Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.
Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (<20nm thick) were mainly investigated by atomic force microscopy. Surface chemical analysis of the ultrathin films annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time.
Department of Polymer Materials and Engineering, College of Materials Science and Engineering, Harbin University of Science and Technology, 4 Linyuan Road, Harbin 150040, PR China.
Changchun
C
Huang
Department of Polymer Materials and Engineering, College of Materials Science and Engineering, Harbin University of Science and Technology, 4 Linyuan Road, Harbin 150040, PR China. Electronic address: gywen@hrbust.edu.cn.
Gangyao
G
Wen
Department of Polymer Materials and Engineering, College of Materials Science and Engineering, Harbin University of Science and Technology, 4 Linyuan Road, Harbin 150040, PR China.
Jingdan
J
Li
Department of Polymer Materials and Engineering, College of Materials Science and Engineering, Harbin University of Science and Technology, 4 Linyuan Road, Harbin 150040, PR China.
Tao
T
Wu
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, PR China.
Lina
L
Wang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, PR China.
Feifei
F
Xue
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, PR China.
Hongfei
H
Li
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, PR China.
Tongfei
T
Shi
Atomic force microscopy; Block copolymer; Dewetting; Solvent vapor annealing; X-ray photoelectron spectroscopy