title: Predicting the Conditions for Homeotropic Anchoring of Liquid Crystals at a Soft Surface. 4-n-Pentyl-4'-cyanobiphenyl on Alkylsilane Self-Assembled Monolayers.
abstract: We have studied, using atomistic molecular dynamics simulations, the alignment of the nematic liquid-crystal 4-n-pentyl-4'-cyanobiphenyl (5CB) on self-assembled monolayers (SAMs) formed from octadecyl- and/or hexyltrichlorosilane (OTS and HTS) attached to glassy silica. We find a planar alignment on OTS at full coverage and an intermediate situation at partial OTS coverage because of the penetration of 5CB molecules into the monolayer, which also removes the tilt of the OTS SAM. Binary mixtures of HTS and OTS SAMs instead induce homeotropic (i.e., perpendicular) alignment. A comparison with the existing experimental literature is provided.
authors.affiliation: Dipartimento di Chimica Industriale "Toso Montanari" Università di Bologna , viale Risorgimento 4, IT-40136 Bologna, Italy.
authors.forename: Otello Maria
authors.identifier: http://orcid.org/0000-0001-7815-6636
authors.initials: OM
authors.lastname: Roscioni
authors.affiliation: Dipartimento di Chimica Industriale "Toso Montanari" Università di Bologna , viale Risorgimento 4, IT-40136 Bologna, Italy.
authors.forename: Luca
authors.identifier: http://orcid.org/0000-0001-9227-1059
authors.initials: L
authors.lastname: Muccioli
authors.affiliation: Dipartimento di Chimica Industriale "Toso Montanari" Università di Bologna , viale Risorgimento 4, IT-40136 Bologna, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Zannoni
keywords: anchoring coefficient; homeotropic alignment; liquid crystals; molecular dynamics; organic functional materials; self-assembled monolayers; surface science; thin films