Synthesis of PDMS-mu-PCL Miktoarm Star Copolymers by Combinations (epsilon) of Styrenics-Assisted Atom Transfer Radical Coupling and Ring-Opening Polymerization and Study of the Self-Assembled Nanostructures

Due to their diverse and unique physical properties, miktoarm star copolymers (mu-SCPs) have garnered significant attention. In our study, we employed alpha-monobomoisobutyryl-terminated polydimethylsiloxane (PDMS-Br) to carry out styrenics-assisted atom transfer radical coupling (SA ATRC) in the presence of 4-vinylbenzyl alcohol (VBA) at 0 C-circle. By achieving high coupling efficiency (chi(c) = 0.95), we obtained mid-chain functionalized PDMS-VBA(m)-PDMS polymers with benzylic alcohols. Interestingly, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analysis revealed the insertion of only two VBA coupling agents (m = 2). Subsequently, the PDMS-VBA(2)-PDMS products underwent mid-chain extensions using epsilon-caprolactone ( epsilon-CL) through ring-opening polymerization (ROP) with an efficient organo-catalyst at 40 C-circle, resulting in the synthesis of novel (PDMS)2-mu-(PCL) (2) mu-SCPs. Eventually, novel (PDMS)(2)- mu-(PCL) (2) mu-SCPs were obtained. The obtained PDMS-mu-PCL mu-SCPs were further subjected to examination of their solid-state self-assembly through small-angle X-ray scattering (SAXS) experiments. Notably, various nanostructures, including lamellae and hexagonally packed cylinders, were observed with a periodic size of approximately 15 nm. As a result, we successfully developed a simple and effective reaction combination (T) strategy (i.e., SA ATRC-T-ROP) for the synthesis of well-defined PDMS mu-PCL mu-SCPs. This approach may open up new possibilities for fabricating nanostructures from siloxane-based materials.