Mesoporous silica nanoparticle is a promising support material for nanometal catalysts for polymer recycling. However, short-chain hydrocarbons may appear as by-products in gaseous form and affect the catalytic process. Avoiding or reducing the gas formation is very important to improve the catalytic ability, which requires a better understanding of interaction kinetics between polymer and nanochannels. To achieve that goal, we utilized UV-vis to study the adsorption of polystyrene (PS) in theta solution (cyclohexane) and desorption in good solution (tetrahydrofuran). From the adsorption experiment in cyclohexane, we found the molecular weight selectivity of the mesoporous particles. Particles with 1.7 nm diameter pores show higher adsorption for lower molecular weight PS while a relatively low selectivity is observed for particles with 2.4 nm and 3.5 nm diameter pores. We also found the adsorption behavior can be described by the Pseudo-Second-Order Model (PSOM). That demonstrated that pore adsorbs small molecular weight PS faster in general cases unless the polymer chain is too large than the pore diameter. Along with the adsorption experiment, the desorption experiment performed in tetrahydrofuran has given more information about the interaction between PS and nanochannels. The result can be illustrated by the First-Order Model (FOM), which indicated smaller molecular weight PS desorb faster when the pore diameter is larger, while the smaller pore did not show a significant difference. From the above experiment, a conclusion can be raised that a larger pore might help reduce the gas formation.

Infiltration kinetics of polymers into nanochannels

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