Preparation And Properties Study Of Pyridine Coordination Shape Memory Polyurethane

Shape memory polymer is a kind of intelligent material which is different from shape memory alloy.At present,there are many researches on shape memory polymers.Polyurethane shape memory polymers are one of the most popular shape memory polymer However,shape memory properties of the current shape memory polyurethanes are too single,and there are few triple or multiple shape memory effects,and reshaping shape memory performance,etc.,and basically does not have reshaping performance.This greatly limits the applications of shape memory polymers.The introduction of coordination bonds to prepare metallo-supramolecular shape memory polymeric materials is a new research frontier.In the coordination metallo-supramolecular shape memory polymer based on its metallo-coordination bond,the distribution of soft segments and hard segments in the molecular structure of the polymer might be changed.The dynamic reversible cross-linking coordination bond also provided structure foundation to the remodeling of the metallo-supramolecular polymer.Therefore,in this thesis,we synthesize a series of coordination metallo-supramolecular polymurethanes with excellent shape memory properties,which realizes double or even multiple shape memory properties and excellent reshaping properties,and we also analyzes the mechanism of reshaping memory effects carefully.Firstly,the side chain coordination metallo-supramolecular shape memory polymer was prepared by reacting N,N-dihydroxyethylisonicotin（BINA）with1,4-butanediol（BDO）and hexamethylene diisocyanate（HDI）.Then,a type of side chain coordination metallo-supramolecularr shape memory polymers（B-MPUs）are prepared by feeding of CuCl₂ upon heating.The results show that thermal stability of B-MPUs is improved and the molecular interaction between polymer chains is improved greatly.The B-MPUs thus form good micro-phase separation structure with excellent shape memory properties and good mechanical properties.However,due to its narrow glass transition,the coordination metallo-supramolecularr polymer does not have good triple shape memory properties in B-MPUs.Secondly,A type of side chain type metallo-supramolecularr shape-memory polymer was also prepared by reacting 2,6-pyridine dimethanol（PDM）,which contains pyridine structure,with HDI and BDO.By adjusting the amount of PDM,a series of main chain pyridine type polyurethane（P-PUs）was firstly synthesized and we carefully studied the influence of PDM segments on the structure and properties of olyurethane polymers.Thereafter,another type of metallo-supramolecular shape memory polyurethane（P-MPUs）were also prepared by introducing Ag element to P-Pus,and they form coordination bond with the pyridyl group in the main chain.The result also found that the main-chain type of metallo-supramolecular polyurethanes have good shape memory properties,showing double and triple shape memory properties.Moreover,the P-MPUs was found to show excellent reshaping performance.A renewed permanent shape can be reshaped by heating to 110 ^oC without contact with water,and then the sample with new permanent shape can also start a new shape memory process.Finally,a series of aminopyridine type metallo-supramolecular shape memory polymer（D-PUs）were synthesized from 2,6-diaminopyridine（DAP）,PEG1000 and HDI.The role of DAP as chain extender in the polyurethane was firstly explored with DSC,TGA and DMA.Then the metallo-supramolecular polymer of D-MPUs was synthesized by adding Fe（III）.All results show that the D-MPUs have better thermal stability and better shape memory performance as compared with the the D-PUs samples.They show double shape memory effect and good reshaping memory performance.We also found that the introduction of coordination bonds to metallo-supramolecular polymer displays a certain hindrance to the water absorption.The research work in this thesis will provide important research ideas for the study of novel coordination supramolecular shape memory polymers and lay a material foundation for promoting the application of shape memory polymers in intelligent manufacturing of complex shapes.