A chemical process that allows color images to be printed on specially coated paper and then erased so that different images can be printed on the same paper has been developed by researchers at Rice, Yonsei and Korea universities.
The researchers explain the technique in a paper that will be published in the Aug. 4 issue of the journal Advanced Materials, which will feature images printed with this process on the cover.
The technique makes use of structural colors, which have different properties than the ink dyes used for standard printing. The standard dyes absorb all the colors of the spectrum except for the color that is visible to the eye, such as red or blue, and the colors fade over time. Structural colors are determined by the selective reflections of certain colors at certain angles. They’re made from one-dimensional stacks of layered polymers, called block copolymers.
“Copolymers are soft, stretchable and deformable,” said Ned Thomas, Rice’s Ernest Dell Butcher Professor of Engineering and professor of materials science and nanoengineering, of chemical and biomolecular engineering and of chemistry. “You can swell or shrink them and change their shape and dimensions, which will affect which color they reflect.”
Thomas said one of his former Ph.D. students at MIT, Cheolmin Park, who is now a professor at Yonsei University, wanted to collaborate on developing printable and rewritable copolymer structural colors.
The researchers found that they could use a single, colorless, water-based ink based on ammonium persulfate (APS) to control how the copolymers cross-link in various locations, which impacts their subsequent thickness and hence the structural colors that are reflected. APS stops the swelling of the copolymers, and the thin layer reflects blue. Ethanol was used to thicken the copolymers, which reflected red. By applying varying amounts of ethanol and APS to paper that is coated with copolymers, the researchers were able to control the swelling and shrinking of the molecules and generate the colors and patterns needed to create a picture. Large amounts of APS stopped all swelling, which resulted in black images because there was no reflection.
The researchers also discovered that applying hydrogen bromide to the paper removed or erased the APS, so the reflections were neutralized, which “reset” the system so that the paper could be used again. They printed and erased images more than 50 times on the paper, with resolution similar to that of a commercial office inkjet printer.
Thomas said refinements will be needed before this technique is commercially viable. Because ethanol evaporates, the reflective patterns disappear, so the researchers are looking for a substance that is less volatile and will maintain the colors indefinitely. They also need to find an alternative to hydrogen bromide, which is toxic and not environmentally friendly.
Thomas thinks the technique has the potential to be cost-effective because it will require only one ink — the APS — and a modified inkjet printer that uses paper coated with copolymers, which should cost “pennies per sheet,” he said. “This could be really useful when you want to reconfigure, recolor and reshape messages on signs or clothing.”
In addition to Thomas and Park, co-authors of the paper included Han Sol Kang, Jinseong Lee, Suk Man Cho, Tae Hyun Park, Min Ju Kim, Chanho Park, Seung Won Lee, Kang Lib Kim and Du Yeol Ryu, all of Yonsei University, and June Huh of Korea University.
The Latest on: Printable and rewritable copolymer structural colors
- MRRF 17: True Color 3D Printingon January 27, 2020 at 4:00 pm
A few years ago, a two-color frog print would have been impressive, but this isn’t the case anymore. The Midwest RepRap Festival is all about the bleeding edge of what 3D printers are capable of ...
- Materials To Know: Acetal And Delrinon January 27, 2020 at 4:00 pm
When you buy acetal without a trade name attached, you are usually purchasing acetal copolymer ... it’s just not possible If you need POM in a color other than black and natural, it has been ...
- Inside the Design of NYC’s Most Stylish New Restauranton January 16, 2020 at 11:54 am
“When we began working in the space Veronika inhabits, it was a demolished shell with inspiring structural bones which ... points of light”), a natural color palette, pale oak floors, wood ...
- Item #: ZG-0805-0301-E-B GUARDIAN 805 Caseon January 9, 2020 at 4:00 pm
High-strength Injected Copolymer Polypropylene Structural Resin Construction Temperature Rating of -27.4/+194°F -33/+90°C Certified up to 1M Depth to IP67 Case, Latches & Handles Resistant To Any Kind ...
- Multifunctional materials for implantable and wearable photonic healthcare deviceson January 7, 2020 at 9:20 am
Numerous light-based diagnostic and therapeutic devices are routinely used in the clinic. These devices have a familiar look as items plugged in the wall or placed at patients’ bedsides, but ...
- Method erases color printing and reuses the paperon July 31, 2019 at 5:00 pm
wanted to collaborate on developing printable and rewritable copolymer structural colors. The researchers found that they could use a single, colorless, water-based ink based on ammonium ...
- Deluxe Corp (DLX) CEO Barry McCarthy on Q1 2019 Results - Earnings Call Transcripton April 25, 2019 at 12:54 pm
Before I get into the details on our strategy and progress, let me turn the call over to Keith for some additional color on the quarter ... We believe we have structural savings that will largely ...
- Rewritable paper goes technicoloron January 8, 2018 at 4:00 pm
The paper industry has a significant environmental impact, from cutting down trees for raw material to consuming large amounts of energy and water to process that material. To curb that impact ...
- Technique enables printable and rewritable color imageson July 31, 2017 at 5:00 pm
The researchers explain the technique in a paper that will be published in the Aug. 4 issue of the journal Advanced Materials ("Printable and Rewritable Full Block Copolymer Structural Color"), which ...
- EU poultry industry to study feather-based plastics packagingon June 8, 2017 at 6:46 am
But those feathers also are an important source of keratin — a tough, fibrous, structural protein that ... be incorporated in the form of fiber and copolymer in the composite's matrix.
via Google News and Bing News