title: Delicate modification of poly(dimethylsiloxane) ultrathin film by low-energy ion beam treatment for durable intermediate liquid crystal pretilt angles.
abstract: Long-term stability of intermediate liquid crystal pretilt angles on a poly(dimethylsiloxane) (PDMS) ultrathin film grafted onto a surface was realized simply and easily via low-energy ion beam (IB) treatment. The composition and surface energy of the thin film could be controlled by varying the low-energy IB treatment. This treatment results in the permanent chemical modification of the film surface, converting it from organic PDMS to a mixed layer of organic PDMS and inorganic silica. The partial transformation of a PDMS surface gives rise to the control of the pretilt angle via the formation of the inhomogeneous surface and the stabilization of the pretilt angle via the cross-linking reaction of broken chemical bonds through IB irradiation. As a result, a continuous variation of pretilt angles that maintained their initial value with long-term stability was obtained. Thus, the unique chemical transformation of the PDMS surface using IB treatment may allow for the production of durable intermediate liquid crystal pretilt angles.
authors.affiliation: Department of Materials Science and Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749, Korea.
authors.forename: Byoung Har
authors.initials: BH
authors.lastname: Hwang
authors.forename: Chu Ji
authors.initials: CJ
authors.lastname: Choi
authors.forename: Min Kyoung
authors.initials: MK
authors.lastname: Jo
authors.forename: Jong Bok
authors.initials: JB
authors.lastname: Kim
authors.forename: Hae Min
authors.initials: HM
authors.lastname: Choe
authors.forename: Soo Sang
authors.initials: SS
authors.lastname: Chae
authors.forename: Youn Sang
authors.initials: YS
authors.lastname: Kim
authors.forename: Hong Koo
authors.initials: HK
authors.lastname: Baik
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D008567:Membranes, Artificial; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004129:Dimethylpolysiloxanes; D008567:Membranes, Artificial; C013830:baysilon; D012822:Silicon Dioxide