Metalorganic frameworks (MOFs), by virtue of their remarkable uptake, capability, selectivity, and ease of regeneration, hold great promise for carbon capture from fossil fuel combustion. However, their stability toward moisture together with the competitive adsorption of water against CO, drastically dampens their capacity and selectivity under real humid flue gas conditions. In this work, an effective strategy was developed to tackle the above obstacles by partitioning the channels of MOFs into confined, hydrophobic compartments by in situ polymerization of aromatic acetylenes. Specifically, polynaphthylene was formed via a radical reaction inside the channels of MOP-S and served as partitions without altering the :underlying structure of the framework. Compared with pristine MOF-5, the resultant material (PN@MOF-5) exhibits a doubled CO, capacity (78 vs 38,cm(3)/g at 273 K and 1 bar), 23 times higher CO2/N-2 selectivity (212 vs 9), and significantly improved moisture stability. The dynamic CO, adsorption capacity can be largely inaintairied (>90%) under humid, conditions during cydes. This strategy can be applied to other MOF materials and may shed light on the design of new MOF polymer materials with tunable pore sizes and environments to promote their practical applications.