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。     

形状记忆聚氨酯

论述了形状记忆树脂的记忆原理,介绍了形状记忆聚氨酯的性能与用途,并指出了目前其性能的不足与今后研究的重点。     

Shape memory polyurethane-based electrospun yarns for thermo-responsive actuation

Electrospun nanofibrous yarns of shape memory polyurethane (SMPU)-based nanofibers were successfully prepared. The electrospun yarns were analyzed to assess the dependence of mechanical and shape memory properties on the yarn twist angle. The yarn with a 60° twist angle has high compactness and density, leading to increased tensile strength, elastic modulus, and strain energy. In addition, this yarn shows a significant improvement in the shape memory recovery stress compared with the non-twisted SMPU nanofibers. Moreover, thermal stimuli allowed for the 60° twisted yarn to lift a load that is 103 times heavier than itself. This yarn had a shape recovery stress of 0.61 MPa and generated a 7.95 mJ recovery energy. The results suggest the electrospun yarns could be used as actuators and sensing devices in the medical and biological fields.     

双重激发聚氨酯形状记忆泡沫制备与性能研究

以聚乙二醇、聚丙交酯-co-己内酯二醇(PCLA)、液化MDI和水为主要原料,制备了具有可双重激发形状记忆性能的聚氨酯泡沫.通过红外光谱、差示扫描量热、形状记忆、质量损失率和拉伸强度测试,研究了形状记忆聚氨酯泡沫(SMP F)的组成、结晶、形状记忆和在水溶液中的降解性能.结果表明:SMP F结晶熔融温度为41～45℃,...     

Modified shape memory epoxy resin composites by blending activity polyurethane

A series of modified shape‐memory epoxy resin composites were prepared by blending activity polyurethane (APU). Fourier transform infrared spectroscopy (FTIR), tensile tests, scanning electron microscope (SEM), dynamic mechanical analysis (DMA), and fold‐deploy shape memory tests were used to characterize the structure, mechanical, morphology, thermodynamics, and shape memory performance of these materials. FTIR results suggest that APU has been introduced into the resin matrix resin. Tensile test results show that the addition of appropriate APU can increase the elongation at break significantly, compared with neat epoxy. SEM results indicate that the fracture mechanism has changed from brittle to ductile, suggesting that the brittleness of the material has been overcome. DMA results show that modified materials have lower glass transition temperature (T_g) and lower cross‐linking density for shape memory function. Furthermore, the fold‐deploy shape memory tests prove that the materials possess excellent shape memory properties. They can be deformed into different shapes and recover their original shapes fully within 2 min at T_g, while they are hardly affected by ninefold‐deploy cycles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

智能型温敏形状记忆高分子材料的研究进展

综述了热致感应型形状记忆高分子材料的工作原理、形成记忆功能的方法及其分类和应用,介绍了热致感应型形状记忆纤维的生产技术和国内外研究发展状况,并对热致感应型形状记忆高分子材料的未来研究发展趋势作以评述。     

形状记忆功能纤维及纺织品

形状记忆功能纺织品的开发是近年来在纺织材料学中研究较热门的新兴技术。介绍了该材料国内外的研究进展,对形状记忆合金类、形状记忆聚合物类和形状记忆水凝胶类功能纺织品进行了概述;并对各种不同类别的形状记忆功能纺织品的形变机理和适用领域进行了详细阐述,最后展望了形状记忆功能纺织品的未来。     

形状记忆聚氨酯及其应用

主要介绍了形状记忆聚氨酯的最新研究进展及其形状记忆效应的机理和结构特点,分析了其在防水透气织物等领域的应用,并对其发展方向做了展望.     

Synthesis of aminophosphonate polyols and polyurethane foams with improved fire retardant properties

Aminophosphonated polyols with flame retardant properties are synthesized by ring opening polymerization using diethyl-N,N-bis(2-hydroxyethyl) aminomethyl phosphonate (Fyrol-6) as initiator. The influence of the catalyst type and its concentration on the polymerization rate are studied. The catalyst system formed by potassium methoxide (MeOK) in DMSO as a solvent presents the highest polymerization rate and allows reducing the polydispersity. The thermal resistance of the synthesized polyols is confirmed by the char residues formation. Finally, PU foams are synthesized containing up to a 50 pph of PFyCs[1:1], preserving good cellular structure up to a 25 pph content and improving the fire resistance by increasing the char residue from 7.79 to 22.13 wt % and decreasing the PHRR and the smoke production according to TGA and cone calorimeter tests, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47780.     

Crosslinked polyurethanes with shape memory properties

A series of shape memory polyurethanes (SMPUs) was prepared from polycaprolactone diol (PCL) 4000, 1,4‐butanediol (BDO), dimethylol propionic acid (DMPA), triethylamine, and 4, 4′‐diphenylmethane diisocyanate (MDI), to which excess MDI or glycerin were added to obtain crosslinked shape memory polyurethanes. Their mechanical, thermomechanical, thermal and shape memory properties were investigated by using differential scanning calorimetry (DSC), Fourier‐transform (FT‐IR) spectroscopy, dynamic mechanical analysis (DMA) and tensile testing. The results showed that crosslinked SMPUs have better thermal and thermomechanical properties than those prepared from linear polyurethanes and display good shape memory effects. Copyright © 2005 Society of Chemical Industry     

形状记忆聚氨酯

论述了形状记忆聚氨酯的理论模型和数学模型,分析了形状记忆聚氨酯的合成条件和制备技术,介绍了形状记忆聚氨酯的性能、用途及其研究现状,并指出了该材料的不足之处,对今后的研究方向提出了建议。     

Fourier transform infrared study of supramolecular polyurethane networks containing pyridine moieties for shape memory materials

Non‐covalent interactions are increasingly used in the molecular self‐assembly of well‐defined structures. In this study, a series of pyridine‐containing polyurethanes (PUPys) were synthesized with diisocyanates and pyridine derivatives. Fourier transform infrared spectroscopy was employed to identify the vibration frequencies and investigate the relationship of shape memory effect (SME) and hydrogen‐bonded supramolecular structure of the PUPys. The results show that a large fraction of strong hydrogen bonds are formed in the urethane group as well as in the pyridine ring. Moreover, the hydrogen bonding in the pyridine ring not only shows a response to a temperature stimulus in the PUPys, but is also responsive to moisture in N,N‐bis(2‐hydroxylethyl)isonicotinamine (BINA)/hexamethylene diisocyanate (HDI)‐based PUPys; the hydrogen bonds in the urethane group have a higher dissociation temperature and show little response to moisture absorption. Accordingly, the PUPys are expected to show thermally induced and moisture‐induced SMEs. Finally, the shape recovery process of films in the shape of flowers induced by temperature and moisture supports the idea that the PUPys could be used as thermally induced shape memory polymers (SMPs), and the BINA/HDI‐based PUPys could be used as moisture‐sensitive SMPs. Copyright © 2009 Society of Chemical Industry     

Fluorinated waterborne shape memory polyurethane urea for potential medical implant application

A series of crosslinked fluorinated waterborne shape memory polyurethane urea (PUU) ionomers were synthesized from polycaprolactone diol, perfluoropolyether (PFPE) diol, dimethylolproionic acid, isophorone diisocyanate, ethylenediamine (EDA), and diethylenetriamine (DETA). The effect of PFPE content in the soft segment and the degree of crosslinking on the molecular structure and the properties of these PUU films was examined and studied. Differential scanning calorimetry showed that the transition temperature for these T_m type shape memory PUU could be fine tuned by PFPE weight percentage and EDA/DETA ratio in the range between 33 and 44°C, covering the range of body temperature. Although incorporating amorphous fluorinated units into semicrystalline soft segment compromised the shape memory performance of PUU with linear structure as expected, the introduction of crosslinking structure using DETA as a trifunctional chain extender could still retain quite high strain recovery rate (above 90%) at 100% stretching deformation. Furthermore, the relationship of these properties as well as thermal stability with hydrogen bonding was also discussed by evaluation of the carbonyl stretching region in Fourier transform infrared spectra. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polyurethanes having shape memory effects

Segmented polyurethanes (PUs) were prepared from polycaprolactone diols (PCLs), 4,4′-diphenylmethane diisocyanate, and 1,4-butanediol, and tested for shape memory effects. Effects of soft segment molecular weight (M_n = 2000, 4000 and 8000), soft segment content (50–90%), and maximum strain (_m = 100, 200, and 600%) on the cyclic tensile properties as well as the dynamic mechanical, and mechanical properties below (25°C) and above (65°C) the shape recovery temperatures were studied. With increasing soft segment contents: i) glassy state modulus increased and rubbery state modulus decreased; ii) hardness increased at room temperature, and decreased at 65°C; iii) recovery strain decreased with PCL 2000, and increased with PCL 8000 based PUs. On the other hand, the increase in soft segment length resulted in: i) increased rubbery state modulus as well as glass state modulus; ii) increased hardness at room and high temperatures; iii) increased recovery strain at high soft segment content. Tensile yielding became clear with increasing soft segment length and content. Strain upon cooling and unloading (_u) and residual strain (_p) increased, and recovery strain (_r) decreased with cycling. Among these, residual strain was most sensitive to the cycling. Most of the cycling effects were confined during the first one or two cycles. These results were interpreted in terms of soft segment-hard segment phase separation and soft segment crystallization.     

Improved oxidative biostability of porous shape memory polymers by substituting triethanolamine for glycerol

While many aromatic polyurethane systems suffer from poor hydrolytic stability, more recently proposed aliphatic systems are oxidatively labile. The use of the renewable monomer glycerol as a more oxidatively resistant moiety for inclusion in shape memory polymers (SMPs) is demonstrated here. Glycerol-containing SMPs and the amino alcohol control compositions are compared, with accelerated degradation testing displaying increased stability (time to complete mass loss) as a result of the inclusion of glycerol without sacrificing the shape memory, thermal transitions, or the ultralow density achieved with the control compositions. Gravimetric analysis in accelerated oxidative solution indicates that the control will undergo complete mass loss by approximately 18 days, while lower concentrations of glycerol will degrade fully by 30 days and higher concentrations will possess approximately 40% mass at the same time. In real-time degradation analysis, high concentrations of glycerol SMPs have 96% mass remaining at 8 months with 88% gel fraction remaining that that time, compared to less than 50% mass for the control samples with 5% gelation. Mechanically, low glycerol-containing SMPs were not robust enough for testing at three months, while high glycerol concentrations displayed increased elastic moduli (133% of virgin materials) and 18% decreased strain to failure. The role of the secondary alcohol, as well as isocyanates, is presented as being a crucial component in controlling degradation; a free secondary alcohol can more rapidly undergo oxidation or dehydration to ultimately yield carboxylic acids, aldehydes, carbon dioxide, and alkenes. Understanding these pathways will improve the utility of medical devices through more precise control of property loss and patient risk management through reduced degradation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47857.     

Polyurethane foams from soyoil‐based polyols

The focus of this work was to synthesize bio‐based polyurethane (PU) foams from soybean oil (SO). Different polyols from SO were produced as follows: soybean oil monoglyceride (SOMG), hydroxylated soybean oil (HSO), and soybean oil methanol polyol (SOMP). The SOMG was a mixture of 90.1% of monoglyceride, 1.3% of diglyceride, and 8.6% of glycerol. The effect of various variables (polyol reactivity, water content curing temperature, type of catalyst, isocyanate, and surfactant) on the foam structure and properties were analyzed. SOMG had the highest reactivity because it was the only polyol‐containing primary hydroxyl (? OH) groups in addition to a secondary ? OH group. PU foams made with SOMG and synthetic polyol contained small uniform cells, whereas the other SO polyols produced foams with a mixture of larger and less uniform cells. The type of isocyanate also had an influence on the morphology, especially on the type of cells produced. The foam structure was found to be affected by the water and catalyst content, which controlled the foam density and the cure rate of the PU polymer. We observed that the glass transition (T_g) increased with the OH value and the type of diisocyanate. Also, we found that the degree of solvent swelling (DS) decreased as T_g increased with crosslink density. These results are consistent with the Twinkling Fractal Theory of T_g. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The role of branching architecture in shape memory semi-IPNs: Shape memory effect and tube model analysis

The impact of branching architecture of one continuous uncrosslinked phase on properties of classic shape memory semi-interpenetrating polymer networks (semi-IPNs) was explored. Crosslinked poly (methyl methacrylate) (PMMA)/star-shaped polyethylene glycol (PEG) (PMMA/SPEG) semi-IPNs and PMMA/linear PEG (PMMA/LPEG) semi-IPNs were synthesized with the same PEG content. Mechanical properties, phase structure, thermal properties, dynamic mechanical properties, and shape memory properties of these two semi-IPNs systems were compared. Due to the better compatibility of SPEG in the PMMA network, which was derived from little crystallization compared with PMMA/LPEG semi-IPNs, PMMA/SPEG semi-IPNs exhibited a combination of large tensile strength and high elongation at break. PMMA/SPEG semi-IPNs, which had little crystallization exhibited superior shape recovery versus PMMA/LPEG semi-IPNs, which had more crystallization. Moreover, the higher the crystallinity in PMMA/PEG semi-IPNs was the worse long-term temporary shape retention. Based on tube model theory, the high shape recovery capacity of PMMA/SPEG semi-IPNs is mainly ascribed to the retraction of free PEG arms, which is entropically favorable and thermally activated due to the fluctuations of the path length. This result is supported by stress relaxation analysis and the influence of long shape fixity time on shape fixity ratio for these two systems.     

热敏形状记忆高分子材料及其应用

介绍了热敏形状记忆高分子材料及其应用。热敏形状记忆高分子材料是通过温度的变化实现形状的记忆与改变,利用其形状记忆功能,热敏形状记忆弹性体可应用在热缩管、油田封隔器、医用外科、保险杠等领域。     

Effect of molecular weight on shape memory behavior in polyurethane films

Understanding the relationship between the number‐average molecular weight (M_n) and the shape memory behavior of polymers is crucial for a complete picture of their thermomechanical properties, and hence for the development of smart materials, and, in particular, in textile technology. We report here on the study of shape memory properties as a function of M_n of polymers. Shape memory polyurethanes (SMPUs) of different M_n were synthesized, with various catalyst contents or molar ratio(r = NCO/OH) in the composition. In particular, two types of SMPU, namely T_m and T_g types according to their switch temperature type, were synthesized to compare the influence of M_n on their shape memory behavior. X‐ray diffraction, differential scanning calorimetry, dynamic mechanical analysis, and shape memory behavior results for the SMPUs are presented. The results indicate that the melting temperature (T_m), the glass transition temperature (T_g), the crystallinity, and the crystallizability of the soft segment in SMPUs are influenced significantly by M_n, before reaching a critical limit around 200 000 g mol^?1. Characterization of the shape memory effect in PU films suggests that the T_m‐type films generally show higher shape fixities than the T_g‐type films. In addition, this shape fixity decreases with increasing M_n in the T_g‐type SMPU, but the shape recovery increases with M_n in both types of SMPU. The shape recovery temperature, in contrast, decreases with M_n as suggested by the result of their thermal strain recovery. It is concluded that a higher molecular weight (M_n > 200 000 g mol^?1) is a prerequisite for SMPUs to exhibit higher shape recovery at a particular temperature. Copyright © 2007 Society of Chemical Industry     

Blocking of soft segments with different chain lengths and its impact on the shape memory property of polyurethane copolymer

The arrangements, whether block or random type, of the soft segments of polyurethane block copolymers prepared with MDI and two kinds of poly(tetramethylene glycol) (PTMG; MW of 1000 or 2000) in various ratios were compared for possible effects on the physical properties of the copolymers. A long soft segment, PTMG‐2000, was superior in all mechanical properties (strain, stress, and modulus) because a long chain length could provide more motional freedom than a short one (PTMG‐1000) could and therefore was helpful in forming strong interchain attractions among hard segments. Inclusion of more PTMG‐2000 led to a lower T_g and a peak shift in infrared spectra. The arrangement of two soft segments in a block‐type copolymer, a key finding in this study, was controlled by separately synthesizing two prepolymers, each with a different chain length, and connecting two prepolymers in a second step. Random‐type copolymers prepared for purposes of comparison were allowed to react with two PTMGs in one step. Two types of copolymers were compared, and the reason for the differences in the shape memory property are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1435–1441, 2007