Hydrophilic-modified UVA such as the hydroxyphenyl-benzotriazole
BTZ-PEG (see Fig. 1) can be
incorporated into WB systems if the polarity is
sufficiently high. However, ionic or hydrophilic modifications
of existing products are not ideal because the
choice of suitable products is limited by the chemistry
and there is still a need for cosolvents for adequate
incorporation which clearly contributes to greater
VOC contents of the formulation. Moreover, by
making a substance ionic/hydrophilic, its photopermanence
can be negatively influenced because of the
increased water sensitivity with migration and leaching
effects.