| This paper designed and synthesized four amide groups-based low molecular weight organic gelators with different structural characteristics. And their relationship between structure and properties were investigated systematically through changing the influence factor of solvent, temperature and ultrasonic stimulation. Moreover, we introduced those gelators to modify PMMA by “in-situ” polymerization and investigated their performance. Specific studies and conclusion were as follows:1. Three different dendritic dendrons(Branch1(COOH), Branch2(COOH) and Branch3(COOH)) based on amide groups were successfully designed and synthesized. All of these dendritic dendrons owned a carboxylic acid at the focal point and possess different functional group on the periphery. They could form two-component gelators(B1…C8… B1, B2…C8…B2 and B3…C8…B3) through combination of dendritic dendrons and diaminoctane. The self-assembly behavior of the two-component gelators in organoic solvent was investigated by tube inversion method, rheology and SEM. The results indicated that B1… C8… B1 showed higher thermal stability and mechanical strength than others and it could be attributed to the B1… C8… B1 own more number of amide groups.2. The self-assembly behavior of a two-component gelator(B1…C12…B1) in MMA was depends on the ultrasonic stimulation and gelator concentration. Tube inversion method and rheology showed that sonication-induced-gel(S-gel) exhibited much higher gel–sol temperature, storage modulus and lower critical gelator concentration compared with temperature-induced-gel(T-gel).This could be attributed to sonication could partially destroy the hydrogen bond network and benefit the formation of the organogels.3. Three novel amide groups-based gelators were successfully designed and synthesized. In the structures, 1, 4-butanediamine was a linker, core was a benzene ring, and periphery was cholesteryl. According to the positions of the substituents on the benzene ring, the prepared compounds were denoted as Ortho-cholesterol, Meta-cholesterol, and Para-cholesterol, respectively. Tube inversion method and rheology showed that the positions of the substituents on the benzene ring were important for their gel ability. The order of thermal stability and mechanical strength was para-> meta- >ortho-. SEM showed that Meta-cholesterol and Para-cholesterol had formed integral gel network in MMA. After polymerization of MMA/ Meta-cholesterol gel, the self-assembled gel network modify PMMA could be obtained. Tensile, impact and optical properties tests showed that the modified PMMA had higher elongation at break and impact strength with lower transparency.4. Three kinds of amide dendritic gelators, G1-BOC, G2-BOC and G3-BOC, were synthesized, and their self-assemble behavior and into-modified PMMA were investigated. It could be observed that the thermal stability and mechanical strength of gels were increased with increasing degree of branching. IR and 1HNMR confirmed that hydrogen bond and hydrophobic effect were the driving force for self-assembling. Tensile, impact and optical properties tests showed that the selfassembled gel network modified PMMA had higher impact strength while retaining their high transparency.5. The dumbbell-like structure dendritic gelator(G1-alkyl) was successfully designed and synthesized. In the structures, L-lysine was a linker, core is 1, 12-Diaminododecane, and periphery was long-chain alkyl. Tube inversion method and rheology confirmed that G1-alkyl was a very effective gelator and it could form stable and transparent gels in MMA. SEM confirmed that G1-alkyl molecules spontaneously self-assembled into entangling fiber-like aggregates with diameter of 30-60 nm. After thermal polymerization of MMA gel, the self-assembling gel network could be integrated and homogeneous embedded into PMMA matrix. And the obtained PMMA nanocomposite showed higher impact strength and breaking elongation, while retaining their high tensile strength, storage modulus, Tg, light weight and high transparency. |
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