Melamine

Melamine foam (MF) is ultra-lightweight, open-cell, fire-retardant, with excellent sound/thermal insulation and oil absorption properties. However, the triazine-based backbone of MF is inflexible, leading to brittleness. Approaches to toughen MF: (i) physical blending of nanoparticles, flexible polymers/fibers into melamine-formaldehyde (MF) resin, (ii) end-capping of amino groups to reduce cross-link density, (iii) incorporation of flexible spacers (e.g. PVA, allyl glycidyl ether).
Synergistic formulations can enhance elongation while maintaining flame retardance. Pore structure is also important. For example, microwave foaming creates high-aspect-ratio ligaments that deform under compression, with 17 times higher compressive strength than oven-foamed, plate-like struts. Ideal viscosity and well-balanced foaming/curing agents lead to monodisperse, low-density cells. Carbonized MF can form ultralight carbon foams/aerogels with tuneable pores, low thermal conductivity, and strong microwave absorption, leading to potential for aerospace thermal insulation and EMI shielding.

Fig. 1 Production process of Melamine foams. (Wang Y.; et al. 2023)

N-doped porous carbons were prepared by carbonizing commercial melamine-formaldehyde resin and subsequent KOH activation at different temperatures and KOH loadings. Narrow micropores (< 1 nm) govern ambient-pressure uptake, while high N-levels enhance selectivity. The sorbents show fast kinetics, moderate adsorption heat, excellent CO2/N2 selectivity, stable cyclic performance and good dynamic capacity under flue-gas conditions, demonstrating that low-cost melamine-formaldehyde resin is an outstanding precursor for efficient CO2 capture adsorbents.

Fig. 2 Melamine-formaldehyde resin for synthesizing highly porous carbon materials. (Tian L.; et al. 2024)