The self-organization of starch on paper

The objective of this study was to clarify how modified starch polymers self-organize on the surface of paper. Understanding this phenomenon could enable tailoring of the surface of paper with small amounts of polymer, thereby controlling and adjusting its surface chemistry and absorption properties. Native potato starch without depolymerization was modified with either hydrophilic or hydrophobic side chains, which were either neutral or anionic. These modified starches were applied to the paper surface by means of spray sizing. Starch penetration into the paper structure was reduced due to the high molecular weight of the native potato starch (Mw ≈ 2*106). Repulsion forces between the side chains of the anionically modified starch affected polymer elongation, paper surface oriented conformation, and paper coverage. The anionic side chains of the starch also experience repulsion from the anionic carboxylate ions of the base paper, which causes the side chains to orient themselves away from the paper. This selforganization phenomenon is most pronounced with a hydrophilic base paper with a high anionic charge. Modifying the chemical properties of the side chains makes it possible to control the surface energy of the base paper using an extremely low amount of polymer