Preparation And Properties Of Cis-1,4 Polybutadiene-Polyethylene Copolymer-based Soft Actuator

Recently,soft actuators based on stimuli-responsive polymers are emerging as a new sort of actuators.In contrast to the traditional rigid actuators,soft actuators present a unique combination of properties including light weight,high flexibility,and high environment adaptability,thereby making them great potential for application in the fields of healthcare,wearable devices,manufacturing,and robotics.In this dissertation,cis-1,4 polybutadiene-polyethylene copolymer(CPB-PE)was designed and utilized as the matrix material,and on the basis of the unique shape memory behaviors of CPB-PE,a series of photoactuators were prepared.The details are listed as follows:1.A high-strain shape memory polymer,CPB-PE semicrystalline copolymer with 2-ureido-4[1H]pyrimidinone(UPy)side groups(UHPB),was synthesized by grafting UPy groups onto CPB and subsequent partial hydrogenation reaction.In the shape memory process,the robustly physical crosslinking via hydrogen bonding through UPy dimerization provided the permanent network,while the crystalline PE segments served as switching phase to afford the temporary network.The broad melting transition ranging from 35.1 to 84.2? allowed this material to achieve multi-shape memory behaviors by choosing two and more switching temperatures within or above the melting transition.The shape memory performance was markedly influenced by the selected critical switching temperature,in other words,the shape fixity and recovery were dependent on the fraction of recrystallized and remelted PE phase during shape fixing and recovery processes,respectively.The two-way shape memory effect under a constant load of this system was also attained by the crystallization-induced elongation and melting-induced contraction of the PE segments in UHPB.Moreover,UHPB exhibited an excellent recoverable high-strain capacity;the shape recovery reached 96.2%at a high strain of 480%.2.Light-driven soft actuators with adaptive shape changes,diverse geometric morphing,and reversible macroscopic movements have gained ever-increasing interest owing to their diverse applications ranging from biomedical to aerospace devices.Herein,we presented a near-infrared(NIR)light stimulated actuator based on cis-1,4 polybutadiene-polyethylene semicrystalline copolymer.In the system,a newly synthesized croconaine dye,2,5-bis[(6-(11-carboxyundecanoate)hexyl-4-carboxylate-piperidylamino)thiophenyl]-croconium,served as both a NIR absorbing agent and cross-linker.Taking advantage of easy processability,two-way shape memory and photothermal effects,the actuators thus-made can undergo intriguing motions in response to NIR irradiation.As a light-fueled crane,this material showed outstanding heavy-lift capability;it can lift an item 11200 times its own weight,and the lifting up/down motions were fully reversible.Besides,the photothermally induced expansion and contraction enabled the actuator with reversible bending motions to serve as other remotely controlled soft robots;a light-driven grasper that can grasp,lift up,lower down,and release an object and a walking robot that can crawl on a ratcheted substrate.3.A near-infrared photoactuator(HCPB-TTC)based on CPB-PE copolymer was prepared via fixing the specific elongated shape and the subsequent UV curing.This actuator exhibited high photothermal conversion efficiency,good actuation magnitude,and excellent actuation stability.On the basis of crystallization induced elongation and melting induced contraction of the crystalline polyethylene segments in the copolymer,the actuator prepared by two-side UV crosslinking of the sample can exhibit elongation/contraction actuation by switching NIR light on and off without the need of an external load.The actuator prepared by the one-side UV crosslinking of the sample curled toward to the un-crosslinked side and displayed large curling amplitude in a relatively high actuation speed.Such actuation behaviors enabled this material to be designed as artificial flowers,artificial flytrap,and biomimetic robotics devices.Moreover,the actuator with wavy deformation was achieved by special local crosslinking of the sample.4.A visible light-responsive actuator(HCPB-PDA)based on CPB-PE/polydopamine nanocomposites was prepared.Upon illumination of the visible light,the curling actuator in a small size(sample dimension:30 mm ×2 mm×0.25 mm)exhibited a large curling amplitude(500 and the sample in a big size(sample dimension:60 mm ×10 mm ×0.25 mm)can form a tubular shape.Additionally,the actuator prepared with a "U " shape can realize a reversible transformation between a "?" shape and a "U" shape upon the switching the visible light on/off The easy preparation of the matrix material and versatility and universality of the visible light makes this actuator great potential to be utilized as large-area visible light-responsive actuators.