A New Approach for the Synthesis of pH‐Responsive Cross‐Linked Micelles from a Poly(glycidyl methacrylate)‐Based Functional Copolymer

Abstract

An amphiphilic poly(ethylene glycol)methyl ether‐block‐poly(glycidyl methacrylate) (MPEG‐b‐PGMA) diblock copolymer is first synthesized via atom transfer radical polymerization. Epoxy groups of this precursor block copolymer are converted to hydroxyl and tertiary amine residues by reacting with diethyl amine over a ring‐opening reaction. The resulting diblock copolymer is poly(ethylene glycol)methyl ether‐block‐poly(3‐diethylamino‐2‐hydroxypropyl methacrylate) (MPEG‐b‐PDEAHPMA). Micellar solution of this diblock copolymer is prepared at pH 12.0 in aqueous media. At high pH (12.0), core– shell micelles are formed with PDEAHPMA‐core and MPEG‐shell. PDEAHPMA blocks have both hydroxyl and tertiary amine groups that provide reactivity against divinyl sulfone (DVS) and a response to solution pH, respectively. Cross‐linking of hydroxyl groups of PDEAHPMA chains in the micelle core is successfully achieved by adding DVS. At pH 2.0, the DEAHPMA‐core of core cross‐linked (CCL) micelles becomes protonated and hence swelling is observed. The effect of varying the DVS concentrations is also studied. The micelle formation of diblock copolymer and its response to solution pH are investigated by using surface tensiometer, 1H NMR spectroscopy, and dynamic light scattering (DLS) techniques. CCL micellar structure and its response to solution conditions are investigated with transmission electron microscopy and DLS studies, respectively. image