Thermally responsive polyrotaxanes synthesized through the telomerization of N-lsopropylacrylamide with polypseudorotaxanes made from α-cyclodextrin threaded onto thiolated poly(ethylene glycol)

The synthesis of thermally responsive polyrotaxanes through the telomerization of N-Isopropylacrylamide (NIPAAm) with polypseudorotaxanes, which is made from α-cyclodextrin (CD) threaded onto thiolated polyethylene glycol (PEG), was analyzed. NIPAAm was purified by recrystallization from n-hexane, α-CD and acetophenone were used as received. A saturated aqueous solution containing a predetermined amount of α-CD was added to certain volume of a 20 wt % PEG-thiolated macromer solution in water at room temperature. After centrifugation and filtration, the filtrate was collected and dialyzed for 7 days in deionized water in dialysis tubing and finally the dialyzed solution was freeze-dried to five the power product. The results shows that optical transmittance and DSC measurements resulted polyrotaxanes possessed an interesting LCST around 38°C, close to the temperature of human body.