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Surface photografting initiated by benzophenone in water and mixed solvents containing water and ethanol
Author(s) -
Li Guangwu,
He Guanyang,
Zheng Yunan,
Wang Xiaoxiao,
Wang Huiliang
Publication year - 2011
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/app.34683
Subject(s) - photografting , benzophenone , solvent , monomer , polymer chemistry , acrylic acid , polyethylene , chemistry , methacrylic acid , materials science , nuclear chemistry , organic chemistry , polymer
Photografting reactions are usually carried out in organic solvents due to the water insoluble nature of photoinitiators such as benzophenone (BP). This work reports the effect of water and mixed solvents containing water and ethanol on the surface photografting of methacrylic acid (MAA) onto polyethylene initiated by BP. The percent grafting increased with the increase of water volume ratio in the mixed solvent, and BP showed the highest photoinitiation efficiency when dissolved in pure water solvent. Effects of BP concentration, monomer concentration, and monomer type on photografting were studied. The percent grafting showed the maximum at a lower BP concentration (0.20 mol/mol %) in pure water solvent than that (0.60 mol/mol %) in the mixed solvent with 90 v/v % water. The percent grafting first increased with the increase of monomer concentration till 3 mol L −1 and then decreased. Acrylic acid (AA) could also be photografted onto polyethylene by BP in the mixed solvents. UV–visible spectroscopic examinations revealed that the λ max of π–π* transitions of BP red shifted as the increase of the water volume ratio, i.e., the polarity of the solvent. The excitation of BP in solvents with a higher polarity under UV irradiation requires less energy, so the photografting initiated by BP is easier to occur. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012