Self-healable and reprocessable networks of Poly (propylene oxide) with POSS crosslinked with disulfide bonds


The organic-inorganic networks involving poly(propylene oxide) (PPO) and POSS were synthesized via the in situ crosslinking with disulfide bonds. First, a tri-armed PPO star with amino termini was reacted with 4-(phenoxymethyl)-1,3-dithiolane-2-thione, a cyclic five-membered thiocarbonate to obtain the tri-armed PPO star with mercapto thiourethane termini. In the meantime, 4-aminobutylhepta(3,3,3-trifloroproply) POSS was also reacted with 4-(phenoxymethyl)-1,3-dithiolane-2-thione to obtain a mercapto thiourethane -functionalized POSS macromer. Thereafter, both PPO star and POSS macromer which contained mercapto thiourethane moieties were co-crosslinked via the radical coupling reaction, in which the thiol groups were coupled into disulfide bonds. The POSS-containing PPO networks were microphase-separated. It was found that the POSS cages grafted onto PPO networks were self-organized into the spherical nanodomains. Compared to the control network, the nanocomposites displayed the improved thermomechanical properties and surface hydrophobicity. More importantly, the organic-inorganic networks were self-healable and can be repeatedly processed without sacrificing the mechanical strengths. The exchange reaction of dynamic disulfide bonds is attributable to the self-healing or/and reprocessing properties. In addition, the break and reform of the POSS microdomains are also contributable to the reprocessing behavior at elevated temperature.

Polymer 267, 125648
Tao Zhang
Tao Zhang
Special Research Fellow