Property changes of powdery polyacrylonitrile synthesized by aqueous suspension polymerization during heat-treatment process under air atmosphere

Polyacrylonitrile Nanoparticle‐Derived Hierarchical Structure for CO2 Capture

“…[45] Therefore, the first drop in mass (curve "PAN air") starting at 250-260 8C, corresponds to the release of gaseous products (such as NH 3 , HCN,a nd H 2 O). [28,29] We observedt he melting of the PA N nanoparticles that were produced in air between 260 and 270 8C. This value is lower than the reported range,i .e., 317-369 8C, but is highly dependent on the heating rate and molecular weight.…”

“…Moreover, PAN is known to degrade before reaching its melting point, most probably due to the formation of the ladder structure . Therefore, the first drop in mass (curve “PAN air”) starting at 250–260 °C, corresponds to the release of gaseous products (such as NH 3 , HCN, and H 2 O) . We observed the melting of the PAN nanoparticles that were produced in air between 260 and 270 °C.…”

“…Polyacrylonitrile, a well‐known precursor for the synthesis of carbon fibers, can be thermally modified to form a very resistant structure (graphite‐like) that still comprises beneficial nitrogen. This thermal resistance is the result of cyclization reactions that occur between two neighboring cyanide functional groups and dehydrogenation of the polymer backbone . Moreover, the ternary‐coordinated nitrogen in the cyanide group permits some extent of chemisorption due to its partial basicity, without the necessity for high heat of regeneration, as it is required for amines .…”

“…[19][20][21] While materials such as glucose,aromatic polymers, or activated carbonsr equire functionalization using amines [19,[22][23][24] or ammonia [20] to be effective enough,s everal polymers such as polyaniline, [25] polyacrylonitrile, [21,22] and polypyrrol [26] have been successfully used as nitrogen-containing base materialsw ithout additional functionalization. Polyacrylonitrile,aw ell-known precursorf or the synthesis of carbon fibers, [27,28] can be thermally modifiedt of orm av ery resistant structure (graphite-like) that still comprises beneficial nitrogen. This thermal resistance is the result of cyclization reactions that occur between two neighboring cyanide functional groups and dehydrogenation of the polymer backbone.…”

“…This thermal resistance is the result of cyclization reactions that occur between two neighboring cyanide functional groups and dehydrogenation of the polymer backbone. [27][28][29] Moreover, the ternary-coordinated nitrogen in the cyanide group permits some extent of chemisorption due to its partial basicity,w ithoutt he necessity for high heat of regeneration, as it is required for amines. [30] Severals tudies have shown that different nitrogen-bearing species are formed depending on the temperature applied during the heat treatment and that their chemical nature influences the extent of CO 2 capture.…”