New Hybrid Organic/Inorganic Polysilsesquioxane-Silica Particles as Sunscreens

Stephanie H. Tolbert, Peter D. McFadden, Douglas A. Loy

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Effectiveness of organic sunscreens is limited by phototoxicity and degradation. Both of which can be significantly reduced by encapsulation in hollow particles or covalent incorporation into the solid structure of particles, but direct comparisons of the two methods have not been reported. In this study, physical encapsulation and covalent incorporation of sunscreens were compared with 1 mol % salicylate and curcumeroid sunscreens. 2-Ethylhexyl salicylate was physically encapsulated in hollow silica nanoparticles prepared by oil-in-water (O/W) microemulsion polymerizations (E-Sal). Some of these particles were coated with an additional shell or cap of silica to reduce leaking of sunscreen (cap-E-Sal). Covalent incorporation involved co-polymerizing tetraethoxysilane (TEOS) with 0.2 mol % of new salicylate and curcuminoid sunscreen monomers with triethoxsilyl groups. Particles were prepared with the salicylate attached to the silica matrix through single silsesquioxane groups (pendant; P-Sal) and two silsesquioxane groups (bridged; B-Sal). Particles based on a new curcuminoid-bridged monomer were also prepared (B-Curc). Sunscreen leaching, photodegradation, and sunscreen performance were determined for the E-Sal, cap-E-Sal, P-Sal, B-Sal, and B-Curc particles. Covalent attachment, particularly with bridged sunscreen monomers, reduced leaching and photodegradation over physical encapsulation, even with capping.

Original languageEnglish (US)
Pages (from-to)3160-3174
Number of pages15
JournalACS Applied Materials and Interfaces
Issue number5
StatePublished - Feb 17 2016


  • hybrid organic inorganic particles
  • pendant versus bridged polysilsesquioxanes
  • sunscreen

ASJC Scopus subject areas

  • Materials Science(all)


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