| A series of dendrimers were designed and synthesized by divergent method, whose structures were confirmed by 1H-NMR and Mass spectra (MS). The self-assembly behavior of the dendrimers in different solvents was researched. The dynamic mechanical properties and transparency of PMMA modified with gel network by"in-situ"polymerization were studied.The synthesis of the dendrimers1. The first generation dendrimer (G1-C12-G1) containing carbamate unit in terminal was synthesized from dodecane diamine and (S) - 2,6 - di-tert-butoxy carbonyl-aminocaproic acid in ethyl acetate solvent by amidation reaction2. The second generation dendrimer (G2-C12-G2) containing carbamate unit in terminal was synthesized from G1-C12-G1 and (S) - 2,6 - di-tert-butoxy carbonyl-aminocaproic acid in ethyl acetate solvent by amidation reaction3. The dendrimer (gelator-1) containing amide bond and double bond in terminal was synthesized from G1-C12-G1 and 3,5 - bis (2 - propylene -1- yloxy)benzoic acid in ethyl acetate solvent by amidation reaction The properties of dendrimer self-assemblyThe G1-C12-G1, G2-C12-G2 and gelator-1 self-assembling in methyl methacrylate (MMA), toluene, xylene, styrene solvents to form gels was investigated by tube inversion method. The results showed that gelator-1 and G2-C12-G2 have higher gel-sol temperature (Tgel) and lower critical gelator concentration, while, G1-C12-G1 has lower Tgel, and higher critical gelator concentration. The surface morphology of dried gels was studied by scanning electron microscopy (SEM), the results showed that gelator and the solvent is the key factors of gel network's size and shape. The PMMA modified with gel network by"in-situ"polymerizationG2-C12-G2 and gelator-1 were used as a gelator to modify PMMA by"in-situ"polymerization. The molecular weight (Mn) and molecular weight distribution width index (Mw/Mn) of the modified PMMA was tested with gel permeation chromatography (GPC), the results showed that molecular weight and the molecular weight distribution width index of the PMMA composite were scarcely influenced by incorporation of gel. The dynamic mechanical properties of modified PMMA was tested with DMA, the results showed that the modified PMMA have higher modulus, toughness and glass transition temperature(Tg) than pure PMMA. Finally the transparency of PMMA was tested by spectrophotometer, the results showed that the transparency of modified PMMA was scarely lower compared to pure PMMA. |
