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Here what I found about modification of filter paper with chlorine-substituted octadecylsilane:

Cellulose filter paper was cut into the rectangular strips (1 cm × 4 cm) with a pair of scissors. The tapes were washed with acetone and dried at room temperature. The tape was transferred to a 2-mL screw cap polypropylene vial containing 1.5 mL 10% (v/v) of octadecyltrichlorosilane (or diphenyldichlorosilane) in chloroform and 0.1 mL pyridine. Reaction was performed at room temperature for 12 h. The tape was then washed with chloroform and acetone and dried at room temperature. Here is the link:

Article Chemically Modified Cellulose Paper as a Thin Film Microextr...

As for the octadecylsilane, octadecylsilane (ODS)-coated cellulose-based filter paper (OCFP) was prepared via a thermally induced silane dehydrocoupling reaction between the hydroxide groups (O– H) of cellulose-based filter paper (CFP) and the trihydridosilane (Si–H3) of ODS (Figure 1b). CFP was immersed in a solution of ODS in normal hexane (n-hexane) for 24 h at 80 ◦C (ODS:n-haxane = 1:2 (v/v), optimized ratio). Here is the link:

https://www.mdpi.com/1996-1944/14/19/5775

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