Mechanism of Photolytic Decomposition of N-Halamine Antimicrobial Siloxane Coatings

Kocer H. B., Akdag A., Worley S. D., Acevedo O., Broughton R. M., Wu Y.

ACS APPLIED MATERIALS & INTERFACES, cilt.2, sa.8, ss.2456-2464, 2010 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 2 Sayı: 8
  • Basım Tarihi: 2010
  • Doi Numarası: 10.1021/am100511x
  • Dergi Adı: ACS APPLIED MATERIALS & INTERFACES
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.2456-2464
  • Anahtar Kelimeler: antimicrobial materials, siloxanes, N halamines, UVA irradiation, decomposition products, GAS-PHASE REACTIONS, CHLORO-AMIDES, DISINFECTION, WATER, HALOGENOALKYLSILANES, REARRANGEMENT, CHEMISTRY, POLYMERS, BOND
  • Orta Doğu Teknik Üniversitesi Adresli: Hayır

Özet

Generally, antimicrobial N halamine siloxane coatings can be rehalogenated repetitively upon loss of their biocidal efficacies, a marked advantage over coatings containing other antimicrobial materials. However, the N halamine materials tend to slowly decompose upon exposure to ultraviolet irradiation as in direct sunlight. In this work the mechanism of photolytic decomposition for the N halamine siloxanes has been studied using spectroscopic and theoretical methods. It was found that the N chlorinated coatings slowly decomposed upon UVA irradiation, whereas the unhalogenated coatings did not. Model compound evidence in this work suggests that upon UVA irradiation, the N-Cl bond dissociates homolytically, followed by a Cl radical migration to the alkyl side chain connected to the siloxane tethering group. An alpha and/or beta scission then occurs causing partial loss of the biocidal moiety from the surface of the coated material thus precluding complete rechlorination. NMR, FTIR, GCMS, and computation at the DFT (U)B3LYP/6-311++G(2d,p) level of theory have been employed in reaching this conclusion.