Styrene Shape-Memory Polymer And Its Study Of Optical And Magnetic Actuation

Shape memory polymer (SMP), a new type of smart materials, has lot of advantages, such as large reversible deformation, easy molding, adjustable deformation temperature and low cost of production. However, thermally induced SMP typically need a force in the process of pre-deformation, and its response need hot medium to drive the initial shape. The low driving efficiency and difficult implementation limit its applications. In this thesis, a series of styrene SMP were synthesized by free radical copolymerization, which was drived by infrared laser and magnetic-heat.Firstly, copolymerization was employed to prepare a series of styrene SMP through the comonomer content and crosslinker control. The synthesized styrene SMP showed good mechanical properties and excellent shape memory performances. When the drived temperature was equal to or higher than the glass transition temperature (Tg), the shape recovery rate of the styrene SMP was greater than 95%, and the shape recovery speed was quickly. This styrene SMP was an amorphous polymer and its chemical structures was stable. It had an adjustable Tg from 60oC to 95 oC, and high thermal decomposition temperature. In addition, rubber elastic theory was used to analyze the entropy change in the process of shape recovery. It demonstrated that the shape memory effect was due to the entropy increase. Based on the theory of thermodynamics and entropy elasticity theory, the relationships between entropy change and cross-linking density of network were structured qualitatively. Results showed that, with the crosslinking density of network increased, the shape recovery trend was significantly and shape memory effect was more obvious.Secondly, theγ-ray radiation resistant capability was studied. The synthesized styrene SMP showed better thermal properties, dynamic mechanical properties and thermal stability at a dose of 1×10~5Gy ofγ-ray radiation. When the radiation dose increased to 1×10~6Gy, the crosslink density became lower, while the dynamic mechanical properties, glass transition temperature, static mechanical properties and shape memory behavior did not have significantly changes. However, when the irradiation dose of the gamma ray was increased to 5×10~6Gy, the glass transition temperature, thermal stability and dynamical properties of the SMP were significantly decreased. Therefore, it was concluded that the prepared styrene SMP could bear the irradiation of gamma ray under 1×10~6Gy. And the anti-irradiation properties of the polymer would be increased with the addition of cross linking agent, and be decreased with the addition of monomers.Finally, the light-driven shape memory effect of the styrene SMP was investigated, included the optical properties of polymer, glass transition temperatures and thermodynamic behaviors. In addition, the magnetic-heat driving approach for styrene SMP was also demonstrated by addition of nickel powder into styrene SMP. The surface of nickel powder adsorbed coupling agent molecules after chemical attachment. During the curing process, the nickel powder surface of the coupling agent and resin matrix molecules could react to form the chemical connection. In this way, the composite storage modulus and glass transition temperature increased with the amount of nickel powder. In addition, the response speed of this SMP composite would decrease when the contents of Ni powder increased.