Lyophilization‐Free Engineering of Polyelectrolyte Monolith by an Ice‐Dissolving‐Complexation Method

Ice templating is a versatile strategy for structural engineering of hydrophilic polymers and composites, yet the removal of ice templates requires lengthy lyophilization, and the prepared materials need further crosslinking for use in water. This study introduces an ice‐dissolving‐complexation (IDC) method to prepare ice templating monolith in an hour without the need for ice sublimation under a vacuum. The aqueous solution of sodium carboxymethyl cellulose (CMCNa) is frozen, immersed in ethanol/Cu2+ bath (−20 °C). Ice templates dissolved in ethanol, whereby the CMC‐Cu2+ complexation occurred simultaneously to stabilize CMC microstructures. The IDC method enables the preparation and stabilization of CMC monolith with pores and/or aligned channels in one step that is 30–50 times more efficient than lyophilization in terms of the time consumed for ice removal. The IDC method is applicable to various polyelectrolytes and hybrids for straightforward use in water, as exemplified by a proof‐of‐concept CMC‐Cu2+‐carbon nanotubes monolith, which exhibits high performance solar‐steaming under one sun irradiation. An ice‐dissolving‐complexation method is exploited to enable the lyophilization‐free preparation of ice templating monolith in 1 h. The coupling of ice dissolving with complexation facilitates the formation and stabilization of ice templating structures in one step, leading to a task‐specific monolith such as a high performance solar thermal evaporator.