Complexation Controlled Growth Strategy for Preparation of Micrometer-Sized Layered Double Hydroxides for Dual-Functional Gas Barring and Antiphotoaging Applications

Layered double hydroxides (LDHs) have broad applications due to their unique compositions and structures. However, the direct preparation of micrometer-sized functional guest intercalated LDH faces huge challenges. Herein, a complexation controlled growth strategy was proposed for directly preparing micrometer-sized functional guest intercalated LDH. As a proof of concept, micrometer-sized 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP4) intercalated MgZnAl-LDH (BP4-LDH) with high crystallinity was successfully constructed by the strategy that makes the LDH preferentially grow along the <i>ab</i> two-dimensional plane. The composition, structure, and properties of BP4-LDH were systematically characterized by XRD, FT-IR, SEM, TG-DTA, BET, UV-vis, and so on. The introduction of Zn²⁺ into the laminate can significantly increase the crystallinity and size of LDH, and BP4-LDH with an average particle size of 5.87 μm was prepared with a Mg:Zn:Al feeding ratio of 1.5:1.5:1. The addition of BP4-LDH can significantly improve the gas barring and antiphotoaging performance of polyurethane (PU) films. The oxygen transmission rate of PU film was reduced from 1898.0 cm³·cm^-2·day^-1 to 1243.6 cm³·cm^-2·day^-1 by adding 5 wt % 5.87 μm BP4-LDH. Meanwhile, the addition of BP4-LDH effectively lowered the degradation degree of C-H bonds in PU molecular chains under ultraviolet irradiation, and the decreased integral area value of C-H bonds was reduced from 58.1 to 31.3. Therefore, the prepared micrometer-sized BP4-LDH has potential applications in fields of gas barring and antiphotoaging. Meanwhile, the developed complexation controlled growth method can also be used to prepare other micrometer-sized LDH based functional materials.