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Controlled Preparation and Properties of Hydrogels Containing Lactate Groups

Author: XuJing
Tutor: XiaoCongMing
School: Huaqiao University
Course: Applied Chemistry
Keywords: Lactate-groups hydrogel preparation properties controllable
CLC: O648.17
Type: Master's thesis
Year: 2013
Downloads: 2
Quote: 0
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Abstract


In this paper, non-toxic and cheap lactic acid was allowed to react withpolyethylene glycol for preparing a diol (LEG). Then, an unsaturated macromonomer(LEM) was obtained via the esterification reaction between LEG and maleicanhydride. Similarly, PVA-based macromonomer (PVAM) was synthesized fromwell-defined PVA. The macromonomers were cross-linked to generate hydrogelscontaining lactate groups. The structure and properties of the hydrogels wereinvestigated, and the results are summarized as follows:1. pH-responsive hydrogels containing lactate groups (VLEH) were obtainedthrough the esterification reaction between LEM of different molecular weights andwell-defined PVA. The hydrogels were also tailored by controlling the feeding ratioof LEM and PVA. The structure and morphology of the gels were characterized withFTIR, TGA, DSC and SEM. It was found that the swelling ratio of the gels reachedthe maximum when they are placed in alkaline solution. The properties of VLEHwere changed with varying the ratio of PVA:LEM. The swelling ratio of gels in PBSwas in the range between1.73-5.29. The loading capacities of gels for rhodamine Bcould be24.12to79.78mg/g. And the adsorption capacities of gels for ferric ionwere157-927mg/L. In addition, the release rate of rhodamine B from the gelsdepended on the ratio of PVA:LEM as well.2. LEMA and LEMAI hydrogels were prepared by the radical cross-linkingreaction of LEM and acrylic acid (AA), or LEM, AA and itaconic acid (IA)respectively. The structure and properties of the gels were characterize with FTIR,TGA, DSC, fluorescence microscopy, scanning electron microscopy and dynamicmechanical testing. The swelling rate was controllable by adjusting the feeding ratio.The swelling ratios of LEMA and LEMIA gel, which obtained by using the ratio ofAA: LEM and IA: AA was0.5:1and1:1respectively, followed the cycle of low, highand low when the gels were maintained in acidic, basic and acidic buffer solution.LEMA gel could efficiently adsorb the heavy metals lead, copper, and cerium ions.The adsorption capacity increased with increasing the amount of AA used to prepareLEMA. LEMA gel showed the ability to adsorb ions again. It was found that the adsorption capacity for lead ion is higher than those for the other two kinds of ions.Interestingly, LEMA gel became turbid after it adsorbing calcium ion, which might beattributed to the variation of the network.3. Another kind of lactate groups-contained hydrogel (VMLEH) was preparedvia the radical cross-linking reaction between the macromonomer PVAM and LEM.The structure and morphology of VMLEH were characterized with FTIR,TGA, DSC,DMTA, and scanning electron microscopy (SEM). The equilibrium swelling ratios ofVMLEH in a neutral buffer solution, the ability of embedding Rhodamine B withinthe gel and its release behavior were examined. The experimental results showed thatthe glass transition temperature, storage modulus, equilibrium swelling, embeddingcapacity, and releasing rate of VMLEH could be easily regulated.In a word, the esterification reaction and controlled radical polymerization wereapplied to synthesize the intermediates. The convenient esterification and commonradical reaction were adopted to form a variety of hydrogels containing lactate-groups.The structure and properties of the gels could be controlled with changing the amount,molecular weight and structure of reactants. The presented results are useful fordeveloping hydrogels for some applications.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Colloid chemistry ( physical and chemical dispersion system ) > Colloid > Gel and soft
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