Preparation and Characterization of Silanized Cardboard via Inverse Gas Chromatography and Complementary Analytical Techniques

Abstract

Three silanized cardboard samples, MeSi-CB, Me₂Si-CB, and MePhSi-CB were prepared by reacting bare cardboard with chlorosilanes with different substituents, trichloromethylsilane (TCMS), dichlorodimethylsilane (DCDMS), and dichloromethylphenylsilane (DCMPS), respectively, in toluene. Fourier transform infrared spectroscopy confirmed the formation of siloxane condensation in the silanized cardboard samples. Silicon content, specific surface area (SSA), and pore volume measurements indicated that TCMS was a more efficient silanizing agent for producing highly branched siloxane networks on cardboard than DCDMS and DCMPS. Inverse gas chromatography (IGC) was used to measure the molar adsorption enthalpy (∆H_m) of various hydrocarbons, dispersive surface energy (${\gamma }_{\mathrm{s}}^{\mathrm{dis}}$), and acid–base properties of the silanized cardboard samples. IGC data showed that the ${\gamma }_{\mathrm{s}}^{\mathrm{dis}}$ of the silanized cardboard samples increased due to the formation of siloxane condensation and the reduction of hydroxyl groups. In addition, the increase in the ${\gamma }_{\mathrm{s}}^{\mathrm{dis}}$ also resulted from siloxane cross-linking and the formation of highly branched siloxane networks with increased SSA, which led to a “double field effect” via simultaneous interactions with adsorbed hydrocarbons. This was particularly noticeable in MeSi-CB, in which silanization was conducted using TCMS with three condensation sites. The SSA and ${\gamma }_{\mathrm{s}}^{\mathrm{dis}}$ of MeSi-CB significantly increased and the ∆H_m of the hydrocarbons decreased after silanization. However, the SSA, ${\gamma }_{\mathrm{s}}^{\mathrm{dis}}$, and ∆H_m of the hydrocarbons of Me₂Si-CB and MePhSi-CB did not change much presumably because both DCDMS and DCMPS contain two condensation sites and were less effective in siloxane cross-linking.