(a) the substituted silsesquioxane-based particles have a volume-average size of 5 nanometers or more and at the same time less than 500 nanometers as determined by dynamic light scattering; and

(b) the substituted silsesquioxane-based particles are substituted only with one or more than one moiety selected from a group consisting of alkyl, aryl, hydroxyl, trace amounts of alkoxy and combinations thereof and contain 50 mole-percent or less hydroxyl substitution in the form silanol functionalities relative to moles of substituted silsesquioxane-based particle as determined by infrared spectroscopy;

M_aD_bT_cQ_d  (I)

where: M is R₃Si(OR′)_wO_(1-w)/2, D is R₂Si(OR′)_xO_(2-x)/2, T is RSi(OR′)_yO_(3-y)/2, Q is Si(OR′)_zO_(4-z)/2, R is independently in each occurrence selected from a group consisting of alkyl and aryl, R′ is in each occurrence selected from a group consisting of alkyl and hydrogen, “w” has a value in a range of zero to less than one, “x” has a value in a range of zero to less than two, “y” has a value in a range of zero to less than three and “z” has a value in a range of zero to less than four wherein the selection of R′, “w”, “x”, “y” and “z” are such that the hydroxyl concentration resulting from R′ being hydrogen is 50 mole-percent or less as determined by infrared spectroscopy and the alkoxy concentration resulting from R′ being alkyl is such that there is at most a trace amount of alkoxy, “a” is a value of zero or greater and 0.4 or less: “b” is a value of zero or greater and 0.3 or less; “e” has a value of 0.5 or greater and 1.0 or less: “d” has a value of zero or greater and 0.1 or less and the sum of “a”, “b”, “c” and “cd” is 1.0.