Functional polymer films offer a versatile platform for tailoring surface properties for various applications. Particularly, polymers incorporating both polar and nonpolar groups have emerged as alternatives for designing responsive coatings due to their natural tendency to rearrange their interface to minimize their interfacial free energy with diverse media.
1 While atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization have been extensively employed for crafting responsive polymer coatings, ring-opening metathesis polymerization (ROMP) has been relatively overlooked despite its advantages in rapid polymerization rates, high monomer conversion, and narrow molecular weight distribution.
2–4 The limited functional group tolerance and availability of functionalized ROMP monomers comprise some of the main restrictions for this limited attention.
5 Thus, there is a need for a methodology to fabricate responsive polymer films via ROMP to expand its applicability. In this work, we have fabricated solvent-responsive polymer-based thin films using a norbornene diacyl chloride (NBDAC) monomer that can be readily functionalized with amine-containing functional molecules bearing an amphiphilic composition to impart our desired functionality. These polymeric films have been synthesized by combining a spin-coating deposition technique with surface-initiated ROMP, which represents an adaptation of a methodology recently developed in our group.
6 This combination of methods and techniques has enabled uniform, reproducible, and fast fabrication of polymer thin films that can be quickly modified and characterized. Since each polynorbornene repeating unit in this polymer contains the amphiphilic functionality, this film presents a high density of functional groups, enhancing its interfacial responsiveness. The morphology and chemical composition of the resulting films have been evaluated using SEM, FTIR spectroscopy, and contact angle measurements. Wettability data was also utilized to determine the solvent-responsive properties of these films using a surface energy calculation approach that we have developed to quantify the surface rearrangement that occurs upon contact with media of varying polarity. With this study, we introduce a synthesis approach for designing and investigating responsive surfaces with a tailored film composition.
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(4) Bielawski, C. W.; Grubbs, R. H. Living Ring-Opening Metathesis Polymerization. Progress in Polymer Science 2007, 32 (1), 1–29. https://doi.org/10.1016/j.progpolymsci.2006.08.006.
(5) Leitgeb, A.; Wappel, J.; Slugovc, C. The ROMP Toolbox Upgraded. Polymer 2010, 51 (14), 2927–2946. https://doi.org/10.1016/j.polymer.2010.05.002.
(6) Parkerson, Z. J.; Prozorovska, L.; Vasuta, M. P.; Oddo, T. D.; Jennings, G. K. Simultaneous Spin Coating and Ring-Opening Metathesis Polymerization for the Rapid Synthesis of Polymer Films. ACS Appl. Mater. Interfaces 2024, 16 (13), 16754–16766. https://doi.org/10.1021/acsami.4c00211.
