New type of thermoplastic multiblock elastomers––poly(ester-block-amide)s––based on oligoamide 12 and oligoester prepared from dimerized fatty acid

Multiblock poly(ester-block-amide)s (PEA) elastomers comprising hard blocks of oligoamide and oligoester soft segments were prepared and their structure-property relations were analysed. The polycondensation reaction of oligoesters (prepared from 1,4-butanediol and dimerized fatty acid) with oligolaurolactam (PA12) gave copolymer series with variable blocks content (the soft segments content was varied from 24 to 60 wt.%). PEAs are the phase system composed of crystallised sequences of oligoamide (hard segment phase) as well as oligoesters (soft segment phase). Mixing between the hard and soft phases was studied by thermal and mechanical measurements (DSC, DMTA). These results have indicated on a multiphase structure of investigated materials. The relationship between the observed thermal and tensile properties and the soft/hard segments content indicated on an increase of the phase separation with soft segments content.     

Poly(urea)urethanes based on amorphous quaternizable hard segments and a crystalline polyol derived from castor oil

A set of poly(urea)urethanes (PUU), with different contents of amorphous hard segment and castor oil-derived crystalline polyol as soft segment, was prepared combining bulk and solution polymerizations. It is shown that both the soft segment crystallinity and hard segment glassy nature control the stiffness of the materials and that phase mixing at intermediate hard segment compositions produces softer materials. Upon yielding, PUU developed large plasticity associated to the nature of soft segments. At longer strains, PUU presented strain-induced crystallization related both to soft segments alignment and crystallization, leading to strong and tough materials, especially with high hard segment content compositions. Despite the hydrophobicity of the soft segments, the PUU with 65 wt% hard segment content was dispersable in water after quaternization with acetic acid. The high amount of urea groups in this quaternized PUU makes one think of these types of polymers as promising water soluble environmentally friendly strong adhesives, coatings, or water soluble polymeric electrolites.     

聚乙二醇型聚氨酯软硬段对其相变储热性能的影响

以不同分子量的聚乙二醇(PEG)为软段,MDI-BDO为硬段,采用两步法溶液聚合合成一种具有固-固相变储热性能的聚氨酯材料.通过DSC,WAXD等测试手段对体系的软硬段结晶性,微相分离,相变可逆性及循环热稳定性进行研究,结果表明,聚氨酯中硬段的存在对软段结晶有着很大的影响,当软段分子量达到2000或以上时,软段才具有较大的结晶度和熔融相变焓,且硬段含量必须高于一定值才能形成较为完善的物理交联网络以保证材料在发生相变时维持固体状态.同时符合这两个条件的试样能具有较好的固-固相变储热性能.就软段PEG含量及分子量对材料储热性能的影响进行了研究,通过调节软段含量与分子量得到一系列具有不同相变焓和相变温度的聚氨酯固-固相变储热材料.经测试还发现,该材料具备很好的相变可逆性和循环热稳定性,是一类很有开发前景的相变储热材料.     

Novel urea-siloxane polymers as gelling agents for silicone fluids

A series of polyureas were synthesized from amino terminated polydimethylsiloxane oligomers of different molecular weight and various diisocyanates. These polymers were characterized by nuclear magnetic resonance (NMR), infrared (IR) spectroscopy and size exclusion chromatography (SEC). The formation of hydrogen bonding of the urea segments was investigated by temperature dependent IR-spectroscopy. The gelation behavior in silicone fluids such as dimethylcyclosiloxanes was investigated. The influence of the structure of the hard and the soft segment on the gelation properties was evaluated.     

Functionalization of polyurethanes by incorporation of alkyne side-groups to oligodiols and subsequent thiol–yne post-modification

A versatile and upscalable method for the synthesis of polyurethanes (PUs) bearing pendant functionalities at the hard–soft segment interface from easily accessible commercial oligodiols is described. Reactive alkyne groups were introduced to polytetrahydrofuran (PTHF), poly(ε-caprolactone) (PCL) and polydimethylsiloxane (PDMS) diols by cationic ring-opening polymerization of glycidyl propargyl ether using these oligodiols as macroinitiators. The resulting oligodiols, with alkyne side groups located at both chain ends, were subsequently reacted with 1,4-butanediol and hexamethylene diisocyanate for the synthesis of PUs, containing several pendant alkyne groups between the soft and hard segments. The functionalized PUs based on different soft segments (PTHF, PCL or PDMS) have been further modified via metal-free thiol–yne chemistry. Proper reaction conditions were found for quantitative radical thiol–yne coupling reactions with benzyl mercaptan and thioglycerol.     

Synthesis and properties of polycyanoethylmethylsiloxane polyurea urethane elastomers: A study of segmental compatibility

A series of polyurea urethane block polymers based on either aminopropyl-terminated polycyanoethylmethylsiloxane (PCEMS) soft segments or soft segment blends of PCEMS and polytetramethylene oxide (PTMO) were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) chain-extended with 1,4-butanediol. The hard segment content varied from 11 to 36%, whereas the PTMO weight fraction in the soft segment blends varied from 0.1 to 0.9. The cyanoethyl side group concentration was also varied during the synthesis of the PCEMS oligomer. The morphology and properties of these polymers were studied by differential scanning calorimetry, infrared spectroscopy, dynamic mechanical and tensile testing, and small-angle x-ray scattering. These materials exhibited microphase separation of the hard and soft segments; however, attaching polar cyanoethyl side groups along the apolar siloxane chains promoted phase mixing in comparison with polydimethylsiloxane-based polyurethanes. The increased phase mixing is postulated to lead to improved interfacial adhesion and thus can account for the observed improvement in ultimate tensile properties compared with polydimethylsiloxane-based polyurethanes. Both hard segment content and cyanoethyl concentration are important factors governing the morphological and tensile properties of these polymers.     

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     

聚环氧氯丙烷氨酯阻尼材料的阻尼性能研究

<正> 一般来讲,聚合物材料的阻尼性能来源于分子链运动带来的内摩擦力以及分子间物理键的破坏与再生,分子链运动所产生的阻尼在聚合物的玻璃化转变温度范围内最为有效。因此具有极性较强、体积较大的一CH_2Cl侧基的环氧氯丙烷聚合物应具有优异的阻尼性能,专利文献[1—2]报道过由多羟基(官能度≥2)聚环氧氯丙烷预聚物为原料制得的聚氨酯泡沫具有良好的阻燃性能,作者在聚环氧氯丙烷氨酯阻尼材料方面进行了尝试。     

Positron studies of the temperature-dependence of free volumes in Polydimethylsiloxane/poly(propylene oxide) urethane/urea membranes

Free-volume parameters in polyurethane/urea membranes have been studied by positron annihilation lifetime and Doppler broadening measurements. The bi-soft segment membranes were obtained by varying the ratio of the structural constituents, polypropylene oxide and polydimethylsiloxane (PU/PDMS), with PDMS content from 25 to 75 wt%. The free-volume holes determined by PALS are correlated with gas permeation features. The phase separation of the various soft and hard segments in the membranes is mirrored in both lifetime and Doppler results.     

Control of hard segment size in polyurethane formation

In general, segmented polyurethane elastomers are prepared by reacting an isocyanate-capped polyol prepolymer with a short-chain diol chain extender, yielding an elastomer with hard segments of uniform size. However, the hard segment size will not be uniform if the polyurethane polymer is prepared by forming the hard segment first, followed by soft segment formation. Because the mechanical properties of polyurethane elastomers depend on the relative ratio of the hard to soft segments as well as the effectiveness of the hard segment as a physical crosslinker, the control of the size distribution of the hard segment is a key factor in designing polyurethane elastomers. It was found that reaction conditions can affect the size distribution of hard segments derived from an aliphatic diisocyanate with differential reactivity between the two isocyanate groups. Lower reaction temperatures and simultaneous mixing of all reactants gave the preferred size distribution of hard segments. © 1995 John Wiley & Sons, Inc.     

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     

Spectroscopic linear dichroism FT-IR studies of synthetic spider silk

This work deals with the analysis of the orientation behavior of different segments of synthetic spider silk samples containing hard and soft segments. Two different types of spider silk were examined, one with an aliphatic hard segment (hexamethylene-diisocyanate) and an amorphous soft segment (polytetramethylene oxide) (A40) and the other with an aromatic hard segment (4,4′-methylene bisphenyl diisocyanate) and a semicrystalline soft segment (polyethylene oxide-polypropylene oxide- polyethylene oxide) (A143). In order to observe the orientation behavior of the hard and the soft segments it was necessary to define marker bands. While for both samples the chosen marker bands for the hard segments were the same, the marker bands for the soft segments were different. FT-IR spectra were recorded while strain was applied to the material at the same time. Two parameters, the dichroic ratio R and the order Parameter f were used to evaluate the behavior of these materials under conditions of strain. It was found that sample A143 broke at a strain level of 37,5 %, while sample A40 showed a high dynamic range up to a strain level of 307 %.     

环氧乙烷-四氢呋喃共聚醚基热塑性聚氨酯弹性体氢键体系的定量研究

氢键为热塑性聚氨酯弹性体内的重要键合力特征。该文基于氢键所引起基团的频移,以FTIR为主要的研究手段,并结合通过动态力学性能（DMA）研究所建立的评估硬段与软段之间混溶的定量方程,对所合成的以环氧乙烷－四氢呋喃无规共聚醚、2,4－甲苯二异氰酸酯以及1,4－丁二醇为原料的热塑性聚醚聚氨酯弹性体的氢键体系进行了定量化研究。结果表明,大约有30％的硬段混溶进入炊段相对软段的醚氧产生氢键作用,主要的氢键包括硬段羰基与硬段氨基之间的氢键以及硬段烷氧与硬段氨基之间的氢键,仍发生在硬段岛区内。     

无光敏剂光引发亲水性单体在嵌段聚醚氨酯膜上接枝聚合的研究

<正> 嵌段聚醚氨酯(SPEU)是一类应用广泛的医用高分子材料。用亲水性单体进行表面接枝改性,已有不少研究,接枝聚合方法有铈盐引发、辐射引发以及光敏引发等。 本文研究一种新的接枝方法,不加光敏剂,用紫外光照射,直接引发亲水性单体接枝于SPEU膜上、接枝的单体有丙烯酰胺(AAM)与N,N-二甲基丙烯酰胺(DMAA),从接枝前后膜的性能变化可以证实接枝反应的发生。文中研究了反应条件与单体结构对接枝率的影响,并通过模型化合物,对接枝部位进行了研究。     

Calorimetric and Dielectric Study of the Segmented Biodegradable Poly(ester‐urethane)s Based on Bacterial Poly[(R)‐3‐hydroxybutyrate]

Two series of segmented poly(ester‐urethane)s were synthesized from bacterial poly[(R)‐3‐hydroxybutyrate]‐diol (PHB‐diol), as hard segments, and either poly(ε‐caprolactone)‐diol (PCL‐diol) or poly(butylene adipate)‐diol (PBA‐diol), as soft segments, using 1,6‐hexamethylene diisocyanate as a chain extender. The hard‐segment content varied from 0 to 50 wt.‐%. These materials were characterized using ¹H NMR spectroscopy and GPC. The polymers obtained were investigated calorimetrically and dielectrically. DSC showed that the T_g of either the PCL or PBA soft segments are shifted to higher temperatures with increasing PHB hard‐segment content, revealing that either the PCL or PBA are mixed with small amounts of PHB in the amorphous domains. The results also showed that the crystallization of soft or hard segments was physically constrained by the microstructure of the other crystalline phase, which results in a decrease in the degree of crystallinity of either the soft or hard segments upon increase of the other component. The dielectric spectra of poly(ester‐urethane)s, based on PCL and PHB, showed two primary relaxation processes, designated as α_S and α_H, which correspond to glass–rubber transitions of PCL soft and PHB hard segments, respectively. Whereas in the case of other poly(ester‐urethane)s, derived from PBA and PHB, only one relaxation process was observed, which broadens and shifts to higher temperature with increasing PHB hard‐segment content. It was concluded from these results that our investigated materials exhibit micro‐phase separation of the hard and soft segments in the amorphous domains.     

Synthesis and characterization of multiblock copolyesters containing poly(dimethylsiloxane) in the soft segments

Synthesis and thermal properties of poly(aliphatic/aromatic-ester) copolymers containing additionally poly(dimethylsiloxane) (PDMS) chains in the soft segments are discussed. A two step method of transesterification and polycondensation from the melt was carried out in a presence of magnesium-titanate catalyst. An aliphatic dimer fatty acid was used as a component of the soft segments while poly(butylene terephthalate) (PBT) constituted the hard blocks. Effectiveness of the incorporation of PDMS into polymer chain was confirmed by the Soxhlet extraction and infrared spectroscopy of an excess of 1,4-butane diol destilled off from the polycondensation reaction. Multiblock copolymers showed microphase separation as determined by differential scanning calorimetry. Incorporation of a small amount of PDMS (up to 14.5 wt.-%) into polymer chain containg low concentration of hard segments of PBT lead to decrease in crystallinity of such copolymers. This may indicate that semicrystalline PBT are dissolved in the amorphous matrix of the soft segments.     

软段和硬段结构对交联的嵌段共聚物力学阻尼及相容性的影响

本文研究了链段结构对多嵌段共聚物网的相容性及动态力学阻尼性能的影响。分别以端乙烯基低聚物作为软链段,乙烯类聚合物作为硬链段,制备了一系列具有不同链段结构共聚物网。它们在大于50℃的温度范围,能阻尼机械振动。共聚物网中某些软链段和硬链段成分是半相容的。基于这些配方的许多共聚物网,在需要的温度范围,tanδ>1.75。     

Random thermotropic elastomers. I. Effects of substitution and hard/soft segment lengths on properties

Syntheses of segmented copoly(ether-ester)s with (oxy-2-methyl-1,4-phenyleneoxycarbonyl-1,4-phenylene carbonyl)/(oxy-2-chloro-1,4-phenyleneoxycarbonyl-1,4-phenylene carbonyl) (methyl-/chloro-substituted) hard segments and poly(oxytetramethylene) soft segments, are reported. The methodology consisted of staged addition melt condensation of terephthaloyl chloride, poly(oxytetramethylene)glycol (POTMG; \[ \bar M_n \] = 250, 650, 1000, 2000) and methyl-/chloro-hydroquinone. Lengths of hard and soft segments were varied while the weight ratio of hard to soft segment was maintained constant. Copolymers were characterised for solubility behavior, and by infrared spectroscopy, x-ray diffraction, DSC, and polarizing microscopy. Thermal properties were found to be dependent on length of soft segment as well as on the type of substituent in the mesogenic core. In both methyl- as well as chloro-substituted copoly(ether-ester)s soft segment glass transition temperature (T_gs) was obtained between ?40 and ?50°C. All copoly(ether-ester)s are elastomeric at room temperature (25°C). These polymers exhibit thermotropic liquid crystalline behavior and were easily sheared and aligned in liquid crystalline state. © 1994 John Wiley & Sons, Inc.     

聚酰胺-聚ε-己内酯多嵌段共聚物合成、表征及反应动力学的研究

本文采用双羧基尼龙1010预聚物和双羟基聚δ-己内酯预聚物经熔融缩聚制得了不同嵌段链长度和不同软硬链段含量的尼龙1010-聚δ-己内酯多嵌段共聚物,并通过分子量(VPO)、核磁共振谱(¹HNMR)和热分析法(DSC)对该共聚物进行表征。同时,对尼龙1010和聚δ-已内酯熔融缩聚反应动力学作了研究。结果表明,该反应为二级反应,活化能为ΔΕ=58.2kcal/mol,反应常数K=1.36×10²²·e^-2.93×104/T。     

Effect of soft segment length on properties of fluorinated polyurethanes

The effects of soft segment length on the variations in morphology, surface composition, and hydrophilicity have been studied in fluorinated polyurethanes (FPUs) and correlated with their preliminary blood compatibility as evidenced by in vitro platelet adhesion experiments. The fluorinated polyurethanes were obtained using hexamethylene diisocyanate (HDI) and chain extender of 2,2,3,3-tetrafluoro-1,4-butanediol (TF) as the hard segment as well as various soft segments—polytetramethyl oxides (PTMO) with molecular weights of 650, 1000, 1400, and 2000. The increased phase separation in hard-segment domains with lengthening soft segment was observed by FT-IR, which is believed to result in enhanced strength of hydrogen bonds and good hard-segment order arrangement. Thin-film XRD results indicate at least three lateral distances existing between adjacent hard segments in the crystallized hard segment. Their distribution depends strongly on the length of soft segment. Lengthening soft segment promotes the formation of dense arrangement of crystallized hard segments. Compared with the effect of phase separation, surface composition was found to exert a major influence on the preliminary blood compatibility of fluorinated polyurethanes. Increasing fluorine content by decreasing soft segment length promotes reduction in platelet adhesion and activation on polyurethane surfaces.