MODIFIED BIOPOLYMERS AND METHODS OF PRODUCING AND USING THE SAM
Modified biopolymers, such as, charge-modified biopolymers, cross-linked biopolymers, and cross-linked, charged modified biopolymers are provided along with methods of producing and using the same.
1 . A method for producing a cross-linked, charge-modified biopolymer comprising:
combining a biopolymer and a plasticizer to form a homogenous reaction blend, wherein the homogenous reaction blend comprises a plasticized biopolymer;
reacting the plasticized biopolymer and at least one charge-modifying agent in the homogenous reaction blend to form a charge-modified biopolymer; and
cross-linking the charge-modified biopolymer to form a cross-linked, charge-modified biopolymer,
wherein the cross-linked, charge modified starch is free of crystalline domains.
2 . The method of claim 1 , wherein the combining step further comprises combining a catalyst with the biopolymer and the plasticizer to form the homogenous reaction blend.
3 . The method of claim 1 , wherein the cross-linking step further comprises reacting the charge-modified biopolymer with at least one cross-linking agent.
4 . The method of claim 1 , wherein the biopolymer comprises at least two different biopolymers.
5 . The method of claim 1 , wherein the cross-linked, charge-modified biopolymer has a net positive charge.
6 . The method of claim 1 , wherein the combining step comprises melt blending the biopolymer and the plasticizer using a reactive extrusion process.
7 . The method of claim 1 , wherein the method is carried out in an extruder.
8 . The method of claim 1 , wherein the cross-linked, charge-modified biopolymer is in the form of a particle have a diameter in a range of about 10 microns to about 1000 microns.
9 . The method of claim 1 , wherein the reacting and/or cross-linking step(s) is/are carried out at a temperature in a range of about 80° C. to about 150° C.
10 . The method of claim 1 , further comprising heating the cross-linked, charge-modified biopolymer at a temperature in a range of about 100° C. to about 150° C. for a period of time in a range of about 1 minute to about 8 hours.
11 . The method of claim 1 , wherein the cross-linked, charge-modified biopolymer has a net negative charge.
12 . The method of claim 11 , wherein the cross-linked, charge-modified biopolymer includes at least one negatively charged moiety selected from the group consisting of a carboxyl, sulfonate, a sulfate, and phosphate.
13 . A cross-linked, charge-modified biopolymer prepared according to the method of claim 1 .
14 . The cross-linked, charge-modified biopolymer of claim 13 having a charge density of at least 3 meq/g as determined by titration.
15 . A cross-linked, charge-modified biopolymer, wherein the cross-linked, charge- modified biopolymer is cationic, wherein the cross-linked, charge-modified biopolymer is free of crystalline domains, and wherein the biopolymer is starch.
16 . The cross-linked, charge-modified biopolymer of claim 15 , wherein the cross-linked, charge-modified biopolymer has a degree of substitution of at least 0.1, as measured by nitrogen content.
17 . The cross-linked, charge-modified biopolymer of claim 15 , wherein the cross-linked, charge-modified biopolymer includes at least one positively charged moiety selected from the group consisting of a quaternary ammonium, sulfonium, and/or phosphonium group.
18 . A cross-linked, charge modified biopolymer, wherein the cross-linked, charge modified biopolymer is anionic and wherein the cross-linked, charge modified biopolymer is free of crystalline domains, and wherein the biopolymer is starch.
19 . The cross-linked, charge-modified biopolymer of claim 18 , wherein the cross-linked, charge modified biopolymer has a degree of substitution of at least 0.1, as measured by nitrogen content.
20 . The cross-linked, charge-modified biopolymer of claim 18 , wherein the cross-linked, charge-modified biopolymer includes at least one negatively charged moiety selected from the group consisting of a carboxyl, sulfonate, a sulfate, and phosphate.