A blue fluorescence-emitting hyperbranched polysiloxane simultaneously containing hydroxyl and epoxy groups (HPHEp) has been developed through one-step A2 + B3 melt polycondensation between methoxyl groups of (3-glycidyloxypropyl)trimethoxysilane (A-187) and hydroxyl groups of neopentyl glycol under catalyst-free conditions. The emission intensity of the HPHEp in ethanol solution continuously arises in pace with raising its concentration, and the brightest luminescence is observed even in the 100% solid state. Studies show that the aggregation of oxygen-rich heteroatoms from the hydroxyl and epoxy groups is assigned to the luminous source. Intriguingly, the HPHEp displays reinforced photoluminescence after polyetherification by 20 wt% polyether amine M2070; nevertheless, the modified polymer represents diminished emission intensity along with increasing the polyether content. Thus, this investigation offers a new methodology of designing photoluminescent materials. [ABSTRACT FROM AUTHOR]