperature and liquid crystal phase transition temperature were employed to thermally trigger triple shape memory effects and two-way autonomous actuation.In addition,taking advantage of the trans-cis photoisomerization of azobenzene,the programmed network showed a reversible bending and unbending shape change upon irradiation by visible light at450 and 550 nm,respectively.Coupling the autonomously thermo-induced contraction/extension actuation and reversible photo-induced bending/unbending behaviors of PULCN(AZO)s in one system will expand their potential applications in emerging multifunctional devices.展开更多
基金Project(Q.J130000.2524.12H60)supported by the Ministry of Higher Education of Malaysia and Universiti Teknologi Malaysia。
文摘In the present study,the thermal,mechanical,and biological properties of xAg/Ti-30Ta(x=0,0.41,0.82 and 2.48 at%)shape memory alloys(SMAs)were investigated.The study was conducted using optical and scanning electron microscopy(SEM),X-ray diffractometry(XRD),compression test,and shape memory testing.The xAg/Ti-Ta was made using a powder metallurgy technique and microwave-sintering process.The results revealed that the addition of Ag has a significant effect on the pore size and shape,whereas the smallest pore size of 11μm was found with the addition of 0.41 at%along with a relative density of 72%.The fracture stress and strain increased with the addition of Ag,reaching the minimum values around 0.41 at%Ag.Therefore,this composition showed the maximum stress and strain at fracture region.Moreover,0.82 Ag/Ti-Ta shows more excellent corrosion resistance and biocompatibility than other percentages,obtaining almost the same behaviour of the pure Ti and Ti-6Al-4V alloys,which can be recommended for their promising and potential response for biomaterial applications.
基金the National Natural Science Foundation of China(51503231 and 21374136)Guangdong Innovative and Entrepreneurial Research Team Program(2013S086)the Fundamental Research Funds for the Central Universities(17lgjc03 and 18lgpy04)。
文摘Herein,a facile and highly efficient synthetic method to prepare organic photothermal materials with high photo-stability and outstanding photothermal performance is reported.Through direct polymerization of commercial aromatic monomers in the presence of anhydrous aluminium chloride and dichloromethane,four kinds of conjugated microporous polymers(CMPs)were obtained.Detailed structural analysis confirmed that the resultant CMPs possessed abundant micropores with an extendedπ-conjugated skeleton.Under near-infrared(NIR)light irradiation(808 nm,1.0 W cm−2),all the CMPs showed fast heating-up behavior with their maximum temperatures higher than 150℃.Moreover,the efficiency of photothermal conversion(η)of the CMPs was found to increase linearly with the increase in the number of conjugated benzene rings within the monomer.Poly-TPE from tetraphenylethylene(TPE)and Poly-TP from o-terphenyl(TP)showed highηvalues of over 47%.Poly-TPE was additionally used as a photothermal filler to remotely and spatially control the shape recovery of thermal-sensitive shape memory polymers(SMPs),while its introduction(1 wt%)had little influence on the thermal and mechanical properties of the polymer matrixes.Owing to their excellent NIR photothermal performance as well as a one-step synthetic preparation,these CMPs may be promising photothermal materials for practical applications.
基金supported financially by the National Natural Science Foundation of China(51773131 and 51721091)the Fundamental Research Funds for the Central Universities。
文摘In this work,azobenzene-containing polyurethane liquid crystal networks(PULCN(AZO)s)were synthesized using a one-pot strategy to demonstrate excellent two-way free-standing thermo-/photo-responsive shape memory effects.Based on the step-growth nature of hydroxyls and isocyanates,the architectures of the networks were adjusted by controlling the stoichiometries of chemical materials.A uniform monodomain sample was prepared by external stress relaxation via a reversible addition reaction of a dynamic carbamate bond.Two independent transition temperatures assigned to glass transition temperature/melting temperature and liquid crystal phase transition temperature were employed to thermally trigger triple shape memory effects and two-way autonomous actuation.In addition,taking advantage of the trans-cis photoisomerization of azobenzene,the programmed network showed a reversible bending and unbending shape change upon irradiation by visible light at450 and 550 nm,respectively.Coupling the autonomously thermo-induced contraction/extension actuation and reversible photo-induced bending/unbending behaviors of PULCN(AZO)s in one system will expand their potential applications in emerging multifunctional devices.
