19 nm‐Thick Grafted‐To Polymer Brushes onto Optimized Poly(Dopamine)‐Coated Surfaces

Abstract

to carefully consider the interactions of the device's interfaces with the complex media it is subjected to. The type of interactions and their extent can be effectively controlled by modification of the surface using polymer chains. Polymer brush coatings, in particular, can be employed to introduce specific surface properties with great accuracy due to extensive control over variables such as brush thickness, grafting density, polymer architecture, and functional groups. [4][5][6] Polymer brush coatings have therefore been used to equip surfaces with, e.g., antifouling, [7][8][9][10][11][12][13][14] lubricating, [15] and/or (thermo)responsive properties. [16] Polymer brushes are most commonly synthesized by a grafting-from procedure, in which the chains are grown bottom-up from surface-bound initiators. [17,18] This approach is primarily selected because high grafting densities and brush thicknesses can be readily achieved. Additionally, the advent of surface-initiated, controlled polymerization techniques that allow for both the presence of water and oxygen has greatly expanded the potential of grafting-from approaches. [10,[19][20][21][22] However, polymer brushes obtained via surface-initiated polymerization are difficult to characterize, and detailed analysis would optimally involve degrafting of the polymer chains. Degrafting reactions typically require harsh conditions that may damage the polymers and, in addition, large surface areas are needed to obtain sufficient amounts of detached polymer for detailed analysis. [23,24] The primary alternative synthesis route toward polymer brushes is the grafting-to approach. [25] This strategy involves the synthesis of desired polymers in solution followed by their attachment to the target substrate. In contrast with surfacegrown polymers, characterization of solution-grown polymers can be easily performed using straightforward analysis techniques. As a result, valuable information such as polymer molecular weight, polydispersity, and, after immobilization, the grafting density of the polymer brush can be routinely determined. The major disadvantage to the grafting-to strategy is the inherent limitation in attainable layer thicknesses, which generally do not exceed 10 nm. [26] That limitation is at least partially the result of the excluded volume of each polymer chain on the surface, which hinders subsequent, incoming polymers to reach reactive sites on the surface. This thickness limitation might hamper several applications, such as optimal antifouling and self-healing performance, and as such is a highly desirable Grafting-to polymer coatings are typically easy to apply, but the thickness of such coatings is typically limited to a few nanometers, which may hamper applications. This paper presents a grafting-to coating approach that yields polymer brushes up to an unprecedented thickness of 19 nm. To this aim, an easy-to-apply poly(dopamine) (PDA) primer layer is optimized. PDA is an easy-to-apply, but highly complex and chemically not well understood primer layer...

Modular and Substrate-Independent Grafting-To Procedure for Functional Polymer Coatings

“…Poly­(dopamine) deposition was performed by dip-coating of the substrates in a solution of dopamine in NaOAc buffer (pH 7) in the presence of oxidizing agent NaIO 4 . The deposition reaction was performed until approximately 10 nm of poly­(dopamine) could be measured on gold and SiO 2 by spectroscopic ellipsometry (Figure A,B).…”

“…Using the insights developed in the above studies, our group developed an approach to overcome the aforementioned limitations. In previous studies, we have presented a two-step grafting-to procedure that consists of poly­(dopamine) deposition on SiO 2 followed by grafting of poly­(GMA)- b -poly­(NIPAM) block copolymers. , In contrast to the two coating strategies described above, we demonstrated that our procedure could achieve polymer brush coatings of appreciable grafting density, and with thicknesses to 19 nm. In these studies, we demonstrated the grafting of block copolymers of varying sizes and the effect on the resulting thermoresponsive and antifouling properties of the produced poly­(GMA)- b -poly­(NIPAM) brushes .…”

“…In these studies, we demonstrated the grafting of block copolymers of varying sizes and the effect on the resulting thermoresponsive and antifouling properties of the produced poly­(GMA)- b -poly­(NIPAM) brushes . Additionally, we investigated the effect of poly­(dopamine) deposition conditions on subsequent block copolymer grafting and thoroughly investigated chemical and morphological properties (including surface morphology and roughness) of the produced poly­(dopamine) films and poly­(GMA)- b -poly­(NIPAM) polymer brush coatings . Yet, the procedure was exclusively performed on SiO 2 substrates using only poly­(GMA)- b -poly­(NIPAM).…”