| The relationship between the structure and properties of materials(constitutive relationship)has always become the "ultimate proposition" for materials scientists and researchers.In the information era,materials are also developing towards "Intelligence,Information and Programmable".Considering about all the stimulus sources(also known as energy source),light has irreplaceable properties such as non-contact,penetrating,time-domain controllable and highly quantumized.These properties do not exist simultaneously in common energy sources: acoustic,electrical,magnetic,thermal,and force.All mentioned above makes light responsive materials a kind of smart materials with promising potential for development.The main research of this topic is as follows.(1)Highly oriented polyimide nanofibre-reinforced photoresponsive liquid crystal polymers were prepared,and interfaces were enhanced by supramolecular hydrogen bonding.Since the existence of hydroxyl groups in the side chains of the azobenzene-containing liquid crystal polymers and the polyimide nanofibres.The hydrogen bonding positions were also precisely located.The composite films exhibit a hierarchical structure similarity with that of natural dragonfly wings,and showed high modulus of elasticity(1.64 GPa),commuted modulus(72.8 GPa)and nano-hardness(4.5 GPa)which were 20-30 times higher than natural dragonfly wings.The enhanced mechanical properties allow the composite films to exhibit a unique photoresponsive behaviour,i.e.a fast-responding photo-induced deformation.Furthermore,by varying the pulsed light irradiation,the vibration frequency and the bending angle of the composite films can be continuously tuned over 0.1-5 Hz,1.5°-15.8°,and it is demonstrated that this motion obeyed an unconventional lightdriven mechanism that incorporated rheological changes in azobenzene liquid crystal macromolecules.It is also demonstrated that using differential-integral processes in anisotropic materials could achieve controllable magnitude of micro properties.(2)A series of linear copolymers containing azobenzene monomers and low glass transition temperature monomers were synthesized by atom transfer radical polymerization(ATRP)with different copolymerization ratios.The rheological properties of the azobenzene linear polymers were investigated in the trans and cis states by means of dielectric relaxation spectroscopy and rotational rheometry.Then,some mathematical descriptions were also made with the aid of the classical "Kelvin-Wogart" and "Maxwell" spring-bound muco-pot models.A new model of "spring-bonded muco-pot" is used to describe the coupling between the liquid crystal motion of trans azobenzene and the main chain,which establishes a theoretical basis for the subsequent description of its "photo-responsive rheology",and an attempt is made to explain the rheological properties of azobenzene linear liquid crystal polymers by corresponding microscopic motions at different states,frequencies and temperatures.(3)In the implementation of photothermal energy storage materials at the crystal scale,we propose a method to increase the energy density by introducing weak supramolecular interactions-"Cation-π" interactions into the phase change azo-benzene photothermal fuel(Azo-STF)system.Notably,the energy density of Azo-STF can be increased 24.7 % at a low cation loading(1.96mol%).When phototriggered,it has a weight power density of approximately56.91 W·h/kg,and producing an 8 ℃ temperature increasement in ambient.Furthermore the mechanism of the high performance induced by this interaction is revealed at the molecular and crystal scale. |
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