浅析形状记忆聚氨酯弹性体

形状记忆聚氨酯弹性体是以软链段的结晶-熔融实现形状记忆功能，简述了形状记忆聚氨酯的设计要求，阐述了影响形状记忆的因素，最后简要介绍了形状记忆聚氨酯的应用。     

硬段结构对分子链含亲水基团的聚氨酯形状记忆性能的影响

采用自乳化法,用聚酯二元醇、二苯基甲烷二异氰酸酯(MDI)或异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)、乙二胺(EDA)、三羟甲基丙烷(TMP)等单体合成了分子链含亲水基团的聚氨酯.用FTIR对聚氨酯进行了结构表征,并测试了胶膜力学性能和形状记忆性能.主要探讨了硬段结构与质量分数,回复温度和多次拉伸-回复对聚氨酯形状回复率的影响.结果表明,聚氨酯分子链内引入苯环或化学交联结构,可以改善材料的力学性能和形状记忆性能;聚氨酯的硬段质量分数有一最佳值,达到此值形状回复率最大;不同硬段结构的聚氨酯达到最大形变回复率的临界硬段质量分数不同,硬段的结构越稳定,其在形状记忆聚氨酯中的质量分数越低.多次拉伸-回复可以提高形状记忆性能.     

溶液法合成形状记忆聚氨酯及其性能

以不同分子量的聚己二酸丁二醇酯(PBAG)为软段,2,4-甲苯二异氰酸酯(2,4-TDI)和1,4-丁二醇(1,4-BDO)为硬段,采用溶液聚合的方法合成具有形状记忆性能的聚氨酯,研究其形状记忆性能,并且用DSC分析不同的硬段含量聚合物的热行为.结果表明:以相对分子质量为3 000或以上的PBAG为软段,制得聚氨酯软段结晶,而且软段的结晶程度影响材料的形状记忆特性,软段的分子量越大,其形状记忆性能越好.     

形状记忆聚氨酯的结构与性能研究

以2，4-甲苯二异氰酸酯、不同相对分子质量的聚己二酸丁二醇酯(PBAG)和1，4-丁二醇为原料合成了一系列聚酯型聚氨酯弹性体。发现由相对分子质量为3000和5000的PBAG所合成的聚氨酯弹性体具有良好的形状记忆功能。通过DSC、弯曲试验和力学性能测试研究了形状记忆聚氨酯的性能，发现软段高度结晶和硬段聚集形成硬段微区是使聚氨酯具有较好形状记忆功能的必要条件。     

形状记忆聚氨酯的结构与性能研究

以2,4 甲苯二异氰酸酯(2,4 TDI),不同分子量的聚己二酸丁二醇酯(PBAG)和1,4 丁二醇(BDO)为原料合成了具有形状记忆功能的聚氨酯材料。通过DSC、弯曲实验和力学实验研究了形状记忆聚氨酯的性能,发现软段高度结晶和硬段聚集形成硬段微区是其具有较好形状记忆性能的必要条件。     

脂肪族形状记忆聚氨酯的合成及表征

以脂肪族异氰酸酯HDI为硬段原料合成了脂肪族的形状记忆聚氨酯,通过调节硬段含量研究了硬段结构对形状记忆性能的影响.DSC、DMA等分析结果表明,硬段含量的增加使软段结晶的不完善程度增大,并使硬段的结晶趋于完善,而软段结晶的完善程度决定了维持暂时形状的能力,所以形变固定率随着硬段增加而下降.同时IR结果证明,HDI形成的硬段间的氢键作用更强,从而得到了比芳香族形状记忆聚氨酯更高的形变回复率.     

形状记忆聚氨酯的研究与应用

聚氨酯（Polyurethanes,PUs)是一种多嵌段共聚物，可通过调节原料的组成和配比，得到性能各异的新型功能高分子材料，由硬段和软段组的PUs分子链，具有微相分离的本体结构，符合热致形状记忆高分子（TSMP）的条件，并具有良好的强度，硬度，耐磨性，耐挠曲性和生物相容性等优异性，可望在军事，航空及图书馆经济各项领域得到广泛应用。笔者概括了形状记忆PUs的记忆原理和特征，并对形状记忆PUs的研究现状和应用前景了重点阐述。     

第五十二讲 形状记忆聚氨酯高分子材料的研究进展

本文综述了形状记忆聚氨酯的研究进展,分别介绍了热塑性形状记忆聚氨酯、热固性形状记忆聚氨酯、复合改性形状记忆聚氨酯以及水性形状记忆聚氨酯,并且对形状记忆聚氨酯的应用领域作了简要概括,最后对形状记忆聚氨酯的发展方向进行了展望。     

形状记忆聚氨酯的研究进展

综述了形状记忆聚氨酯的形状记忆原理，介绍了形状记忆聚氨酯的研究现状及应用前景。     

聚酯型热致形状记忆水性聚氨酯的制备与性能研究

采用聚己二酸丁二醇酯(PBA)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)、三乙胺(TEA)、乙二胺(EDA)等单体,通过自乳化法合成了聚酯型热致形状记忆水性聚氨酯(TSMWPU)。利用偏光显微镜(POM)、差示扫描量热仪(DSC)、动态黏弹谱仪(DMA)和形状记忆性能分析等手段,探讨了不同分子量的PBA,以及不同异氰酸酯基与羟基的摩尔比(NCO/OH)对TSMWPU的结晶性能和形状记忆性能的影响。结果表明;增加PBA分子量,有利于软段结晶,从而提高TSMWPU的形状记忆性能;而增加NCO/OH值,则抑制了软段结晶,进而导致TSMWPU的形状记忆性能下降。     

Thiol-ene Reaction as Reversible Covalent Bond for the Design of Shape-Memory Polymers

Besides a stable phase, shape-memory polymers require an additional switchable moiety. In addition to thermal transitions and supramolecular interactions, these units can also be based on covalent bonds. Herein, the use of the reversible thiol-ene reaction as reversible cross-linker for the design of shape-memory polymers is demonstrated. A facile route to polymer networks with a thiol-ene acceptor and a comonomer (butyl methacrylate or 2-ethylhexyl methacrylate) cross-linked by dithiols is introduced. The thermal and mechanical properties of the resulting polymers are characterized in detail. Hereby, the polymers feature excellent shape-memory behavior with fixity and recovery rates above 90%. This study shows that the thiol-ene cross-linker can function as both, the stable and the switchable structural moiety rendering the usage of a covalent cross-linker unnecessary. This partial reversibility can also be proven by temperature-depending Raman spectroscopy.     

化学改性乙烯-乙酸乙烯共聚物(EVA)的形状记忆性能研究(Ⅰ)--拉伸比和乙酸乙烯(VA)含量对其形状记忆性能的影响

以过氧化二异丙苯(DCP)为引发剂对乙烯一乙酸乙烯共聚物(EVA)进行化学交联改性，制备具有形状记忆性能的EVA，通过对形状记忆性能和凝胶含量的测定等重点探讨了拉伸比和乙酸乙烯(VA)含量对其形状记忆性能的影响。结果表明，不同VA含量的EVA都存在一最佳拉伸比，在这一拉伸比下其形状记忆性能使各项参数达最大值；VA含量对未交联或交联度小的EVA的形状回复率影响很大，随着VA含量增加，形状回复率增大；VA含量对交联度大的已形成完善网络结构EVA的形状回复率的影响并不明显，形状固定率略降低。     

In situ evaluation of structural changes in poly(ester-urethanes) during shape-memory cycles

The relationship between shape-memory behavior and structure was studied using three series of poly(ester-urethanes) with varying amounts of hard segment. The materials were designed to display a three-phase structure consisting of a disperse phase of crystallites and hard domains embedded in an amorphous matrix based on soft segment. Structure and thermal properties of the resultant materials were investigated using techniques such as modulated differential scanning calorimetry (MDSC), dynamic mechanical analysis (DMA) and small angle X-ray scattering (SAXS). The results revealed morphological changes in the materials during a low temperature shape-memory cycle. To study shape recovery, a deformed specimen was evaluated on a heating stage mounted at the SAXS beamline. Furthermore, to study the effect of temperature during recovery, the specimens were subjected to different thermo-cycles. Under each set of conditions, the phase morphology and composition were investigated. Temporary shape was stored by the metastable structure formed during deformation. The recovery was triggered by the melting of crystallites and hydrogen bonding between hard domains. The recovery process was divided into three stages. Bulk incompatibility and entropic recovery determined the final polyurethane morphology.     

Shape-memory effects of a hydro-epoxy resin system

A novel shape-memory hydro-epoxy resin system was prepared from hydro-epoxy, poly(propylene glycol) diglycidyl ether, and menthane diamine. The relationships between the thermomechanical properties of the system and structural changes were investigated by differential scanning calorimetry, dynamic mechanical analysis, and bending tests. The shape-memory behavior of the hydro-epoxy resin was also characterized by performing a U-type shape-memory test. The results indicate that this novel shape-memory hydro-epoxy resin has good shape-memory performance, its shape recovery ratio (R _r) is almost 100 %, and full recovery is observed after just a few minutes. The glass transition temperature (Tg) of the resin was determined using dynamic mechanical analysis, and the results indicate that Tg decreases from 107 to 65 °C as the poly(propylene glycol) diglycidyl ether content is increased, which means that the Tg of the polymer can be modulated within a certain range by varying the poly(propylene glycol) diglycidyl ether content in order to meet different requirements.     

化学改性乙烯-乙酸乙烯酯共聚物(EVA)的形状记忆性能研究(Ⅱ)--结晶对化学交联EVA形状记忆性能的影响

通过形状记忆性能测试、DSC和DMTA等热分析技术重点，探讨了结晶对EVA形状记忆性能的影响以及形状记忆性能的工艺性和使用性能的影响。结果表明，随着结晶度的增加，形状回复率变化不大。而形状固定率增加；热固性SMP的形状回复性由交联网络的完善程度决定，结晶度对其影响不大；结晶对形状记忆材料的响应温度和模量有较大影响，结晶度高响应温度高，常温模量高。形状固定率由聚合物的力学松弛特别是蠕变决定，结晶度只是其影响因素之一，不是决定性因素。从形状记忆机理出发初步揭示了影响热固性形状记忆高分子材料形状记忆性能的本质因素。     

形状记忆聚合物的发展及应用

介绍形状记忆聚合物的发展历史及最新研究进展，从结构角度分析和探讨了聚合物产生形状记忆效应的原因，并对交联聚烯烃，聚氨酯，聚酯等热致形状记忆聚合物的特性及应用进行了介绍和评价，最后结形状记忆聚合物的发展前景进行了展望。     

High-efficiency shape memory copolymers of polycaprolactone/thermoplastic polyurethane fabricated via in situ ring-opening polymerization

Shape memory blends of polycaprolactone/thermoplastic polyurethane (PCL/TPU) were prepared by in situ ring-opening polymerization (ROP) of ε-caprolactone (CL) and thermoplastic polyurethane (TPU). Fourier infrared spectrometer and ¹H-NMR were used to characterize the chemical structure of PCL/TPU copolymers. The results show that TPU has been involved in the ROP of CL, leading to the formation of copolymers with homogeneous morphologies. Besides, pure PCL and all the blends exhibit an excellent shape fixation ratio of 100%, due to their high crystallinity. When a small amount of TPU is introduced, the crystallinity of PCL decreases, and as a result, the shape recovery ratio of the copolymer is enhanced compared with pure PCL. However, with the increased loading of TPU, the content of PCL as the reversible phase decreases and the storage modulus of the PCL/TPU blend declines, so the driving force for the blends to return from the temporary shape to the initial shape becomes smaller, leading to a decrease in the shape recovery ratio. Notably, when the amount of TPU is only 5%, the shape recovery ratio of the blend could reach 83.3%, which is 26% higher than that of pure PCL, and meanwhile, the tensile strength of the blend decreases slightly. This study provides a new strategy for the design of shape-memory materials with high shape-memory properties.     

Preparation and Properties of Biodegradable Shape Memory Polylactic Acid/Poly(ε-caprolactone) Blends under Volume Elongational Deformation

In this work, a novel eccentric rotor mixer (ERM), which can generate circulating volume elongational deformation, is employed to prepare biodegradable polylactic acid (PLA)/poly(ε-caprolactone) (PCL) thermo-responsive shape-memory blends without a compatibilizer. The results of scanning electron microscopy (SEM) show that the ERM has more efficient dispersion and compatibilization for blends than conventional Banbury mixers, which is beneficial for shape-memory performance. The results of Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) also confirm the consequences. Then, morphological and mechanical properties and shape memory behaviors of the blends are investigated in detail. Co-continuous morphology is found on EF-PLA50. The blends exhibit remarkable shape-memory performance. The bending shape fixing ratio and recovery ratio of the blends are more than 94% and are still more than 90% after five shape memory cycles. With the increase of PLA content, the shape fixing ratio of blends decreases, while the shape recovery ratio increases and the shape recovery time becomes shorter. All the blends show good mechanical properties.     

某些形状记忆热收缩材料的研究进展

综述了交联聚乙烯、(乙烯/乙酸乙烯酯)共聚物、(乙烯/丙烯酸乙酯)共聚物、含氟聚合物、反式1,4-聚异戊二烯等具有形状记忆功能的热收缩材料的研究现状,分析了其形状记忆机理,介绍了这些热收缩材料在包装材料、电线电缆、电子器件和医疗器材等领域的应用。     

Toughening PVC with Biocompatible PCL Softeners for Supreme Mechanical Properties,Morphology, Shape Memory Effects,and FFF Printability

In this article, a first of its kind blend of polyvinyl chloride (PVC) and biocompatible polycaprolactone (PCL) is introduced by melt mixing and then 3D printed successfully via Fused Filament Fabrication (FFF). Experimental tests are carried out on PCL-PVC blends to assess thermo-mechanical behaviors, morphology, fracture toughness, shape-memory effects and printability. Macro and microscopic tests reveal that PVC-PCL compounds are miscible due to high molecular compatibility and strong interaction. This causes extraordinary mechanical properties specially for PVC-10 wt% PCL. In addition to the desired tensile strength (45 MPa), this material has a completely rubbery behavior at ambient temperature, and its total elongation is more than 81%. In addition, due to the high formability of PVC-PCL at ambient temperature, it has capability of being programed via different shape-memory protocols. Programming tests show that PVC-PCL blends have an excellent shape-memory effect and result in 100% shape recovery. SEM results prove a high improvement of PVC printability with the addition of 10 wt% PCL. Toughened PVC by PCL is herein added to the materials library of FFF 3D printers and expected to revolutionize applications of PVC compounds in the field of biomedical 3D and 4D printing due to its appropriate thermo-mechanical properties, supreme printability, and excellent biocompatibility.