Unexpected super anti-compressive styrene-acrylonitrile copolymer/polyurea nanocomposite foam with excellent solvent resistance, re-processability and shape memory performance

High-performance, recycling and environmental protection are the goal of the development of polymer materials in the future. The introduction of crosslinking and composite are two main ways to improve the comprehensive properties of materials, however, which leads to the non-recyclability of materials or brings difficulties to the recovery process. Here, we report a polymer nanocomposite foam with superior compression properties to most existing commercial foams, just originating from common commercial styrene-acrylonitrile copolymer (SAN) and polyurea (PUA), and develop a green and energy-efficient method to fabricate high-performance rigid foam by reactive plasticizing and reaction induced phase-separation combining with supercritical CO2 (sc-CO2) foaming. Reaction induced phase-separation results in the in-situ formation of nanoscale structure in the cell walls of the resultant foams, in which the crosslinked PUA is the dispersed phase with the size of 10-40 nm in the matrix of SAN. Optimizing crosslinking network structure of PUA dramatically improve the comprehensive performance of SAN/PUA nanocomposite foams. The resultant SAN/PUA nanocomposite foam shows some performance characteristic of thermosetting polymers, such as excellent heat resistance and solvent resistance than the SAN matrix, meanwhile the performance characteristic of thermoplastic polymers, such as reprocessability. More interestingly, the SAN/PUA nanocomposite foam presents excellent shape memory performance. With the above exceptional performances, this polymer nanocomposite foam will be a perfect substitute for the existing commercial rigid foams.