Poly(styrene-maleic anhydride) copolymers (SMA®) are a highly versatile copolymer class, containing both hydrophobic moieties (styrene) and reactive, functionalizable moieties (anhydride).
The properties of the base polymer are determined by the ratio of styrene to maleic anhydride and by the molecular weight. SMA® native resins are amorphous thermoplastic polymers that are very transparent and exhibit high heat resistance and dimensional stability.
The specific reactivity of the anhydride in SMA® enables a rich library of post-polymerization modification possibilities. These range from simple hydrolysis resulting in water-soluble polymers, to (di)esterification and amide- and imide-formation, enabling high control of polymer properties over a broad range of (water) solubilities, glass transition temperatures, and melt viscosities. While the anhydride is still reactive, its hydrolytic sensitivity to atmospheric moisture is significantly lower than non-polymeric anhydrides.
Thanks to these unique properties, SMA® has a diverse range of applications, from heat booster in polymer blends to dispersing agent and coatings ingredient.