Recent Advances in De Novo Synthesis of Interfacial Two-Dimensional Polymers

Two-dimensional polymers (2DPs) integrate the molecular programmability of synthetic polymers with the reduced dimensionality and surface accessibility of atomically thin materials. Realizing their functional potential and establishing reliable structure–property relationships, however, require precise control over lattice topology, crystallinity, orientation, thickness, and defect structure. Interfacial polymerization is particularly suited to this objective because interfaces confine network formation while regulating molecular organization, reactant transport, bond-formation kinetics, nucleation, crystal growth, and defect evolution. This Review summarizes the molecular design principles underlying interfacial 2DP synthesis and compares four major environments according to whether polymerization occurs at a liquid or solid surface: air–liquid, liquid–liquid, solid–liquid, and vapor–solid interfaces. We contrast liquid surfaces, which couple dynamic confinement with transport-regulated molecular reorganization and scalable film growth, with solid surfaces, which provide adsorption, templating, and catalytic control while enabling direct mechanistic investigation at the molecular scale. We further examine how precursor organization, mass transport, crystallization pathways, stacking, and defect evolution collectively determine the structural quality of 2DPs. Particular attention is given to mechanistic insights from advanced characterization methods that directly track nucleation and domain-growth dynamics and resolve grain-boundary and defect structures from molecular to atomic resolution. Emerging electronic and stimuli-responsive devices are discussed to illustrate how framework design, structural quality, and interfacial organization translate into functional performance. Finally, we identify opportunities to advance interfacial polymerization from empirical optimization toward predictive synthesis that bridges local atomic precision with macroscopic structural uniformity.