Modified biopolymers and methods of producing and using the same

A method for producing a cross-linked, charge-modified starch, the method comprising:

• melting a starch in the presence of a plasticizer to form a homogeneous reaction blend, wherein the plasticizer comprises water in an amount of at least 20% by weight of the starch and the homogeneous reaction blend is a single, continuous phase that comprises a plasticized starch;
• reacting the plasticized starch and a charge-modifying agent that includes at least one negatively charged moiety in the homogeneous reaction blend to form the charge-modified starch;
• and
• cross-linking the charge-modified starch to form the cross-linked, charge-modified starch,
• wherein the at least one negatively charge moiety is a carboxly, a sulfonate, a sulfate, and/or phosphate group;
• and
• wherein the cross-linked, charge modified starch has a net negative charge, is anionic, and has a charge density of greater than 5 meq/q, as measured by titration, for the at least one negatively charged moiety.

A cross-linked, charge modified starch, wherein the cross-linked, charge modified starch includes at least one negatively charged moiety and the cross-linked, charge modified starch is provided by reacting a starch with a charge-modifying agent including the at least one negatively charged moiety;

• wherein the cross-linked, charge modified starch has a charge density of greater than 5 meq/g, as measured by titration, for the at least one negatively charged moiety;
• wherein the cross-linked, charge modified starch has a net negative charge and is anionic;
• wherein the at least one negatively charged moiety is a carboxyl, a sulfonate, and/or a phosphate group;
• and
• wherein the cross-linked, charge-modified starch absorbs a 0.9% saline soluation, at room temperature, in an amount of at least 20times the weight of the cross-linked, charge-modified starch.

A cross-linked, charge modified starch, wherein the cross-linked, charge modified starch includes at least one negatively charged moiety and the cross-linked, charge modified starch includes at least one negatively charged moiety and the cross-linked, charge modified starch is provided by reacting a starch with a charge-modifying agent including, the at least one negatively charged moiety;

• wherein the cross-linked, charge modified starch has a charge density of greater than 5 meq/g, as measured by titration, for the at least one negativey charged moiety;
• wherein the cross-linked, charge modified starch has a net negative charge and is anionic;
• wherein the at least one negatively charged moiety is a carboxyl, a sulfonate, a sulfate, and/or a phosphate group;
• and
• wherein the cross-linked, charge-modified starch has a free swell capacity (FSC) in a range of about 25 g/g to about 100 g/g.

A cross-linked, charge modified starch, wherein the cross-linked, charge modified starch includes at least one negatively charged moiety and the cross-linked charge modified starch is provided by reacting a starch with a charge-modifying agent including the at least one negatively charged moiety;

• wherein the cross-linked, charge modified starch has a charge density of greater than 5 meq/g, as measured by titration, for the at least one negatively charged moiety;
• wherein the cross-linked, charge modified has a net negative charge and is anionic;
• wherein the at least one negatively charged moiety is a carboxly, a sulfonate, a sulfate, and/or a phosphate group;
• and
• wherein the cross-linked, charge-modified starch has a Centrifuge Retention Capacity (CRC) in a range of about 15 g/g to about 60 g/g.