Effects of Particle-polymer Interactions and Particle-particle Interactions on Mechanical Properties of Polymer Nanocomposites

The inclusion of nanoparticles (NPs) or polymer-grafted nanoparticles (PGNPs) can impart the polymeric materials with enhanced properties in polymer nanocomposites (PNCs). Compared to the traditional polymer materials, the excellent performances of PNCs such as superior mechanical, thermodynamic, and optical properties have become a prominent aspect of scientific research. However, it still remains unclear about the relationship between interfacial interactions and mechanical enhancement in PNCs because the various factors i.e., grafting density s (chains/nm(2)), the chain length of matrix versus the grafted polymer (P/N) and nanoparticle size can complicatedly affect the interfacial characteristics. Understanding the enhancement mechanism of the NPs/PGNPs in PNCs is, therefore, of crucial importance to modulate the properties of PNCs. Based on the successes and failures of the previous study, this review summarizes the mechanism of mechanical enhancement in PNCs, mainly from two perspectives: particle-polymer interaction and particle-particle interaction. According to the different structural and conformation properties in PNCs, these two aspects are discussed in polymer/NPs nanocomposites and polymer/PGNPs nanocomposites, respectively. Strong reinforcement in PNCs inclusion of unmodified NPs is obtained at low NPs contents due to the overlapping of the glassy layer between NPs, and the network structure occurring at high NPs contents can significantly improve the mechanical properties of the polymer/NPs system. The decoration of grafted chains on the NPs surface can remarkably enhance the interfacial interactions between NPs and matrix. Mechanical properties of the grafted system can be affected by the different dispersion states of PGNPs, through controlling s, P/N and NPs size. The particle-particle interaction under different aggregates is the main contribution to the enhancement of the mechanical properties in polymer/PGNPs system. It is anticipated that this review can be helpful to establish the relationship between the microstructure and macroscopic performance in PNCs and to provide guidance on modulating the mechanical properties of PNCs.

Automated summary

This review summarizes the mechanical enhancement mechanism of nanoparticles and polymer in polymer nanocomposites, focusing on particle-polymer interaction and particle-particle interaction. By controlling factors such as grafting density, chain length, and nanoparticle size, the properties of polymer nanocomposites can be modulated effectively.