Abstract
In this work, small molecule diols named PEMTC were synthesized from isophorone diisocyanate, N-(2-hydroxyethyl)acrylamide and trimethylolpropane by a semi-directional method. PEMTC (2-(prop-2-enamido)ethyl N-{3-[({[2-ethyl-3-hydroxy-2(hydroxymethyl)propoxy]carbonyl}amino)methyl]-3,5,5-trimethylcyclohexyl}carbamate) contains hydrogen bond active site and light-initiated C=C. We introduced it as a branch chain block into poly(ε-caprolactone) (PCL). By feeding and monitoring the reaction process, we synthesized a large number of polyurethane elastomers, hydrogen bonds PCL-based elastomer (HPE), which contain a large number of dynamic hydrogen bonds. Under UV irradiation, PEMTC can make HPE molecules aggregate and cross-link, improve the degree of internal hydrogen bonding interaction of HPE materials and endow HPE materials with good elasticity, toughness, heat resistance and shape memory ability. After 270 nm UV irradiation, the elongation at break of HPE materials decreased from 607.14–1463.95% to 426.60–610.36%, but the strength at break of HPE materials increased from 3.36–13.52 to 10.28–41.52 MPa, and the toughness increased from 16.36–129.71 to 40.48–172.22 MJ m−3. In addition, the highest shape fixation rate of HPE after UV irradiation was 98.0%, and the recovery rate was 93.7%.
Highlights
Shape memory polymers are a kind of material that can give one or more temporary shapes and can be returned to the initial state by external field stimulation, such as heat [1,2], electric [3,4], solvent [5], magnetic field [6,7], humidity [8,9], light [10,11] and pH [12,13]
Because the primary -NCO group in the isophorone diisocyanate (IPDI) molecule is hindered by the cyclohexane ring and the α-substituted methyl group, the secondary -NCO group attached to the cyclohexane is more reactive than the primary -NCO group
During the synthesis of PEMTC and hydrogen bonds PCL-based elastomer (HPE), under the condition of a slight excess of IPDI, as the synthesis reaction proceeds, the -NCO content in the system will gradually decrease as the reaction proceeds, and the secondary -NCO in IPDI is mainly consumed
Summary
Shape memory polymers are a kind of material that can give one or more temporary shapes and can be returned to the initial state by external field stimulation, such as heat [1,2], electric [3,4], solvent [5], magnetic field [6,7], humidity [8,9], light [10,11] and pH [12,13]. When the polyurethane film is cured, the secondary cross-linking is initiated by UV irradiation, which makes a large number of hydrogen bonds get closer, improves the degree of hydrogen bond content in the hard segment and achieves the purpose of improving the SME of the material. This process can effectively improve the internal hydrogen bond aggregation of materials, save the amount of chain extender, reduce the raw material cost in the synthesis process and is of great significance to realize low-carbon and environmental protection in the material production process
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
