Easy care, wrinkle-resistant cotton fabrics are one of the most widely manufactured and commonly used products in the world. Every individual on Earth uses these products every day of his/her life. Wrinkle recovery performance of untreated cotton fabric is poor because creases can be stabilized by intermolecular hydrogen bonds that easily break and reform in a creased configuration within the fiber during wetting/drying of the fabric. It's the same as what happens to spaghetti when it's boiled, then dried. When wet, the cotton cellulose (a polymer almost identical to the starch in spaghetti) becomes flexible. But when dried, it retains the shape in which it has been dried, due to the re-formation of hydrogen bonds.

To improve end-use performance, formaldehyde-based stabilizers are used to replace many of the hydrogen bonds in cellulose with permanent stronger covalent bonds called "crosslinks" that won't break when the fiber becomes wet. The original formaldehyde-containing crosslinkers from the mid 1900's suffered from poor stability, degraded strength (tear, tensile, and abrasion), and possible degradation of fabric during washing/drying. Even worse, they released airborne formaldehyde, a known human carcinogen. Later, a more stable crosslinker called DMDHEU became the industry standard. DMDHEU reduced many of these problems but notably did not completely eliminate the carcinogenic formaldehyde release.

Many alternatives to DMDHEU have been proposed and studied, but they all have eventually failed to be widely adopted for several reasons, i.e. environmental, health and safety issues; high cost; lower wrinkle recovery performance; strength degradation; and difficulty of application. These alternatives have mostly been low-molecular-weight reactive materials that could easily become airborne, thus releasing reactive pollutants that could affect the consumer in much the same way as formaldehyde.

We are stabilizing fabric for wrinkle resistance by a completely different chemical route that does not involve volatile materials that can become airborne and affect the consumer. Our basic strategy is to give cellulose an electrical

charge to make it "ionic" charged, then to treat it with high molecular weight polyelectrolyte polymers of opposite charge to lock the charged cellulose sites together with ionic (not covalent) crosslinks. This provides improved wrinkle recovery angle performance and also produces a consumer product with no hazardous chemical release. Our ionic crosslinks are intermediate in strength as shown in the following list (strength given in kilocalories per mol of bonds):



Hydrogen bonding (untreated cellulose)


Ionic crosslinking

(our method)


Covalent bonds (commercial crosslinkers)


We are investigating several methods ways to apply ionic crosslinking including the following:

Make the cellulose anionic (negative) then use polycation (positive) to crosslink

Make the cellulose cationic (positive) then use polyanion (negative) to crosslink

Make the cellulose anionic (negative), then cationic (positive) simultaneously

Make a pre-condensate from anionic (negative) any cationic (positive) material, then react with cotton

We have developed optimized methods for making cellulose ionic, either + or charged, using chloroacetic acid or 3-chloro-2-hydroxy-propyl trimethyl ammonium chloride. The first is indicated in Figure 1 below.