New paper made from pollen can be printed and erased many times

Singapore researchers have designed a new paper that can be printed and erased up to eight times without sacrificing paper or print quality.

Environmentally friendly printing paper developed by Nanyang Technological University. (Photo: Nanyang Technological University)

The experimental material is being developed at Singapore's Nanyang Technological University using a variety of techniques. Similar to soap making, the papermaking process begins with the use of potassium hydroxide to remove the outer shell of the sunflower pollen grain. The soft substance inside the seed forms a gel. The researchers purified the gel with deionized water, then poured it into a flat mold and dried. After the gel dries into a 0.03 mm thick layer, they treat the finished product with citric acid so that the material is not affected by moisture.

The team's result is a soft paper that's lighter and more transparent than traditional pulp paper, but can still be put into laser printers and printed with conventional ink cartridges. Text and images remain on the paper even when tape is applied to the surface and removed, or when the paper is soaked in water.

However, if the paper is soaked in lye and gently rubbed for 2 minutes, the gel will swell, causing the ink layer to disintegrate and dissolve. At this time, the white paper will be soaked in ethanol for about 5 minutes to return the gel to its previous state. The paper is then dried and re-treated with acetic acid. Finally, the material can be ready for printing again without affecting the toughness or quality of the print. The whole process above can be repeated 8 times with each sheet of paper.

According to the team, another advantage of the new paper is that while traditional papermaking requires a lot of logging, the chalk they use can be collected continuously from fields of sunflowers. Pollen from plants such as camellias and lotus flowers can also be used in place of or in combination with sunflower pollen. The research team, led by professors Subra Suresh and Cho Nam-Joon, describes the product in detail in the journal Advanced Materials.