| Self-healing is an important way to get a new life or prolong life, for example skin can heal after the cut or the plant can regrow after peeling and so on. Inspired by biological materials, the concept of eliminating damage through a self-healing mechanism to enhance lifetime of material drew a lot of interests. In this paper, UPy-TMI functional monomer with quadruple hydrogen bonds was designed and synthesized. And we chose acrylic acid (AA) as an appropriate solvent to introduce the UPy-TMI functional monomer into the backbone of polymer. Then under the protection of the shielding effect of emulsifier, the hydrophobic UPy-TMI functional monomer was designed into aqueous emulsion to prepare the environmental latex film with self-healing property. We discussed the effect of the UPy-TMI functional monomer on latex films. In addition, we investigated the effects of thermal treatment temperature and time, content of functional monomer and glass transition temperature of the polymer films on their self-healing properties. The main ideas of this paper are as follows:1. In the anhydrous DMSO solution,2-amino-4-hydroxy-6-methyl pyrimidine (UPy) and 3-isopropenyl-a,a-dimethylbenzylisocyanate (TMI) react and get the UPy-TMI functional monomer with quadruple hydrogen bond and a double bond at the same time. Then we characterized the production by NMR and FIRT.2. Under the action of acrylic acid (AA), the MHB monomer was introduced into the backbone of the acrylic copolymer, while under the condition of suitable reaction temperature, DSB:PE-6100=2:1 emulsifier system and APS:SBS=1:1 initiator system, stable and less gel P(MMA-BA-AA-MHB) emulsion was achieved. Latex particles size and morphology were characterized by DLS and TEM and we found that the addition of functional monomer can cause closely array and not obviously size change of latex particles. Tgs of latex films were measured by DSC, and it was found that networks formed by multiple hydrogen bonds may lead to the increase of Tg. By water absorption tests, the water absorption of films was increased firstly and then decreased with the increase of the functional monomer content. The results of tensile tests showed that the films with more MHB content had higher tensile stress and lower elongation at break. About the self-healing property, with the increase of network density, the recovery rate increased firstly and then decreased, and got the optimum value at MHB monomer content of 2%.3. For the self-healing properties of latex films, we discussed the effect of thermal treatment temperature, time and glass transition temperature on it. Firstly, we fixed the thermal treatment time at 1 h, in order to determine the effect of thermal treatment temperature (60℃,80 ℃,90℃ and 100℃) on the self-healing property of the UPy-functionalized latex films, with the increase of thermal treatment temperature, the self-healing property got promoted and the tensile stress recovery rate got best value,94%, at 100℃. Then, we fixed the thermal treatment temperature at 100℃, in order to determine the effect of thermal treatment time (0.5h, 1h,2h and 4h) on the self-healing property. We got the conclusion that films had the best recovery rate at 1h and too short or too long time was not beneficial to self-healing. For different Tg of the latex films, under the same conditions, the films with lower Tg had better self-healing property, but they had similar results with the temperature and time. |
PDF Full Text Request