Formation of Interconnected Elastomeric Phase Unevenly Jammed by Nanosilica in the Plastic Matrix during Melt Processing

Simultaneously regulating the phase morphology and dispersion of nanoparticles in multicomponent polymeric materials is a highly desired but challenging task. In this work, we investigate the structural development of the PLLA/EGMA/SiO2 (polylactide/ethylene-acrylic ester-glycidyl methacrylate terpolymer/nanosilica) nanocomposites during melt compounding. By taking advantage of the melt temperature differences of PLLA and EGMA and their different affinity with SiO2, polymer blend nanocomposites with different morphologies have been prepared by varying the mixing sequences. The materials with an interconnected EGMA phase unevenly jammed by SiO2 have been fabricated by simply first blending the SiO2 with the PLLA matrix followed by the incorporation of EGMA in the melt. Such novel structure provides excellent comprehensive mechanical properties with super toughness and high tensile strength. The motion of EGMA-coated nanoparticles promoted the coalescence of neighboring EGMA domains, resulting in interconnected EGMA phases with SiO2 nanoparticles during melt blending. The low interfacial tension and the increasing viscoelasticity of the elastomeric phase prevent the breakup of the EGMA phases and allow the irregularly elongated shape to be stabilized and maintained. This work not only benefits the understanding of the structural evolution in the melt process under shear but also provides a facile yet tangible strategy to tailor the morphology of multicomponent polymer systems.