No limit to number of times material can change shape
Although most materials slightly expand when heated, there is a new class of rubber-like material that not only self-stretches upon cooling; it reverts back to its original shape when heated, all without physical manipulation.
The findings were recently published in the journal ACS Macro Letters.
The material is like a shape-memory polymer because it can be switched between two different shapes. “However, unlike other shape-memory polymers, the material does not need to be programmed each cycle—it repeatedly switches shapes, with no external forces, simply upon cooling and heating,” said Mitchell Anthamatten, an associate professor of chemical engineering.
Anthamatten and his team built on the success of a recently developed polymer that can also stretch when cooled. The other polymers need to have small loads—or weights—attached in order to direct the shape to be taken. That is not the case with the Rochester polymer, because Anthamatten’s team “tricked it into thinking” a load was attached.
To carry out their strategy, the researchers introduced permanent stress inside the material. They began with polymer strands that were loosely connected by bonds called crosslinks that create a network of molecules. The material was stretched with a load attached to give it the desired shape. At that point, they added more crosslinks and cooled the polymer, causing crystallization to occur along a preferred direction.
Anthamatten’s team showed that internal crystallization forces are strong enough to stretch the material along one direction. Once cooled below about 50 °C, polymer chain segments pack into highly ordered micro-layers called lamellae. This reorganization occurs within a network of polymer chains, causing the material’s length to increase by over 15 percent.
“The stress we built into the network takes the place of the load and enables the material to ‘remember’ the shape it will assume when it’s later cooled without a load,” said Anthamatten.
Conventional shape-memory polymers need to be reprogrammed after each cycle, but that’s not the case with the material developed by Anthamatten and his team. After multiple cycles of cooling and heating, they found that the material assumed its programmed shape and returned to its initial state with no noticeable deviation.
The Latest on: Shape-memory polymer
via Google News
The Latest on: Shape-memory polymer
4D Printing of Recyclable Lightweight Architectures Using High Recovery Stress Shape Memory Polymer
on May 20, 2019 at 2:30 am
High-performance lightweight architectures, such as metallic microlattices with excellent mechanical properties have been 3D printed, but they do not possess shape memory effect (SME), limiting their ... […]
Shape memory alloy makes moves for micro-robots
on May 16, 2019 at 6:30 am
Shape memory alloys have the ability to “remember” their shape ... Thin films of metal, such as nickel, titanium or copper, layered on a transparent polymer, are deposited onto a substrate using a ... […]
Polymer Chameleons Market Opportunities 2019, Research Size, Share, Global Segment, Top Companies, Regional Analysis and Forecast to 2023
on May 9, 2019 at 5:05 am
Based on the Product Type the market is segmented into Thermo-Responsive polymers, Photo-Responsive polymers, Shape Memory polymers, Electroactive & Magnetically-Responsive polymers, pH-Responsive ... […]
Global Smart Polymers Market 2018- Covestro, BASF, Honeywell International
on May 8, 2019 at 9:33 pm
this Smart Polymers business report displays the production, revenue, price, market share, and growth rate of each type, primarily split into- " Shape Memory Polymer Electroactive Polymer Self-Healing ... […]
New shape-memory polymer may enable medtech breakthroughs
on February 28, 2019 at 1:29 pm
A new type of shape-memory polymer (SMP) that changes its shape in response to exposure to enzymes and is compatible with living cells could represent a medical breakthrough. SMPs typically require ... […]
Enzymes prompt shape memory polymer to take form in medical applications
on February 27, 2019 at 12:41 am
A new kind of shape memory polymer could have major implications for health care, claim researchers at Syracuse University’s College of Engineering and Computer Science. Prof James H. Henderson and Ph ... […]
Engineers create rubbery 'smart' material to treat open wounds, infections and cancer
on February 26, 2019 at 2:09 pm
Researchers have developed a material -- a new kind of shape memory polymer (SMP) -- that could have major implications for health care. Researchers in the Syracuse University College of Engineering ... […]
New shape memory polymer represents biomedical breakthrough
on February 26, 2019 at 7:14 am
Researchers in the College of Engineering and Computer Science have developed a material—a new kind of shape memory polymer (SMP)—that could have major implications for health care. SMPs are soft, ... […]
Neural Electrodes Snake Around Blood Vessels, Up Nerves
on January 30, 2019 at 8:06 am
Instead of nitinol, the team used a shape-memory polymer. The substance works in a similar way, but the change in shape is triggered by body temperature. Zhang and his colleagues constructed a ... […]
FDA approves medical device using shape memory technology
on August 6, 2018 at 8:04 am
The device integrates expanding shape memory polymer technology that was partly developed at Lawrence Livermore National Laboratory (LLNL). Much of the technology behind the device was developed at ... […]
via Bing News