Hydrosilylated allyl-silica hybrid monolithic columns

Organic-inorganic silica hybrid monolithic columns were synthesized containing an allyl pendant. The ally-monolithic columns were then modified via hydrosilylation reactions to introduce further surface functionalization. The approach was demonstrated by functionalizing allyl-monolytic columns with n-octyl-dimethylsilane (C₈-DMS) and benzyl-dimethylsilane (benzyl-DMS). Of the surface available ally groups on the hybrid monolith (i.e., 6.79 μmol/m²), 31.3% reacted via hydrosilylation, resulting in a C₈ surface coverage of 2.12 μmol/m². When using benzyl-DMS, a surface coverage of 1.95 μmol/m² was calculated for the benzyl groups. The retentivity of the hybrid monolithic columns increased considerably after the hydrosilylation, as monitored by CLC and CEC. The largest increase in retention was observed with the C₈ modified monolith. The hybrid monolithic columns showed higher hydrolytic stability than monolithic columns prepared by the conventional silanoxane bonding of alkyl chlorosilanes modification. The ally-monolithic column provides a platform for the fabrication of hybrid monoliths that can be conveniently modified by means of hydrosilylation, tailoring the surface of the material. The approach is a promising method to prepare hybrid monolithic columns with versatile stationary phases in a simple and efficient manner.