Synthesis and characterization of a poly(N‐isopropylacrylamide) with β‐cyclodextrin as pendant groups

A novel linear poly(N‐isopropylacrylamide) (PNIPA) with β‐cylodextrin (β‐CD) moiety (PNIPA‐β‐CD) was synthesized by the conjugation of β‐CD carrying amino groups (EDA‐β‐CD) onto PNIPA with epoxy groups (P(NIPA‐co‐GMA), Mn = 3.86 × 104), and the related reaction conditions are investigated. PNIPA‐β‐CD was characterized by means of IR, NMR and UV spectroscopes, element analysis, and differential scanning calorimetry (DSC). The number‐average molecular weight (Mn) and the β‐CD content of the obtained PNIPA‐β‐CD are 4.87 × 104 and 18.8 wt %, respectively. PNIPA‐β‐CD can not only respond to temperature stimuli but also include guest molecules. Lower critical solution temperature (LCST) of aqueous PNIPA‐β‐CD solution is similar to that of PNIPA. The association constant (Ka) for PNIPA‐β‐CD with methyl orange (MO) is 2.4 × 103 L mol−1 at pH 1.4, which is comparable to that of EDA‐β‐CD (Ka = 2.9 × 103 L mol−1).