Synthesis Of The Self-Healing Hyderogen-Bonded Networked Supramolecular Elastomers

It's well known that animals have ability of self-healing, which encourages people to think about bringing this ability into materials to improve the service life. Among all the study of the self-healing materials, the hydrogen-bonded self-healing materials(H-SM) receive the extensive attention. The H-SM is formed by the elementary units under the force of the multiple hydrogen bonding, thanks to the reversibility of the hydrogen bond, the H-SM can possess the ability of self-healing.In this article, the hydroxyl hyperbranched polyester(HBP-OH) was prepared by the melt method, then the prepared HBP-OH was modified by the succinic anhydride(SA) to prepare the carboxyl hyperbranched polyester (HBP-COOH). In order to bring the azide group into the structure, HBP-COOH was reacted with diphenylphosphoryl azide (DPPA), then the azide group was changed into the isocyanate group by heating out of the nitrogen. Finally, the isocyanate group was reacted with diethylenetriamine (DETA) to bring the urea group and the amine group, which are strong hydrogen bonding forces, into the structure, the networked self-healing supramolecule was formed by the interaction of the hydrogen bonding forces. The detailed works are as follows:l.The HBP-OH was prepared from 1,1,1-trimethylolethane (TME) as B3 core molecule and 2,2-dimethylolpropionic acid(DMPA) as AB2 growing molecule, p-toluenesulfonic acid (p-TSA) as catalyst. Two monomer addition methods were studied, the methods are one-pot monomer addition(One-pot) method and slow monomer addition(Add) method, respectively. The results of the FTIR and 1H-NMR showed that the HBP-OH was successfully prepared, besides, the HBP-OH prepared by Add method possessed higher degree of branching.2. HBP-OH was modified by SA to get the HBP-COOH. Three methods were adopted. It was found that the reaction in bulk under high temperature could cause crosslinking easily, which could hardly get the HBP-COOH. And the second method, which was reacted in solvent under room temperature, requested long reaction time and large reagent, and it also caused waste. However, the last method, which was reacted by reflux, demanded shorter reaction time,and it could hardly cross link, besides, its use ratio of the reagent was high. The results of the FTIR and 1H-NMR showed that the HBP-COOH was successfully prepared.3. In order to prepare the self-healing hydrogen bonding supramolecular elastermers(H-SE), it was requested to bring the urea group and amine group into the structure. Two methods were used to prepare the target product. It was found that the first method, in which HBP-COOH was reacted with DETA and urea under high temperature, could destroy the hyperbranched structure, and the complex product was prepared. However, the second method, in which HBP-COOH was reacted with DPPA and DETA, could keep the hyperbranched structure and bring the target groups into the structure at the same time, and Hydrogen-bonding self-healing elastomers(H-SE) was finally proved successfully prepared by the FTIR and 1H-NMR. The effects of the concentration of the DETA on the mechanical, dynamic mechanical and self-healing properties of H-SE were studied. The experimental results showed that H-SE was soft and has self-healing property with the self-healing ratio at 67% when DETA concentration was low, while H-SE was hard and has higher mechanical property when DETA concentration was high.