摘要
Particle hydrogel composite(PHC)combines the characteristics of at least two mat erials and has pot ential applications in many fields.Different functions require the particle size to range from nanometer to millimeter,which has a noticeable effect on the mechanical properties of the hydrogel composites.In this paper,the mechanical properties of silica-inlaid PAAM hydrogel are measured with various particle diameters from 75 nm to 50|im.Experimental results show no obvious size effect on the mechanical properties of PHC when the particle diameter falls in micron scale.However,as the particle size decreases to nanoscale,the modulus of the PHC begins to increase rapidly.The size-irrelevant moduli and stress fields of PHCs with random and uniform particle distributions under different loading conditions are obtained based on the finite element method.Meanwhile,the toughening mechanism and the failure of the PHC are investigated.The size-irrelevant modulus of the PHC is also predicted by the equivalent inclusion theory.Finally,the interaction between the hydrogel polymer chains and the particles is described from the microscopic point of view,requiring the nanoscale size-dependent theory and new experimental approach to further explore the mechanical proper ties of PHC.