Key Takeaways & Executive Findings
- •• • Antibacterial efficacy against Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus was evaluated via colony morphology on A16Se+xPDMS versus pristine PDMS (Figure 6A), with SEM confirming adhesion differences after 3 h of interaction (Figure 6B); this matters because Pseudomonas is a dominant marine biofilm former and its inclusion addresses the reviewer's demand for relevant fouling targets. • • Chlorella adhesion was quantified by fluorescence microscopy and fluorescence intensity (Figure 6C, 6D), providing a direct microalgal fouling metric; reduced intensity on A16Se+xPDMS indicates lower biomass retention, which is industrially significant because microalgal slimes initiate the conditioning layer that precedes macrofouling. • • Zeta potential measurements (Figure 6E) characterize surface charge for pristine PDMS and the A16Se+xPDMS series; charge modulation is mechanistically linked to reduced electrostatic attraction of fouling organisms, a parameter that can be tuned without altering bulk mechanical properties. • • Seawater immersion panels were imaged after 3 months (Figure 6F), demonstrating field-relevant durability; this duration exceeds typical accelerated laboratory assays and provides evidence that the selenonium-catalyzed network does not degrade catastrophically under saline exposure, a prerequisite for any antifouling coating.
Abstract
Marine biofouling imposes substantial operational penalties on maritime assets, yet commercial silicone foul-release coatings rely on static, non-adaptive networks that cannot be reprocessed or repaired. This work introduces selenonium-salt-catalyzed dynamic siloxane exchange as a route to polydimethylsiloxane (PDMS) vitrimer coatings. The authors incorporate A16Se+ organoselenium catalysts into PDMS networks at loadings designated A16Se+xPDMS, enabling thermally activated siloxane bond exchange that confers vitrimeric stress relaxation, reprocessability, and high-temperature self-healing. Antibiofouling performance is benchmarked against pristine PDMS using colony morphology assays for Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, SEM imaging of bacterial adhesion after 3 h, Chlorella fluorescence adhesion quantification, zeta potential measurements, and 3-month seawater immersion panels. Reviewer 1 questioned the direct relevance of recyclability and high-temperature self-healing to marine antifouling and requested that surface elastic modulus and Pseudomonas antibacterial data be elevated to the main text. In response, the authors relocated scratch and self-healing results from Figure 5 to Supporting Information Figures S12 and S13, condensed the main-text discussion, and integrated surface elastic modulus data into Figure 4G and Pseudomonas antibacterial results into Figure 6A. The revised manuscript positions dynamic exchange as supporting evidence of network dynamics rather than as a primary antifouling metric, while foregrounding modulus and antibacterial performance as the application-relevant properties.
1. Introduction
Commercial silicone foul-release coatings based on pristine PDMS rely on low surface energy and elastic modulus to weaken bioadhesive attachment. These static networks cannot be reprocessed, repaired, or reverted after mechanical damage, and they offer no intrinsic antibacterial activity. The resulting operational friction is twofold: damaged coatings require full removal and reapplication, and biofilm formation on compromised surfaces negates the foul-release mechanism. Existing vitrimer chemistries—transesterification, disulfide exchange, imine metathesis—often require high catalyst loadings, suffer from moisture sensitivity, or introduce hydrophilic moieties that degrade antifouling performance.
This study deploys selenonium salts as dynamic siloxane exchange catalysts within a PDMS matrix, creating a vitrimeric network that retains silicone surface characteristics while enabling thermally triggered bond rearrangement. The experimental protocol systematically varies A16Se+ loading (A16Se+xPDMS) and benchmarks antibacterial activity against three bacterial strains, microalgal adhesion via Chlorella fluorescence, surface charge via zeta potential, and 3-month seawater immersion performance. By relocating self-healing and scratch data to Supporting Information and elevating surface elastic modulus (Figure 4G) and Pseudomonas antibacterial results (Figure 6A) to the main text, the revised manuscript aligns the evidentiary focus with marine antifouling requirements rather than reprocessability metrics.
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CHEN Hong, AN Xiaowei, CHEN Sisi, XU Yiming, HE Hanliang, WEI Chunyang, LI Jiajia, ZHANG Wei, ZHANG Zhengbiao, ZHU Jian, PAN Xiangqiang (2026). Selenonium-Catalyzed Dynamic Siloxane Exchange for PDMS-Vitrimer Coatings. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-026-4248-2
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Frequently Asked Questions
What is the failure mechanism of the selenonium-catalyzed siloxane exchange under prolonged seawater exposure, and how was it assessed?
The 3-month seawater immersion test (Figure 6F) provides the primary durability assessment. Panels were imaged before and after immersion, and the absence of catastrophic delamination or bulk erosion indicates that the selenonium catalyst remains active within the hydrophobic PDMS matrix without leaching or hydrolyzing. The dynamic exchange is thermally activated; at ambient seawater temperatures, exchange rates are negligible, preserving network integrity. Failure would manifest as surface cracking, modulus drift, or loss of antibacterial activity, none of which were reported over the 3-month window.
How does the antibacterial performance against Pseudomonas aeruginosa compare to pristine PDMS, and what is the proposed mechanism?
Figure 6A presents colony morphology for Pseudomonas aeruginosa on pristine PDMS and the A16Se+xPDMS series. The selenonium-functionalized surfaces reduce colony formation relative to pristine PDMS. The mechanism is attributed to the cationic selenonium moieties disrupting bacterial membrane integrity, combined with the low-surface-energy PDMS matrix that weakens adhesion. SEM images after 3 h (Figure 6B) show altered bacterial morphology on A16Se+10PDMS versus PDMS, consistent with membrane disruption rather than simple anti-adhesion.
What is the surface elastic modulus of the A16Se+xPDMS coatings, and why was it moved to the main text?
Surface elastic modulus data are now presented in Figure 4G. Reviewer 1 specifically requested this parameter because modulus governs foul-release behavior: lower modulus reduces the shear stress required for biofouling detachment. The modulus values for the A16Se+xPDMS series are reported alongside pristine PDMS, demonstrating that selenonium incorporation does not compromise the low-modulus characteristic essential for silicone foul-release coatings. This placement in the main text reflects its direct relevance to antifouling performance.
Does the vitrimeric dynamic exchange compromise the coating's mechanical integrity or antifouling function under service conditions?
The dynamic exchange is thermally gated. At service temperatures (ambient marine conditions), exchange rates are sufficiently slow that the network behaves as a conventional crosslinked PDMS. Stress relaxation and reprocessing occur only at elevated temperatures, as documented in the Supporting Information (Figures S12 and S13). The 3-month seawater immersion results (Figure 6F) and the retained antibacterial activity (Figure 6A) confirm that the vitrimeric character does not degrade antifouling performance under field-relevant conditions.
What is the scalability and cost profile of selenonium-catalyzed PDMS vitrimer coatings compared to established silicone foul-release technologies?
The manuscript does not provide explicit cost analysis. Selenonium salts are specialty chemicals, and their loading (A16Se+xPDMS series) influences cost. The synthesis route is solution-based and compatible with existing PDMS coating application methods. The primary scalability bottleneck is the availability and cost of the A16Se+ catalyst at industrial scale. The 3-month seawater panel test (Figure 6F) demonstrates field viability, but a full techno-economic assessment against commercial silicone foul-release coatings remains outside the scope of this study.
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