| This dissertation reported three type topologies (dendron, multi-"arms", three-dimensional radially symmetrical) of L-lysine based dendritic gelators. The relationship between structure and properties of the gelators, the effects of solvents, gel storage temperature and other external conditions on the gel properties as well as gelation mechanism were investigated. The self-assembling gelators were introduced into the PMMA matrix in order to assess its in situ modification of PMMA. Specific studies and conclusions are as follows:1. The first, second, third generation dendritic gelators Bzl-Gly-Lys(G1), Bzl-Gly-Lys(G2) and Bzl-Gly-Lys(G3) which contain a focus group of benzyl, a link unit of glycine, a branching unit of L-lysine were synthesised by divergent and convergent methods. HO-Gly-Lys(G1), HO-Gly-Lys(G2) and HO-Gly-Lys(G3) which have a focus group of carboxyl were obtained via hydrogenation reaction. Solvents investigation and variable temperature 1H NMR proved hydrogen bonding is the driving force of the gel; tube inversion method, DSC, rheology, ATR-FTIR, CD showed that the higher generation, the greater the strength of hydrogen bonding formed between the gelator molecules, the better of the thermal stability of the gel, and the higher of the mechanical strength. Fluorescence spectra showed benzyl provide π-π stacking force in the self-assembly process of the gel.2. Dumbbell-shape "two-arms" dendrimers G1-Cn-G1 and G2-Cn-G2 (n=6,9,12), and the regular tetrahedron type "four-arms" dendrimers based on pentaerythritol core PER-G1 and PER-G2 were synthesised by divergent and convergent methods. ATR-FTIR and CD showed that for G1-Cn-G1 system, the central carbon chain aims at providing a sparse solvent force, while for G2-Cn-G2 system, the central carbon chains play a assist role adjusting the organization of the "head" portion of the gelator; regular tetrahedron type "four-arms" dendrimers are needed to overcome a strong hindrance, therefore they are not as good as dumbbell-shaped "two-arms" dendrimers in gel capacity; POM and DSC proved that, G1-C12-G1/DCB gel contains spherulites network at low temperature, but it changes to fiber network at room temperature.3. A novel class of three-dimensional radially symmetric organic-inorganic hybrid gelator based on POSS and amino acid derivatives were synthesised and investigated. The results showed that POSS-Lys(Boc), of which "arms" containing two urethane bonds has the strongest gel ability. SEM, TEM, AFM showed that POSS-Lys(Boc) and POSS-Cys (Bzl) assembled into a unique "loofah-like" gel network. Tube inversion method indicated that the gel showes viscous flow state during heating process, rheology indicated that the gel has a strong resistance and recovery capabilities. XRD deduced that it adopts a segmented hexagonal aggregate mode.4. Gelator POSS-Lys(BOC) and Bzl-Gly-Lys(G3) self-assembled into nano/micro-scale gel network in MMA monomer. After UV radiation, a macro-homogeneous, microscopic phase separation PMMA/gel composite was formed. Compared to the pure PMMA, the composite has a higher elongation at break, and some debonding phenomenon occurs during the impact, the fracture surface is rough, DMA curves of the gel network has a loss peak of depolymerization. These phenomenas indicated that gel network can improve the toughness of PMMA material to some extent; the transmittance of PMMA/gel composite material substantially unchanged compared to the pure PMMA, the haze of composite increases with the gelator concentration increased; the frozen sectional SEM image of PMMA/gel composite after etching and the the mass spectral of the etching solution indicatied that the in-situ polymerization of MMA did not change the chemical composition of the gel factor and morphology of the gel network. This gel template extraction (Gel-Template-leaching) method can prepared molecularly imprinted polymer material with nano/micro scale. |
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