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Plasma‐polymerized hexamethyldisiloxane films characterized by variable‐energy positron lifetime spectroscopy
Author(s) -
Wang C. L.,
Kobayashi Y.,
Togashi H.,
Kato K.,
Hirotsu T.,
Hirata K.,
Suzuki R.,
Ohdaira T.,
Mikado T.
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19991205)74:10<2522::aid-app21>3.0.co;2-h
Subject(s) - hexamethyldisiloxane , materials science , analytical chemistry (journal) , spectroscopy , plasma polymerization , positron annihilation spectroscopy , polymerization , positron , plasma , monomer , fourier transform infrared spectroscopy , positron annihilation , chemistry , polymer , physics , optics , nuclear physics , organic chemistry , electron , composite material , quantum mechanics
Nanometer‐size holes in plasma‐polymerized thin films were characterized by variable‐energy positron lifetime spectroscopy for the first time. Hexamethyldisiloxane (HMDSiO) was plasma‐polymerized at different discharge powers (30–105 W) and monomer pressures (1.0–4.9 Pa). The positron lifetime spectra of deposited films were collected at positron energies of 1 and 5 keV. All films showed a well‐defined long‐lived component due to pick‐off annihilation of ortho ‐positronium ( o ‐Ps). The o ‐Ps lifetime τ 3 , reflecting the average size of free‐volume holes in the film, increased with an increasing ratio of plasma discharge power, W , and monomer flow rate, F . Based on the empirical relationship between the o ‐Ps lifetime and the cavity radius, hole volumes were estimated to be 0.19–0.36 nm 3 . We also found that the o ‐Ps intensity, I 3 , depends strongly on the same parameter, W / F . Comparison with infrared (IR) absorption spectroscopy data showed that Ps formation is suppressed in films with fewer organic bonds and higher disorder, i.e., those increasingly inorganic in nature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2522–2528, 1999