Assembly Regulated Morphology Study Of Polymer—Core-Shell Structuralacidic Ionic Liquid And Study Of OrganotinPolymer

Currently, the alkaline catalystsare mainly used in the industrial synthesis of biodiesel.But it requires high quality of raw material, namely, the content of free fatty acids and water in the raw material must be controlled in a very low level.Otherwise, saponification reaction is easy to occur. It will influence the yield of biodiesel. In comparison, the catalytic efficiency of acidic catalysts are lower than alkaline catalysts, and it has requirement for the higher molar ratio of alcohol to oil and higher reaction temperature in the case of acidic catalysts, but the acid catalysts can catalyzeboth the esterification of free fatty acids and the transesterification of oils simultaneously without saponification reaction. Among them, the inorganic liquid acid catalystsare usually used to catalyze the synthesis of biodiesel.However,it results in a large amount of industrial waste water and waste salt due to its non-recyclable used. Solid acid catalystscan be reused, and havesome applications in industry,but the leaching of solid acid leads to the additional cost for the separation and purification of product.With the development of green and sustainable chemistry, acidic ionic liquids have been developed. It possesses not onlythe catalytic properties of acidic catalyst, but also the characteristics of ionic liquid. And the acidic ionic liquids are incompatible with biodiesel, which make it easy to be separated from product and recycled. And thus it has attractedmore and more attention of chemists. Due to the strong hydrogen bond actionbetween the water or glycerol and acidic sites, the acid catalystsare prevented to interact with substrates, andthus the catalytic effect decreases. Therefore, to improve the catalytic performance of acid catalyst, it is necessary toincrease the hydrophobicity of the acidic catalysts surface and prevent the adsorption of water or glycerol on the activity site, and then realize the highly efficient synthesis of biodiesel. The acidic ionic liquids developed are soluble in short chain alcoholsfor the synthesis of biodiesel at present. Thus the recovery of catalystsis still relatively more troublesome. It needs to remove unreacted alcohols under vacuum, and then remove water and glycerol produced in the esterification and transesterification by vacuum distillation. In view of this, hydrophobic PS shell protected polymer supported acid ionic liquids was herein designed and synthesized, which can not only provide hydrophobicenvironment, but also facilitate the recycling of the catalysts. This core cross-linked polymer supported acidic ionic liquids (pyridine sulfonic acid) were synthesized based on the self-assembly of PS-b-P4VP in toluene with1,4-dibromobutane as crosslinker, and applied to catalyze the esterification of long chain fatty acids and thetransesterificationof glycerol tripalmitate for the synthesis of biodiesel. The core cross-linked acidic ionic liquids can efficiently catalyze the esterification of long chain acids. And more longer the PS chain, more better the catalytic effect. Such catalysts can still remain the high catalytic activity with over80%yield of ester producteven after beingreused for six times. In addition, water resistance of the catalystsare significantly enhanc’ed compared to small molecular acid ionic liquid, even if the system containing10%water (corresponding to the total weight of reaction system), also can get the ester product with90%yield in the esterification of the long chain fatty acid and methanol. And simultaneously, the catalysts can also catalyze the transesterification of glycerol tripalmitate,and the newly ester can be obtained in99%yieldat optimized conditions.On the other hand, the development of polymerization method and characterization technique promotes the synthesis of various block copolymers and the study on the self-assembly morphology of block copolymers. Through the living controllable polymerization method,the block copolymer can be synthesized with narrow molecular weight distribution, confined structure and function. Self-assembly of block copolymer in bulk, film and solution can form many regular aggregates. And the driving force of self-assembly of block copolymers mainly comes from the incompatibility of blocks. Besides, the non-covalent interaction can also drive to the self-assemble of block copolymer to form various morphologies, which can be reversibly regulated by changing the non-covalent interaction. With this in our mind, the block copolymers containing organotin carboxylates were synthesized. Using the poly(methyl methacrylate)(PMMA) as chain transfer agent, the organotincarboxylate was successfully introduced into the polymer via the RAFT (Reversible Addition Fragmentation Chain Transfer Polymerisation) polymerization on the condition that the polymerization concentration of acetyl dibutyltin methacrylate was strictly control. Due to the strong coordination between the oxygen of carboxyl group and tin atom, the free polymer chainsproceed self-assemble to form the aggregates. To the best of our knowledge, the self-assembly driven by coordination is mainly based on thcblending of the side chain ligand carrying block copolymers with additional metal ions in the previous reports. Here, the ligand and coordination center were simultaneously introduced into polymer chain using RAFT polymerization of organotin monomer. And we focus on the morphology study driven by coordination and the regulation of the assembly by adding dibutyltin dichloride using TEM and DLS analysis method. Notably,organotin carboxylate can catalyze the transesterification reaction, but the toxicity of the organotin limits its application. Considering that the organotin carboxylates loaded on the polymer can be recycled conveniently, and avoid product contamination. The catalytic activity of organotincontaining block copolymers was also investigated in the tranesterification of glycerol tripalmitate for the synthesis of biodiesel. As a result, the ester product could be obtained with78%yield at optimized conditions.