Interaction between poly (ethylene oxide) and silica nanoparticles in dilute solutions

A mixed system that includes poly(ethylene oxide) (PEO) and silica (SiO₂) nanoparticles is prepared using two mixing methods. The interaction between PEO and the SiO₂ nanoparticles in the dilute basic solution is investigated using the dynamic light scattering (DLS) and isothermal titration calorimetry (ITC) techniques. The DLS results show qualitatively that SiO₂ nanoparticles interact with both random coils and aggregates of PEO through hydrogen bonding, and PEO-SiO₂ complexes are formed. The degree of disaggregation of aggregates of PEO is readily adjusted by changing the concentration of SiO₂ nanoparticle suspensions. Moreover, the ITC results also certify quantitatively the interaction between PEO and SiO₂ nanoparticle, and give the evidence of formation of PEO-SiO₂ complex.