Highly Oil-Repellent Thermoplastic Boundaries via Surface Delivery of CF₃ Groups by Molecular Bottlebrush Additives

Abstract

We fabricated thermoplastic surfaces possessing extremely limited water and oil wettability without employment of long-chain perfluoroalkyl (LCPFA) substances. Namely, by taking advantage of the structure and behavior of original oleophobic perfluoropolyether (PFPE) methacrylate (PFM) molecular bottlebrush (MBB) additive we obtained polymeric surfaces with oil contact angles well above 80° and surface energy on the level of 10 mN/m. Those angles and surface energies are the highest and the lowest respective values reported to date for any bulk solid flat organic surface not containing LCPFA. We show experimentally and computationally that this remarkable oil repellency is attributed to migration of small quantities of the oleophobic MBB additives to the surface of the thermoplastics. Severe mismatch in the affinity between the densely grafted long side chains of MBB and a host matrix promotes stretching and densification of mobile side chains delivering the lowest surface energy functionalities (CF3) to the materials’ boundary. Our studies demonstrate that PFM can be utilized as an effective low surface energy additive to conventional thermoplastic polymers, such as poly­(methyl methacrylate) and Nylon-6. We show that films containing PFM achieve the level of oil repellency significantly higher than that of polytetrafluoroethylene (PTFE), a fully perfluorinated thermoplastic. The surface energy of the films is also significantly lower than that of PTFE, even at low concentrations of PFM additives.

Design, synthesis, and evaluation of a highly effective and safe perfluoro-alternative with a “weak site”: potassium 1,1,2,2,3,3,4,4-octafluoro-4-(perfluorobutoxy)butane-1-sulfonate

“…[6][7][8][9][10][11][12][13][14][15][16][17] It is difficult to modify the structure of perfluorinated compounds, which are mainly modified by perfluorinated derivatives in a late stage. 18 Besides, more by-products are obtained through the conventional fluorination reaction. 19 It also takes time and is economically costly from detection to environmental and health assessments, as well as due to technical secrecy and other considerations, 14,20,21 so research regarding the development of relatively efficient and safe perfluorinated substitutes is progressing slowly.…”

Towards a Long-Chain Perfluoroalkyl Replacement: Water and Oil Repellent Perfluoropolyether-Based Polyurethane Oligomers

“…The difference could be connected to the surface energy of the repeating units constituting macromolecular chains. To this end, we estimated surface energies and their (polar and dispersive) components (SI: S6) for the molecular segments constituting FOPUs using algorithms reported elsewhere [20,36]. The calculated values are presented in SI, Table S4.…”

“…The surface energy values estimated from the contact angle of hexadecane are close, but to some extent different from the ones obtained by the Owens-Wendt method utilizing both WCA and HDCA. We associate this difference with the differences in the size of the wetting liquids, which plays a significant role in the wettability of polymer surfaces [20,21,36]. Based on molecular weight and chemical structure, the size of water molecule is about an order of magnitude smaller than that of hexadecane.…”

“…To this end, perfluoropolyether derived (co)polymers and cross-linked materials have been shown in our previous works and that of others to have the ability to serve as hydrophobic/lyophobic materials and interfaces [20][21][22][23][25][26][27][28][29][30][31][32][33][34][35][36][37]. In particular, we have found that when PFPE-based triblock polyesters [20,21,37] or methacrylic molecular brushes [36] are added to engineering thermoplastic (PET, nylon 6, or polymethyl methacrylate) films, they readily migrate to the film surface, imparting significant water and oil repellency to the thermoplastic boundary. Specifically, the macromolecular additives populated the boundary with PFPE segments terminated with C 4 F 9 -perfluoroalkyl moiety, which cannot yield unsafe long-chain perfluoroalkyl carboxylic acids.…”

Mesoscale Modeling of Agglomeration of Molecular Bottlebrushes: Focus on Conformations and Clustering Criteria

“…In our recent study [42], oleophobic perfluoropolyether (PFPE) methacrylate molecular bottlebrush (PFM) was synthesized and used as an additive to commodity thermoplastics (nylon 6 and poly(methyl methacrylate)). Our studies showed that an addition of only 1% to 5% of the PFM bottlebrush additives imparts high water and oil repellency to the host thermoplastic matrix.…”