Wide Range of Functionalized Poly(N-alkyl acrylamide)-Based Amphiphilic Polymer Conetworks via Active Ester Precursors

A versatile strategy for the fabrication of functional and nanostructured poly(N-alkyl acrylamide)-based amphiphilic polymer conetworks (APCNs) from hydrophobic precursor networks is presented. The active ester monomer pentafluorophenyl acrylate (PFPA) fulfills a dual role: it provides miscibility with hydrophobic macromonomer cross-linkers and activates the acrylate for amidation reactions. Thereby, it acts as a general hydrophobic masking group for N-alkyl acrylamides, and enables the transformation of PFPA-based hydrophobic precursor networks into a multitude of different poly(N-alkyl acrylamide)-l-PDMS APCNs. These optically transparent APCNs possess nanophase-separated morphologies with domain sizes in the nanometer range. Variation of the amide results in different types of APCNs, despite them being derived from the same precursor network and having identical network structures. Accordingly, the properties of these APCNs can be tailored to the desired application by simple variation of the amide functionality. Furthermore, the combination of PFPA with another hydrophobically masked monomer allows for the fabrication of APCNs with small yet precisely defined amounts of functional amide units in the hydrophilic phase. A controlled functionalization of APCNs with pendant groups such as pH-responsive imidazole, fluorescent dyes, and biotin for specific protein binding is achieved, greatly expanding the functionality of the APCNs. Such functionalized APCNs could find application as stimuli-responsive drug delivery membranes, smart hydrogels, biosensors, or matrices for biocatalysis.