高分子材料の可塑化・逆可塑化と力学特性制御

抄録

This review discusses strategies for controlling the mechanical properties of polymeric materials through plasticization, anti-plasticization, and photo-induced modifications. Conventional plasticization reduced stiffness by enhancing molecular mobility, whereas anti-plasticization, achieved via small-molecule additives, suppresses local chain motions, resulting in improved elastic modulus while maintaining optical transparency. Detailed analyses revealed that the effectiveness of anti-plasticization depends on molecular dynamics, including additive size and interaction with polymer segments, which can modulate tensile properties such as yield stress and ductility. Additionally, photo-responsive molecules, particularly azobenzene derivatives, enabled dynamic tuning of polymer properties through photo-isomerization of azobenzene units. The photoisomerization enhanced free volume and accelerated polymer chain dynamics, leading to reductions in glass transition temperature and modulus, and even inducing solid–liquid transitions or reversible adhesion under ultraviolet light irradiation. These phenomena were supported by both experimental observations and theoretical modeling, highlighting the potential of photoactive systems for developing smart and reconfigurable polymeric materials. Overall, the studies demonstrated that controlling molecular mobility via chemical additives and external stimuli provides a versatile platform for tailoring stiffness, toughness, and phase behavior of polymers. Such approaches could be helpful for future applications in optical devices, flexible components, and responsive adhesive systems.