Amphiphilic and hydrophobic surface patterns generated from hyperbranched fluoropolymer/linear polymer networks: Minimally adhesive coatings via the crosslinking of hyperbranched fluoropolymers

Abstract

Hyperbranched fluoropolymers (HBFPs), based on benzyl ether linkages and having a large number of pentafluorophenyl chain ends, were crosslinked by a reaction with diamino‐terminated poly(ethylene glycol) (PEG) or diamino‐terminated poly(dimethyl siloxane) (PDMS) to form hyperbranched–linear copolymer networks of different compositions, structures, and properties. The crosslinking reactions involved the nucleophilic aromatic substitution of the pentafluorophenyl para‐fluorines of HBFP by the amine functionalities of the respective telechelic linear segments. The contact angles, differential scanning calorimetry, thermogravimetric analysis, tensile measurements, and atomic force microscopy (AFM) were used to characterize the resulting network film samples. The surface wettability of the crosslinked materials was affected by the nature and amount of the linear polymer crosslinking agent employed. Amphiphilic polymer networks were formed by the incorporation of diamino‐terminated PEG as a crosslinker, whereas diamino‐terminated PDMS produced polymer networks of a hydrophobic character. The mechanical properties improved upon crosslinking, as measured by tensile testing. The mechanical integrity of the films was also found to improve upon crosslinking, as measured by AFM machining protocols. The AFM images revealed topographical morphologies that appeared to be the result of phase segregation of HBFP from PEG or PDMS; the dimensions of the phase‐segregated domains were dependent on the stoichiometry of HBFP to the linear polymer and the thickness of the coating. As the content of PEG increased, fouling by human fibrinogen, used as a model protein, decreased. Further studies are in progress to determine the effects of the surface composition, morphology, and topography on the biofouling characteristics. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3531–3540, 2003

Hyperbranched Fluoropolymers and their Hybridization into Complex Amphiphilic Crosslinked Copolymer Networks

“…[41] Crosslinking was afforded by the nucleophilic aromatic substitution of the para-fluorines of the pentafluorophenyl groups present in HBFP (I) by the amino termini of the PEG chains using a stoichiometric amount of diisopropylethyl amine (DIEA) in THF at a reflux for 20 h [Scheme 4(a)]. Moreover, Scheme 4 illustrates that in addition to the bifunctionality of the DA/PEG chains establishing bridging crosslinks between the hyperbranched macromolecules, monoattachment was possible, leaving a free amine endgroup, remaining after the reaction of only one of the two amino termini of the linear polymer chain.…”

“…The content of this feature article will build from these amphiphilic types of materials, with emphasis upon the production of amphiphilic crosslinked networks that combine all desired features of compositional and structural heterogeneity, being composed of HBFPs and linear PEG. [41][42][43] These materials were developed initially as non-toxic, anti-biofouling coatings for application in the marine environment, and they have demonstrated remarkable perormance toward this application. [44] Moreover, their complex morphologies were also found to provide nanochannels that exhibit unusual thermallypromoted release of volatile guest molecules, [45] and nanoscale confinement of water swollen within the materials to result in dramatically increased moduli.…”

“…It was also verified that HBFP (I) could be further functionalized via nucleophilic aromatic substitution through its pentafluorophenyl groups. [16,41] HBFP (I) exhibited a glass transition temperature (T g ) of 54 8C, as measured by DSC, and excellent thermal stability with no mass loss up to 300 8C, as determined by thermogravimetric analysis (TGA). Noteworthy, HBFPs were also prepared by the polycondensation of an A 4 B monomer 3,5-bis[3 0 ,5 0 -bis-(pentafluorobenzyloxy)benzyloxy]benzyl alcohol.…”

Temperature‐dependent phase‐segregation behavior and antifouling performance of UV‐curable methacrylated PDMS/PEG coatings

“…12 Research has demonstrated that two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic polymer surfaces. 12 Pioneer research in such binary systems comes from the work of Wooley and coworkers, [13][14][15] who reported amphiphilic polymer coatings prepared by the in situ phase separation and crosslinking of hyperbranched fluoropolymers and linear PEG networks for efficient antifouling coatings. Since then, surface-active block copolymers with fluoroalkyl side chains, amphiphilic semifluorinated block copolymers have been explored in antifouling coatings.…”

Formation of surface-grafted polymeric amphiphilic coatings comprising ethylene glycol and fluorinated groups and their response to protein adsorption

“…For instance, Wooley and co-workers synthesized a series of polymeric networks comprising hyperbranched fluoropolymers and poly͑EG͒ chains and studied their resistance against a variety of proteins and zoospores of green fouling alga. [9][10][11] The group reported that the coating's performance depended on the chemical composition and the topographical heterogeneity of the surface. In another strategy, Krishnan et al used amphiphilic diblock copolymers comprising EG and fluorinate blocks.…”