In order to obtain a crosslinked cellulose without derivatization, a polymer according to an embodiment of the present disclosure is a polymer having a structure in which cellulose substantially represented by the following formula (c1) is crosslinked with a polyfunctional epoxy compound:

##STR00001##

wherein in the formula (c1), n represents an integer of 2 or more.

In order to obtain a crosslinked cellulose without derivatization, a polymer according to an embodiment of the present disclosure is a polymer having a structure in which cellulose substantially represented by the following formula (c1) is crosslinked with a polyfunctional epoxy compound:

##STR00001##

wherein in the formula (c1), n represents an integer of 2 or more.

A carrier for ligand immobilization obtained by shrinking polysaccharide porous beads not less than 10% by a shrinkage rate defined by the following formula, and crosslinking the polysaccharide porous beads: Shrinkage rate (%)=(1V.sub.2/V.sub.1)100 (wherein, V.sub.1 indicates the gel volume of polysaccharide porous beads before shrinkage, and V.sub.2 indicates the gel volume of polysaccharide porous beads after shrinkage).

A carrier for ligand immobilization obtained by shrinking polysaccharide porous beads not less than 10% by a shrinkage rate defined by the following formula, and crosslinking the polysaccharide porous beads: Shrinkage rate (%)=(1V.sub.2/V.sub.1)100 (wherein, V.sub.1 indicates the gel volume of polysaccharide porous beads before shrinkage, and V.sub.2 indicates the gel volume of polysaccharide porous beads after shrinkage).

The present disclosure provides a method for preparing an aerogel or a foam, the method comprising: forming a reaction mixture comprising a cellulose nanofibril gel, a first solvent, and one or more crosslinking agents under conditions sufficient to crosslink the gel; and contacting the crosslinked gel with a second solvent under conditions sufficient to dry the crosslinked gel, thereby forming an aerogel or foam.

A pulp in accordance with a particular embodiment includes crosslinked cellulose fibers. The pulp can have high brightness, reactivity, and intrinsic viscosity. The pulp, therefore, can be well suited for use as a precursor in the production of low-color, high-viscosity cellulose derivatives. A method in accordance with a particular embodiment of the present technology includes forming a pulp from a cellulosic feedstock, bleaching the pulp, crosslinking cellulose fibers within the pulp while the pulp has a high consistency, and drying the pulp. The bleaching process can reduce a lignin content of the pulp to less than or equal to 0.09% by oven-dried weight of the crosslinked cellulose fibers. Crosslinking the cellulose fibers can include exposing the cellulose fibers to a glycidyl ether crosslinker having two or more glycidyl groups and a molecular weight per epoxide within a range from 140 to 175.

A pulp in accordance with a particular embodiment includes crosslinked cellulose fibers. The pulp can have high brightness, reactivity, and intrinsic viscosity. The pulp, therefore, can be well suited for use as a precursor in the production of low-color, high-viscosity cellulose derivatives. A method in accordance with a particular embodiment of the present technology includes forming a pulp from a cellulosic feedstock, bleaching the pulp, crosslinking cellulose fibers within the pulp while the pulp has a high consistency, and drying the pulp. The bleaching process can reduce a lignin content of the pulp to less than or equal to 0.09% by oven-dried weight of the crosslinked cellulose fibers. Crosslinking the cellulose fibers can include exposing the cellulose fibers to a glycidyl ether crosslinker having two or more glycidyl groups and a molecular weight per epoxide within a range from 140 to 175.

A carrier for ligand immobilization obtained by shrinking polysaccharide porous beads not less than 10% by a shrinkage rate defined by the following formula, and crosslinking the polysaccharide porous beads: Shrinkage rate (%)=(1V.sub.2/V.sub.1)100 (wherein, V.sub.1 indicates the gel volume of polysaccharide porous beads before shrinkage, and V.sub.2 indicates the gel volume of polysaccharide porous beads after shrinkage).

A carrier for ligand immobilization obtained by shrinking polysaccharide porous beads not less than 10% by a shrinkage rate defined by the following formula, and crosslinking the polysaccharide porous beads: Shrinkage rate (%)=(1V.sub.2/V.sub.1)100 (wherein, V.sub.1 indicates the gel volume of polysaccharide porous beads before shrinkage, and V.sub.2 indicates the gel volume of polysaccharide porous beads after shrinkage).

There is provided a package material comprising an oxygen barrier polymer film, wherein the film comprises a polymer obtainable by a process comprising the steps of: a) oxidizing cellulose fibers to ultimately obtain cross-linked cellulose; and b) homogenizing the product of step a) to obtain fibrils in a width range of 1 nm to 150 nm. A corresponding use is also provided.