Symmetry-Guided Benzene Additives for Ultrafast and Selective Polydopamine Deposition

Polydopamine (pDA), formed by oxidative self-polymerization of dopamine, is a versatile coating platform, yet conventional aqueous routes typically produce thin films at slow rates. In this study, we introduce a symmetry-guided, mechanism-based additive strategy that transforms this canonical system. Pairing benzene-1,2,4,5-tetraol (Ph-sym-(OH)₄) with Tris buffer and benzene-1,2,4,5-tetracarboxylic acid (Ph-sym-(COOH)₄) with NaIO₄ affords thickness enhancements of ∼5-50× at 10 mol % additive loading and exceptionally large thickness enhancements at higher tetraacid loadings (mol %), without specialized equipment, whereas all cross-pairings fail. Tetraol-assisted pDA coatings yielded superhydrophilic surfaces (water contact angle <10°), while tetraacid-assisted pDA coatings produced moderately hydrophilic surfaces (water contact angle of 30-40°). Positional scanning identified the 1,2,4,5-symmetric geometry as uniquely effective, enabling multivalent, predominantly noncovalent interactions─hydrogen bonding, acid-base pairing, and π-π stacking─between early pDA oligomers and the additive. Control experiments confirm that the additives do not form coatings independently but instead mediate dopamine polymerization. Infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy corroborated this additive-induced network assembly, revealing continuous overlayers and pronounced surface roughening. This condition-additive matching principle provides a practical, plug-and-play route to ultrafast and selective pDA deposition, offering a broadly applicable design concept for catechol-derived coatings.