Microstructure and properties of polyurethanes derived from castor oil

The goal of this work was the synthesis of novel segmented polyurethanes with a high percentage of components derived from renewable sources. The soft segment was a polyol derived from castor oil and the hard segment structure was varied by means of different chain extenders, petrochemical-based 1,4-butanediol (BD) and corn sugar-based 1,3-propanediol (PD). The synthesis was carried out in bulk and without catalyst via a two-step polymerization varying hard segment ratio. Physico-chemical, mechanical and morphological characterization was performed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), atomic force microscopy (AFM), mechanical testing and termogravimetric analysis (TGA). Properties have been discussed from the viewpoint of hard/soft microdomain phase separation and also the hard segment nature and formed structure. An increase in hard segment content was accompanied by an increase in hard domain order, crystallinity, and stiffness. The hard segment structures, in addition to the elastic nature of soft segment, provide enough physical crosslink sites to impart properties ranging from elastomeric to rigid behaviour with the increase of hard segment content. Polyurethanes synthesized from bio-based chain extender showed a slightly lower crystallinity in the hard segment structure than that synthesized from BD as the chain extender. This lower crystallinity avoids strength concentrations at the soft/crystalline hard segment interface, thus improving the mechanical properties at high hard segment content. The slightly higher thermal stability observed for BD based polyurethanes is related with their more packed structures and crystallinity observed in the hard segment structure.     

Synthesis and properties of poly(ester urethanes) based on cellulose triacetate

Segmented poly(ester urethanes) were synthesized from oligomeric cellulose triacetate diols, poly(caprolactone)diols, and 1,6-hexamethylene diisocyanate. The effects of the molecular mass and structure of soft and hard segments of poly(ester urethanes) on their thermal behavior, mechanical properties, and degradation in aqueous solutions of a phosphate buffer were studied by DSC and IR spectroscopy. The combination of soft segments derived from poly(caprolactone)diols with M = (1.0–3.5) × 10³, hard segments based on depolymerized cellulose triacetate with M = (2–4) × 10³, and 1,6-hexamethylene diisocyanate makes it possible to synthesize poly(ester urethanes) with excellent mechanical characteristics. The degree of crystallinity of these polymers increases with a decrease in the molecular mass of the depolymerized cellulose triacetate block in the hard segment. As the soft segment lengthens, phase separation between domains of soft and hard segments becomes more pronounced. Upon incorporation of poly(ethylene glycol) blocks into the soft segments of poly(ester urethanes), their hydrophobicity is enhanced and biodegradability is accelerated.     

Effect of soft segment length on the thermal behaviors of fluorinated polyurethanes

Differential scanning calorimetry (DSC) and temperature modulated DSC (MDSC) have been applied to investigate the thermal behaviors of fluorinated polyurethanes (FPU), which were obtained using 2,2,3,3-tetrafluoro-1, 4-butanediol as the chain extender and based on various soft segments—polytetramethyl oxides (PTMO) with molecular weights of 650, 1000, 1400 and 2000. An exothermic peak and/or multiple melting endotherms were observed during the heating to melting temperature of soft and hard segments. Attributed to the simultaneous recrystallization and melting processes during heating, these features have been confirmed via MDSC, where an endotherm and an exotherm were noted in reversing and non-reversing components of the heat flow. Separating the non-reversing components from the reversing curves, the dependencies of polyurethane morphology on the length of the soft segment could be clarified using MDSC analysis. Soft segment lengthening significantly influences the morphology of soft segment domains in FPUs. The phase separation and crystallinity of the soft segment increased with its length. However, soft segment length exerted a minor influence on the dissociation temperature of the short-range ordered hard segment domain and on the melting temperature of hard segment crystals. Examination of the heats of melting based on the quasi-isothermal MDSC experiments indicated that the crystallinity of hard segment domains declined with increasing soft segment length.     

Structure and properties of segmented poly(urethaneurea)s with relatively short hard‐segment chains

We report the structure and properties of segmented poly(urethaneurea) (SPUU) with relatively short hard‐segment chains. The SPUU samples comprised poly(tetramethylene glycol) prepolymer as a soft segment and 4,4′‐diphenylmethane diisocyanate (MDI) units as a hard segment that were extended with ethylenediamine. To discuss quantitatively the conformation of the soft‐segment chain in the microphase‐separated domain space, we used SPUU samples for which the molecular weights of the hard‐ and soft‐segment chains are well characterized. The effects of the cohesive force in the hard‐segment chains on the structure and properties of SPUU were also studied with samples of different chain lengths of the hard segment, although the window of x_H, the average number of MDI units in a hard‐segment chain, was narrow (2.38 ≤ x_H ≤ 2.77). There were urethane groups in the soft segments and urea groups in the hard segments. Because of a strong cohesive force between the urea groups, we could control the overall cohesive force in the hard‐segment chains by controlling the chain lengths of the hard segment. First of all, microphase separation was found to be better developed in the samples with longer hard‐segment chains because of an increase of the cohesive force. It was also found that the interfacial thickness became thinner. The long spacing for the one‐dimensionally repeating hard‐ and soft‐segment domains could be well correlated with the molecular characteristics when the assumption of Gaussian conformation was employed for the soft‐segment chains. This is unusual for strongly segregated block copolymers and might be characteristic of multiblock copolymers containing rod–coil chains. The tensile moduli and thermal stability temperature, T_H, increased with an increase of the cohesive force, whereas the glass‐transition temperature, the melting temperature, and the degree of crystallinity of the soft‐segment chains decreased. The increase in T_H especially was appreciable, although the variation in the chain length of the hard segment was not profound. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1716–1728, 2000     

具有热致形状记忆功能的热塑性多嵌段聚氨酯

以ＰＣＬ为软段、ＴＤＩ－ＢＤＯ为硬段，采用溶液聚合的方法合成了具有形状记忆功能的线性多嵌段聚氨酯．利用ＤＳＣ、ＤＭＴＡ、ＷＡＸＤ等测试手段对体系的结晶性、微相分离行为进行了研究．结果发现：聚氨酯中硬段的存在对软段的结晶有着很大的影响，当软段序列的平均分子量达到３０００以上时，软段才可以很好地结晶；并且，硬段含量也必须高于一定值才能形成较为完善的物理交联点．符合这些条件的试样能显示很好的形状记忆特征．此外还就拉伸比、多次形变以及组成等对材料的形状回复性能的影响进行了详细的研究．     

Synthesis and characterization of novel h‐HTBN/PEG PU copolymers for tissue engineering: degradation,phase behavior,and mechanical properties

The phase behavior of the as‐prepared polyether polyurethane (PU) elastomers was investigated by dynamic mechanical analysis (DMA), polarized optical microscope (POM), and atomic force microscopy (AFM). This PU copolymers were composed of different compositions of two soft segments, poly(ethylene glycol) (PEG) and hydrolytically modified hydroxyl‐terminated poly(butadiene‐co‐acrylonitrile) (h‐HTBN) oligomers. The microphase separation behavior is confirmed to occur between soft and hard segments as well as soft and soft segments as the h‐HTBN is incorporated into the PU system, depending on soft‐soft and/or soft‐hard microdomain composition, molecular weight (MW) of PEG, and hydrolysis time of HTBN. The driving force for this phase separation is mainly due to the formation of inter‐ and intramolecular hydrogen bonding interaction. The PU‐70, PU‐50 samples with non‐reciprocal composition seem to exhibit larger microphase separation than any other PU ones. The hydrolysis degradation, thermal stability, and mechanical properties of the copolymers were assessed by gravimetry, scanning electron microscope (SEM), thermal gravity analysis (TGA), and tensile test, respectively. The experimental results indicated that the incorporation of h‐HTBN soft segment into PEG as well as low MW of PEG leads to increased thermal and degradable stability based on the intermolecular hydrogen bond interaction. The PU‐70 and PU‐50 copolymers exhibit better mechanical properties such as high flexibility and high ductility because of their larger microphase separation architecture with the hard domains acting as reinforcing fillers and/or physical crosslinking agents dispersed in the soft segment matrix. Copyright © 2009 John Wiley & Sons, Ltd.     

SHAPE MEMORY EFFECT OF PU IONOMERS WITH IONIC GROUPS ON HARD-SEGMENTS

SMPU （shape memory polyurethane） non-ionomers and ionomers, synthesized with poly（c-caprolactone） （PCL）, 4, 4＇-diphenylmethane diisocyanate （MDI）, 1,4-butanediol （BDO）, dimethylolpropionic acid （DMPA） were measured with cyclic tensile test and strain recovery test. The relations between the structure and shape memory effect of these two series were studied with respect to the ionic group content and the effect of neutralization. The resulting data indicate that, with the introduction of asymmetrical extender, the stress at 100% elongation is decreased for PU non-ionomer and ionomer series, especially lowered sharply for non-ionomer series; the fixation ratio of ionomer series is not affected obviously by the ionic group content; the total recovery ratio of ionomer series is decreased greatly. After sufficient relaxation time for samples stretched beforehand, the switching temperature is raised slightly, whereas the recovery ratio measured with strain recovery test method is lowered with increased DMPA content. The characterization with FT-IR, DSC, DMA elucidated that, the ordered hard domain of the two series is disrupted with the introduction of DMPA which causes more hard segments to dissolve in soft phase; ionic groups on hard segment enhance the cohesion between hard segments especially at high ionic group content and significantly facilitate the phase separation compared with the corresponding non-ionomer at moderate ionic group content.     

Gas permeability of cupric ion containing HTPB based polyurethane membranes

For the purpose of oxygen enrichment from air, the gas permeability and selectivity of an ionic polyurethane membrane was under investigation. Membranes of ionic polyurethane were prepared by step-growth polymerization of hydroxyl terminated polybutadiene (HTPB) and 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI). The ionic group was introduced by adding N-methyldiethanolamine (MDEA) as the chain extender of which the tertiary amines were complexed with cupric ions. The effect of hard segment content, polymerization method, peroxide introduction, and the amount of cupric ion on gas permeability were investigated. It was found that the binding of hard segment and the flexibility of soft segments had subtle effects on gas permeability. Membranes of the same composition were synthesized through two different procedures, one- and two-stage polymerization. The former contains large hard segment of cluster aggregation and flexible soft segments had a higher gas permeation rate. When a crosslinker, benzoyl peroxide, was added, the crosslinkage within soft segments hindered cluster formation by hard segment aggregation, the permeability increased. Furthermore, CuCl₂ addition enhanced hard segment aggregation, more hard segments formed cluster aggregates and less dispersed in soft segment region, which also increased permeability. However, excess CuCl₂ addition resulted in CuCl₂ piling up in the soft segment region, which restricted the movement of soft segments and therefore reduced the gas permeability.     

Microphase separation in RIM polyureas as studied by solid-state NMR

The microphase separation (MPS) in polyureas based on methylene diphenyl diisocyanate (MDI) hard segment, diethyltoluenediamine chain extender, and amino-terminated polypropylene glycol soft segment prepared by reaction injection molding (RIM) was studied by advanced solid-state NMR spectroscopy. Incomplete microphase separation leads to the presence of mobilized hard segments dispersed in the soft segment domains as well as immobilized soft segments residing in the hard domains. This is detected by ¹H-NMR spectra recorded under spinning at the magic angle (MAS) as well as two-dimensional wide-line separation (WISE) NMR spectra. The sizes of the various domains as well as the interfaces between them are quantified by spin diffusion measurements. In this way the impact of annealing, method of polymerization, and hard segment content on MPS is studied. Whereas annealing at temperatures up to 170°C results in improving the MPS, major changes are observed after annealing at higher temperatures (190°C), where the system changes from “soft-in-hard” to “hard-in-soft” behavior. The MPS decreases with increasing hard segment content. The highest MPS is observed for solution polymerized samples. The various NMR experiments clearly reveal the nonequilibrium nature of RIM systems. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 693–703, 1998     

Parameters affecting transition temperatures of poly(lactic acid‐co‐polydiols) copolymer‐based polyester urethanes and their shape memory behavior

A series of polyester urethanes (PEUs) comprising poly(lactic acid‐co‐polydiol) copolymers as a soft segment, 4,4′‐diphenylmethane diisocyanate (MDI) and 1,4‐butanediol (BDO) as a hard segment were systematically synthesized. Soft segments, which were block copolymers of L ‐lactide (LA) and polydiols such as poly(ethylene glycol) and poly(trimethylene ether glycol), were prepared via ring opening polymerization. Glass transition temperatures (T_g) of the obtained PEUs were found strongly dependent on properties of copolymer soft segments. By simply changing composition ratio, type and molecular weight of polydiols in the soft segment preparation step, T_g of PEU can be varied in the broad range of 0–57°C. The synthesized PEUs exhibited shape memory behavior at their transition temperatures. PEUs with hard segment ratio higher than 65 mole percent showed good shape recovery. These findings suggested that it is important to manipulate molecular structure of the copolymer soft segment for a desirable transition temperature and design optimal soft to hard segment ratio in PEU for good shape recovery. Copyright © 2011 John Wiley & Sons, Ltd.     

Shape memory fiber spun with segmented polyurethane ionomer

The effect of cationic groups within hard segments on shape memory polyurethane (SMPU) fibers was studied and the cyclic tensile testing was conducted to assess the shape memory effect. Mechanical properties, hard segment crystallization, and dynamic mechanical properties of SMPU ionomer fibers composed of 1,4‐butanediol (BDO), N‐methyldiethanolamine (NMDA), 4,4′‐methylenebis(phenyl isocyanate) (MDI), and poly(butylene adipate)diol (PBA) were investigated using a universal tensile tester, differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The results demonstrate that only 2 wt% NMDA can significantly change the glass transition temperature of the soft segment phase. DSC shows that the ionic group within hard segments can facilitate the crystallization of hard segments in unsteamed SMPU ionomer fibers. But for steamed fiber specimens, this effect is insignificant. Moreover, the ionic groups in hard segments with different hard segment contents (HSC) have different effects. In unsteamed fibers with 64 wt% HSC, 2 wt% NMDA increases the glass transition of soft segments from 63.5 to 70.6°C. However, in fibers with 55 wt% HSC, the glass transition temperature is lowered from 46.7 to 33.5°C. The post‐treatment, high‐pressure steaming is an effective way to remove the internal stress and subsequently improve the dimensional stability of SMPU ionomer fibers. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal analysis of polyurethane elastomers matrix with different chain extender contents for thermal conductive application

Polyurethane elastomers (PUR) based on polypropylene glycol and 4,4′-diphenylmethane diisocyanate were prepared with various monoethylene glycol (mEG) contents. The aim of this study is to find a reliable polymer matrix for composites of improved thermal conductivity and testing fully in order to collect knowledge about its structure. Thermal conductivity was improved from 0.255 to 0.329 W m^?1 K^?1 when increasing chain extender content. This attributed to a high appearance crystalline ordering level when adding high mEG content. Differential scanning calorimetry revealed a low transition temperature of soft segment at the same temperature around ??64 °C, due to constant polyol content. The enthalpy of melting increases with increasing mEG content. This is due to the increasing crystalline phase and hard segment phase separation within the PUR structure. Dynamic mechanical analysis results show the glass transition temperature of soft segment in the same temperature range between ??57 and ??52 °C and intensity peak of tanδ tends to decrease when mEG content was increased. On the other hand, the glass transition temperature of hard segment tends to increase from 10 to 93 °C and has high intensity peak of tanδ with increasing mEG content. Increasing the chain extender content can be enhancing the hard segment length in PUR structure and affecting both soft segment motion and hard segment motion. Increasing hard segment length might be obstructing soft segment motion and influence hard segment motion which is hard to move at low temperatures. Phase separation of soft and hard segment clearly observed using the DMA technique.

     

Poly(chloropropylmethyl-dimethylsiloxane)–polyurethane elastomers: Synthesis and properties of segmented copolymers and related zwitterionomers

A series of polyurethane block copolymers based on hydroxybutyl terminated poly(chloropropylmethyl-dimethylsiloxane) and poly(tetramethylene oxide) soft segments of molecular weights 2100 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) that was chain extended with either 1,4-butanediol (BD) or N-methyldiethanolamine (MDEA). The materials chain extended with MDEA were ionized using 1,3-propane sultone. The weight fraction of the hard segments was in the range 0.30–0.45. The effect of mixed soft segments, chain extenders, and zwitterionization on the extent of phase separation and physical properties was studied by utilizing differential scanning calorimetry and dynamic mechanical, stress-strain, and Fourier Transform Infrared spectroscopy experiments. All of these short segment block copolymers showed nearly complete phase separation. The zwitterionomer materials exhibited ionic aggregation within the hard domains. Although hard segment crystallinity or ionic aggregation did not affect the morphology, hard domain cohesion was important in determining the tensile and viscoelastic properties of these elastomers.     

Synthesis and properties of comb-shaped segmented poly(urethanes) based on 1,2-propanediol derivatives

Comb-shaped segmented poly(urethanes) have been synthesized from ethers via the one-step procedure with the use of glycerol monostearate, D,L-3-octadecyloxy-1,2-propanediol, 3-tert-butoxy-1,2-propanediol, 3-benzyloxy-1,2-propanediol, and 1,2-propanediol as chain extenders. The soft segment of poly(urethanes) was derived from macrodiol (poly(tetramethylene glycol) with M _n = 1000), and 1,6-hexamethylene diisocyanate and 4,4′-cyclohexylmethane diisocyanate were used as diisocyanates. The effect of the structure of side chains located at the hard segments on the formation of hydrogen bonds in comb-shaped poly(urethanes) has been studied by IR spectroscopy. On the basis of DSC measurements, the glass transition temperatures of the soft and hard segments and the temperature and enthalpy of melting of the crystalline phase have been estimated and the microphase separation of segments has been assessed. The mechanical characteristics of the polymers under study have been examined.     

Waterborne polyurethanes and their properties

Anionomer-type waterborne polyurethanes (PUs) were obtained from poly(β-methyl-δ-valerolactone) glycol (PMVL) and isophorone diisocyanate, following a prepolymer mixing process. The soft-hard segment phase separation in response to the variations of composition and structure of PU has been studied from the dynamic mechanical measurements of the emulsion cast films. The structural variation included ionic and hard segment content, molecular weight of NCO-terminated prepolymer, and type and length of the soft segment. It was found that phase separation is more sensitive to the soft segment length, rather than the soft segment content. With only phase separation, the rubbery modulus was significant even with lower hard segment content. Phase separation was much more pronounced with PU from poly(tetramethylene adipate) glycol, rather than from PMVL and poly(caprolactone) © 1996 John Wiley & Sons, Inc.     

不同硬段含量溶液聚合和RIM嵌段聚脲热性质和动态力学性质的研究

用溶液聚合法和RIM制备了软段为胺端基聚环氧丙烷,硬段为4,4′-二苯甲烷二异氰酸酯(含量为30％,50％,70％)经二乙基甲苯二胺扩链的热塑性嵌段聚脲。用动态力学温度谱(DMS)和示差扫描量热计法(DSC)对比研究了这些聚脲的性质。结果表明,溶液聚脲比RIM聚脲的枢分离情况好。DMS和DSC均未观察到聚脲中硬段的玻璃化转变。     

1,5-萘二异氰酸酯与1,4-丁二醇基为基质的多嵌段聚氨酯弹性体的合成与性能

利用 1 ,5_萘二异氰酸酯 (NDI)和 1 ,4_丁二醇 (BDO)为均匀硬质分子单体 ,与不同软质分子单体 (聚醚、聚酯、聚硅氧烷 )缩合制备多嵌段聚氨酯弹性体 ,详细研究了硬嵌段相 (NDI)弹性体的结构与性能间的关系 ,发现随着硬嵌段相长度的增加 ,或者氨基甲酸酯中胺基与聚醚、聚酯、聚硅氧烷中软段氧原子间氢键的减弱 ,都导致微相分离程度的增加 ,造成聚合物熔点和熔化热的升高。硬嵌段相熔化的多峰行为是由于形成了NDI/BDO半微晶区 ,在退火时转变为更加有序的结晶微区 ,当温度高于 1 80℃时 ,由于氢键的断裂 ,NDI/BDO硬嵌段发生分解反应 ,该过程源于不很有序的硬嵌段半结晶微区。当温度高于 2 5 0℃时 ,发生快速的分解。在动态力学行为方面 ,NDI基聚醚弹性体比其它硅氧烷基的弹性体展示了更高的硬嵌段区的稳定性 ,同时 ,在使用温度范围内 ,也显示出最高的储能模量值 ,表明刚性对温度的依赖性 ,以及NDI/BDO硬嵌段中活性填料的显著影响     

Synthesis and characterization of poly(dimethylsiloxane‐urethane) elastomers: Effect of hard segments of polyurethane on morphological and mechanical properties

A series of poly(dimethylsiloxane‐urethane) elastomers based on hexamethylenediisocyanate, toluenediisocyanate, or 4,4′‐methylenediphenyldiisocyanate hard segment and polydimethylsiloxane (PDMS) soft segment were synthesized. In this study, a new type of soft‐segmented PDMS crosslinker was synthesized by hydrosilylation reaction of 2‐allyloxyethanol with polyhydromethylsiloxane, using Karstedt's catalyst. The synthesized soft‐segmented crosslinker was characterized by FT‐IR, ¹H, and ¹³C NMR spectroscopic techniques. The mechanical and thermal properties of elastomers were characterized using tensile testing, thermogravimetric analysis, differential scanning calorimetry (DSC), and dynamical mechanical analysis measurements. The molecular structure of poly(dimethylsiloxane‐urethane) membranes was characterized by ATR‐FTIR spectroscopic techniques. Infrared spectra indicated the formation of urethane/urea aggregates and hydrogen bonding between the hard and soft domains. Better mechanical and thermal properties of the elastomers were observed. The restriction of chain mobility has been shown by the formation of hydrogen bonding in the soft and hard segment domains, resulting in the increase in the glass‐transition temperature of soft segments. DSC analysis indicates the phase separation of the hard and soft domains. The storage modulus (E′) of the elastomers was increasing with increase in the number of urethane connections between the hard and soft segments. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2980–2989, 2006     

A New Molecular Theory of Non‐Linear Viscoelasticity for Vitrifiable (or Crystallizable) Thermoplastic Polyurethane Elastomers

The molecular theory of non‐linear viscoelasticity for vitrifiable thermoplastic polyurethane elastomers (VTPUE) is a refinement and extension of viscoelastic theory of thermoplastic elastomers and polyurethanes to glassy transition, a structural model and a mechanism of vitrification for glassy polymers were proposed. Five kinds of constituent chains with Nagai chain constraint consisting of soft‐domains, hard‐domains, and entanglements are used as the elementary structural and statistical ensemble units for the correlation of molecular and phase‐domain structures to the static and dynamic mechanical behaviors. So the influences of non‐Gaussian in character, the phase separation of domain, the network topology of structure, the affined deformation of constituent chains, and the thermal history are all taken into account in the constituent chains of the theory. Free energies of deformation for the VTPUE segment copolymer were calculated by the statistical mechanics with the probability distribution functions of the sizes for the five kinds of constituent chains. Then the static constitutive equations and modulus of four types of deformation and the dynamic shear viscosity, modulus and loss tangent of VTPUE are derived from the proposed theory. The theory is successful in relating the molecular chain parameters C₁₀₀, C₀₂₀, and C₂₀₀ to the constitutive equations and modulus under large deformations and the micro‐domain structure to the complex shear viscosity and modulus and the loss tangent. The dynamic shear modulus and loss tangent of VTPUE are related to the domain structures through the fraction of hard segments (W_h), the molecular weight of soft segment (M_ns), and the growth dimensional parameters of hard and soft domains (β). Two series of linear VTPUE copolymers (ES and ET) with different fractions(W_h) of hard segments and molecular weight (M_ns) of soft segments were prepared. Their static and dynamic mechanical properties were studied by uni‐axial extension and dynamic analysis tests. Then the constitutive equation at uni‐axial extension and the expressions of shear modulus and loss tangent are verified by these experimental data, and excellent agreement between the theory and experiments is achieved. It is shown, that the proposed theory can predict the viscoelastic behavior of vitrifiable thermoplastic polyurethanes.     

Water vapor permeability of shape memory polyurethane with amorphous reversible phase

Shape memory thermoplastic polyurethanes (TPUs), based on amorphous soft segment from the reaction of hexamethylene diisocyanate and 1,2‐butane diol, and the crystalline hard segment from 4,4′‐methylenediphenyl diisocyanate and 1,6‐hexanediol, were modified by hydrophilic segments, diol‐terminated poly(ethylene oxide) or dimethylol propionic acid (DMPA). Differential scanning calorimetry, dynamic mechanical testing, tensile testing, and the measurement of shape memory effect, water swell, and water vapor permeability were carried out to examine these TPUs. The hydrophilic segment increased the hysterisis in shape memory effect by reducing the crystallinity of the hard segment. The neutralized DMPA unit enhanced the sensitivity of the thermoresponsive water vapor permeability (WVP) by amplifying the increase of WVP at the temperature range above the glass transition temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3009–3017, 2000