Carbon dioxide is a clean and versatile solvent for the synthesis and proce
ssing of a range of materials. This review focuses on recent advances in po
lymer synthesis and processing using liquid and supercritical CO2. The synt
hetic techniques discussed include homogeneous solution polymerisation, pre
cipitation polymerisation, dispersion and emulsion polymerisation, and bulk
polycondensation. The formation of porous polymers and polymer blends is a
lso considered, and the specific advantages of CO2 in these processes are e
valuated in each case. The use of CO2 as a solvent for polymer processing i
s reviewed from a materials perspective, with particular attention being gi
ven to the formation of polymers with well defined morphologies. The variab
le solvent strength associated with supercritical fluids has been utilised
in areas such as polymer fractionation and polymer extraction. Plasticisati
on phenomena have been exploited for the impregnation and heterogeneous che
mical modification of polymeric materials. The formation of microcellular p
olymer foams by pressure induced phase separation is considered, as is the
use of CO2 for polymer particle formation, spray coating, and microlithogra
phy. The aim of the review is to highlight the wide range of opportunities
available to the materials chemist through the use of carbon dioxide as an
alternative solvent.