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

Abstract

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) acts as a general hydrophobic masking group for N-alkyl acrylamides, by providing both miscibility with hydrophobic macromonomer crosslinkers and activating the acrylate for amidation reactions. Thereby, hydrophobic precursor networks can be transformed into a multitude of different poly(N-alkyl acrylamide)-l-PDMS APCNs. The resulting optically transparent APCNs possess nanophase-separated morphologies with domains sizes in the nanometer range. Variation of the amide type 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 according 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 as matrices for biocatalysis.

Self‐Healing Metallo‐Supramolecular Amphiphilic Polymer Conetworks

“…They correspond to the PDMS and active ester phases, respectively (Figure S6, Supporting Information). This confirms the presence of phase‐separated morphologies as previously reported . 4‐Aminopyridine was reacted with the active ester‐based precursor in THF at 60 °C to yield poly( N ‐(pyridin‐4‐yl)acrylamide)‐ l ‐polydimethylsiloxane (PNP4A‐ l ‐PDMS) APCNs.…”

“…They are then converted into amphiphilic materials by cleavage of the masking group, leading to phase‐separated nanostructured polymer networks. Recently, pentafluorophenyl acrylate (PFPA) has been reported as a suitable hydrophobically masked monomer that simultaneously is in active ester and therefore allows to prepare a wide range of functionalized poly(acrylamide)‐based APCNs . Thus, we used poly(pentafluorophenylacrylate)‐ l ‐polydimethylsiloxane (PPFPA‐ l ‐PDMS) precursor conetworks to prepare functionalized APCNs.…”

“…The PPFPA‐ l ‐PDMS conetwork precursors were synthesized by UV‐initiated polymerization in the presence of Irgacure 651 (2,2‐dimethoxy‐1,2‐diphenylethan‐1‐one) according to the previously described procedure . A monomer mixture containing 50 wt% of PFPA and 50 wt% of PDMS was prepared and further diluted with 10 wt% of THF into which the initiator had been dissolved ( Figure ).…”

Pyranine‐Modified Amphiphilic Polymer Conetworks as Fluorescent Ratiometric pH Sensors

“…The ability to selectively load either or both phases with hydrophilic or hydrophobic compounds, respectively, for example drugs or sensing entities, offers access to even more complex functional materials. Recently, we have presented a new method for the fabrication of active ester‐based APCNs that can be covalently functionalized in a controlled and convenient manner with a large variety of different entities …”

“…It was monitored by attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR, Figure b; Figures S1 and S2, Supporting Information) as well as fluorescence and UV–vis spectroscopy (Figure c; Figure S3, Supporting Information). First, a homogeneous hydrophobic precursor membrane (preAPCN) was synthesized via photopolymerization of TMS‐protected 2‐hydroxyethyl acrylate (TMS‐HEA) and the hydrophobic reactive ester monomer pentafluorophenyl acrylate (PFPA) together with a PDMS macromonomer crosslinker (MA‐PDMS‐MA) (FTIR spectra of all components in Figure S1, Supporting Information). The weight ratio of HEA to PDMS was 3:2 to allow for good swelling ability in water.…”