Application Of Polyamidoamine Dendrimer Using For Supercritical CO₂Foaming Of Polymer

Polyamidoamine （PAMAM） dendrimer is a perfect tree structuremacromolecules with highly branched, loose structure and controlledsurface functionality, which provide a number of potential applications. Inthis paper, the PAMAM, as a dendrimer with strong absorption of CO₂, wasintroduced into the polymer supercritical CO₂foaming to increase CO₂solubility and improve the cell structure. The research contents were asfollows:（1）3.0G PAMAM dendrimer was prepared for blending withPolystyrene （PS） and Polypropylene （PP）, then the composites were used forsupercritical CO₂foaming. The processability, dynamic mechanicalproperties of the composites and the cell structure of the foams were studied.The results showed that with the increased content of PAMAM, the celldensity and cell size of PS/PAMAM foams were gradually increased anddecreased respectively. Compared to non-foaming pure PP, PP/PAMAMimproved its cell structure.（2） Two different length of multi-wall carbon nanotubes （MWCNTs）were grafted with3.0G PAMAM, and then PS chain was introduced by atomtransfer radical polymerization （ATRP）, which was used in PS matrix as a nucleating agent for supercritical CO₂foaming. We investigated the surfacegrafting of modified MWCNTs, the dispersion in PS matrix, the dynamicmechanical properties of the composites and the cell structure of the foams.The results showed that the addition of modified MWCNTs significantlyreduced the cell size and increased the cell concentration.（3） The surface of SiO₂nano-particles was grafted with3.0G PAMAM,then PS chain was introduced by ATRP method. Then modified SiO₂wasused as a nucleating agent in PS matrix for supercritical CO₂foaming. Thesurface grafting of modified SiO₂, the dispersion in PS matrix, and the cellstructure of the composites foams were investigated. The results showed theaddition of modified SiO₂significantly reduced the cell size and increasedthe cell concentration.