Complex amphiphilic networks derived from diamine-terminated poly(ethylene glycol) and benzylic chloride-functionalized hyperbranched fluoropolymers

Amphiphilic copolymer networks were prepared from hyperbranched fluoropolymer (HBFP*, M _n = 38 kDa, by atom transfer radical-self condensing vinyl copolymerization) and linear diamine-terminated poly(ethylene glycol) (DA-PEG, M _n = 1,630 Da). Model studies found that the crosslinking mechanism occurred at ambient temperature as a result of reaction between DA-PEG and the benzylic chlorides of HBFP*. These networks underwent covalent attachment to glass microscope slides derivatized with 3-aminopropyltriethoxysilane, whereupon gel percent studies at various weight percentages of DA-PEG to HBFP* found that curing could be achieved at lower temperatures and shortened time periods relative to the previously reported parent HBFP-PEG system. Thermogravimetric analysis revealed that the crosslinked materials gave no evident mass loss up to 250 °C. Differential scanning calorimetry of the complex amphiphilic networks showed a suppressed glass transition temperature, relative to that observed for neat HBFP*, and multiple melting DA-PEG endotherm(s) near 30 °C. The films possessed a topographically-complex surface with features that increased in tandem with an increase in the ratio of DA-PEG to HBFP*, as detected by atomic force microscopy and quantified by increased rms roughness values. Internal reflection infrared imaging revealed a heterogeneous surface composition and confirmed that the domain sizes increased as the weight percent of DA-PEG increased.