Shape-memory polymers (SMPs) are a class of materials that are able to “remember” one or more shapes, and can be “frozen” into a temporary shape under stress, temperature, or electrical voltage. By applying some stimulus, such as heat, magnetic field, UV radiation, etc., they can recover their original shape through the internal elastic energy.
There are many applications of SMPs in the field of bio-medical, structural parts and textile, which make the SMPs one of the hottest topics in both academic and industrial society. The advantages and the disadvantages of thermoplastic SMPs are obvious that they are easy of processing but the recovery property is not satisfied. Researchers have been investigating for this challenge for a long time.
|Fig. The Recovery Process of SMPU in 3 Minutes after its Elongation of 800%|
Recently, Prof. Jin Zhu’s group at NIMTE developed a bio-based SMP material by substituting petroleum based chain extender with rosin based one. With the careful molecular design, they constructed highly incompatible hard and soft segments along the polymer chain and obtained shape-memory polyurethane (SMPU) with supreme shape recovery property.
This SMPU can ‘remember’ 96% of original length after 1000% strain treatment, and is able to reach 960% of the maximum shape recovery, which is more than two times of the maximum value reported as 400%. All the above results has been published in Journal of Materials Chemistry A (2013, 1(10): 3263-3267.) under the Royal Society of Chemistry.
Professor Jin Zhu
Source: Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), press release, 2013-03-05.