Current polymerization methods require the use of initiators or catalysts as auxiliaries to produce free radicals and then facilitate the chain propagation. However, these residual auxiliaries may affect polymer functions and cause toxicity, therefore, a time-consuming purification process is essential. Recently, synchrotron light has been established for generation of radicals in water without catalysts and initiators for polymerization. In this study, we used intensive synchrotron light as a potential tool to synthesize non-linear polyethylene glycol (NLPEG) which exhibits excellent protein-resistant property as compared to linear PEG (LPEG) on the surface. This novel synthesis concept provides an opportunity to produce NLPEG in a very short time (5 min) without employing various chemicals (pollutants) and with minimum environmental concern.