以聚α,α-二甲基-β-丙内酯为硬段的三嵌段共聚物的合成与性质

合成了以聚α,α-二甲基-β-丙内酯(PPVL)为硬段,聚己二酸1,2-丙二醇酯(PPA)、聚丁二烯(PBD)及氢化聚丁二烯(HPBD)为软段的ABA型嵌段共聚物及以聚α-甲基苯乙烯(PαMS)和PPVL为硬段,PBD为软段的ABC型嵌段共聚物。发现嵌段共聚物中PPVL的1/T_m∝[软段]/[PPVL],软段含量对降低T_m与力学性能的影响均为PPVL-PPA-PPVL>PPVL-HPBD-PPVL>PPVL-PBD-PPVL,符合软硬段相容性下降的趋势;PPVL-PBD-PαMS的力学性能低于PPVL-PBD-PPVL与PαMS-PBD-PαMS,是因结晶的PPVL与无规的PαMS互不相容。     

[-PPO-PDMS-PHS-]n三元多嵌段共聚物的形态结构和性能

利用DMA, TEM和SAXS对以聚苯醚(PPO)为硬段、聚对羟基苯乙烯(PHS)为半硬段和聚二甲基硅氧烷(PDMS)为软段的三元多嵌段共聚物[-PPO-PDMS-PHS-]n以三种嵌段相容相为连续相, PPO与PHS的相容相和PDMS相为两种分散相, 其tan δ随温度变化曲线在-100℃至200℃一直是一很高的平台, 并具有优异的力学性能, 较好地解决了含有机硅类嵌段共聚物强度低的弱点, 同时又保留了嵌段共聚物微相分离的特性。     

PPO-PDMS-PHS_n三元多嵌段共聚物的形态结构和性能

利用DMA,TEM和SAXS对以聚苯醚(PPO)为硬段、聚对羟基苯乙烯(PHS)为半硬段和聚二甲基硅氧烷(PDMS)为软段的三元多嵌段共聚物(?)PPO-PDMS-PHS(?)_n的形态结构和性能进行了研究.结果表明,(?)PPO-PDMS-PHS(?)_n以三种嵌段相容相为连续相,PPO与PHS的相容相和PDMS相为两种分散相,其tanδ随温度变化曲线在-100℃至200℃一直是一很高的平台,并具有优异的力学性能,较好地解决了含有机硅类嵌段共聚物强度低的弱点,同时又保留了嵌段共聚物微相分离的特性.     

聚醚聚氨酯双离子型离聚物的介电性能研究

以4,4＇-二苯基甲烷二异氰酸酯(MDI)、N-甲基二乙醇胺(MDEA)和聚四氢呋喃(PTMD)以2:1:1(mol比)合成聚醚型聚氨酯,MDEA的叔胺基与γ-丙磺内酯反应,制备了不同磺化程度的双离子型离聚物.在不同温度与频率(-150-30℃,20Hz—100KHz)下,测定了其介电性能.结果表明,随离子化程度的提高,ε＇增大,α弛豫介电损耗峰移向低温,说明相分离越趋完善;β弛豫单元的活化能(△Hβ)基本不变;α弛豫单元的活化能(△Hα)依次变小.介电测量结果与动态力学方法研究结果相吻合.     

聚酯聚氨酯嵌段共聚物及其离聚体的研究

以烃基封端的聚酯与4,4'-二苯基甲烷二异氰酸酯及N-甲基二乙醇胺合成了3种不同硬段含量的聚酯聚氨酯嵌段共聚物。然后,与γ-丙磺酸内酯反应,制得不同离子化程度的离聚物。通过对这些聚合物进行红外光谱、应力-应变试验、差示扫描量热(DSC)、动态力学性能和介电温度谱的分析,得出硬段含量和离子化程度对材料微相分离和物理性能的影响规律,并探讨了引起材料微观形态变化的原因。     

嵌段聚氨酯阴离子离聚物的小角X射线散射研究

用小角Ｘ射线散射研究了嵌段聚氨酯阴离子离聚物中不同离子化程度对离子聚集体形态结构的影响．结果表明：离子含量少时，主要以非聚集离子或多重离子对的形式存在；离子含量多时，主要以离子簇的形式存在．聚氨酯离子化后，有利于软、硬段的微相分离．     

磺酸型聚氨酯离聚物的离子导电性能

本文以多种聚醚为软段，二异氰酸酯（ＭＤＩ和ＴＤＩ）为硬段，合成了多嵌段聚醚聚氨酯，以此聚氨酯为基材，与ＮａＨ及１，３－丙碳酸内酯反应，进一步合成了一系列不同离子化程度的阴离子型碳化聚氨酯离聚物，用交流阻抗谱仪测定了样品的阻抗谱，由此计算出样品的离子电导率。研究结果表明其他条件相同时，以聚乙二醇（ＰＥＧ）为软段的样品具有较高的离子电导率；以聚环氧丙烷（ＰＰＯ）为软段的样品次之，以聚四氢呋喃（ＰＴＭＯ）为软段的样品最低，对于离子化程度不同的聚氨酯离聚物以金属离子和烷氧单元之比为０．０５时导电性能最好。阳离子为Ｌｉ＋和Ｎａ＋的样品具有相近的离子电导率。     

磺酸型阴离子聚氨酯离聚物的研究(Ⅰ)——不同离子化程度对性能的影响

合成了不同离子化程度的磺酸型阴离子聚氨酯离聚物,并通过红外光谱、示差扫描量热、动态力学、应力-应变等方法研究了它们的性能,结果表明:离子化程度不同对聚氨酯离聚物的软硬段相容性有较大的影响,引入少量离子,使软硬段相容性提高,引入大量离子时,则又使软硬段相分离程度提高,随着离子化程度的提高,材料的抗张强度、水溶性逐步提高,为控制聚氨酯材料的亲水性及制备水溶性聚氨酯提供了一种新途径。     

聚α-甲基苯乙烯为硬段的三嵌段共聚物的合成与性能

本工作合成了以聚α-甲基苯乙烯(PαMS)为硬段、聚丁二烯(PBD)及氢化聚丁二烯(HPBD)为软段的两种ABA型三嵌段共聚物。研究了其合成方法、结构与性能,虽然这两种三嵌段共聚物软段T_g相近,均在-25℃左右,但由于氢化聚丁二烯的溶度参数很高,与聚α-甲基苯乙烯的相容性大,以致PαMS-HPBD-PαMS的断裂伸长,断裂强度及回弹性和硬段T_g均较之PαMS-PBD-PαMS有明显下降。     

聚四氢呋喃-聚甲基丙烯酸甲酯两嵌段共聚物的结晶行为

报导了系列聚四氢呋喃-聚甲基丙烯酸甲酯结晶-非晶(硬段型)两嵌段共聚物的结晶行为，结果表明，其微相分离和结晶规律与文献上唯一进行过系统研究的同类嵌段共聚物(PEO－b－PS)都有较大的差别；结晶段结晶能力的大小是制约这类体系微相分离和结晶规律的一个重要因素．     

Morphology and Mechanical Properties of Thermoplastic Polyurethanes Containing Polyisobutylene/Poly(tetramethylene oxide) Mixed Segments

We investigated the thermal properties, microphase separated structure and mechanical properties of a series of thermoplastic polyurethanes (TPUs) containing both polyisobutylene (PIB) and poly(tetramethylene oxide) (PTMO) diols in the soft segment (SS). A series of TPUs were prepared with the same weight fraction of the SS but different ratio between PIB and PTMO diols. Molecular weight of the PTMO diol and chemical structure of the hard segment (HS) also varied. Dynamic mechanical analysis (DMA) measurements did not reveal strong microphase separation between PIB and PTMO in the SS. While it has been assumed that incorporating PTMO diol into the SS can enhance the phase mixing between the hard segment (HS) and SS, our results indicated that, in most cases, the degree of microphase separation of TPUs based on mixed diols is slightly higher than that of TPUs based on only PIB diol.     

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.     

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.     

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.     

Synthesis and degradation of nontoxic biodegradable waterborne polyurethanes elastomer with poly(ε-caprolactone) and poly(ethylene glycol) as soft segment

In this study, in order to obtain waterborne polyurethanes (WBPUs) with biocompatibility, biodegradability as well as good mechanical properties, a series of nontoxic cross-linked waterborne polyurethanes were designed and synthesized with isophorone diisocyanate (IPDI), poly(ε-caprolactone) (PCL), poly(ethylene glycol) (PEG), 1,4-butandiol (BDO) and l-lysine without any other organic agent involved in the whole synthetic process. The bulk structures and properties were characterized by DSC, IR and Instron, mainly focused on the effect of amount of PEG. Their corresponding biodegradability was examined with Lipase AK. The result showed that the prepared waterborne polyurethanes had very good tensile properties, allowing them to be well used as biomaterials. And the change of tensile properties with increasing of amount of PEG in the polymers could be assigned to the change of microphase separation, as indicated by DSC and IR data. A quite good biodegradability was achieved as judged from the change of tensile properties as a function of time. The current work demonstrated a new synthetic approach that can be more promising to prepare both nontoxic and biodegradable polyurethanes for soft tissue engineering applications or drug delivery.     

Morphology of a highly asymmetric double crystallizable poly(epsilon-caprolactone-b-ethylene oxide) block copolymer

The morphology of a highly asymmetric double crystallizable poly(epsilon-caprolactone-b-ethylene oxide) (PCL-b-PEO) block copolymer has been studied with in situ simultaneously small and wide-angle x-ray scattering as well as atomic force microscopy. The molecular masses Mn of the PCL and PEO blocks are 24,000 and 5800, respectively. X-ray scattering and rheological measurements indicate that no microphase separation occurs in the melt. Decreasing the temperature simultaneously triggers off a crystallization of PCL and microphase separation between the PCL and PEO blocks. Coupling and competition between microphase separation and crystallization results in a morphology of PEO spheres surrounded by PCL partially crystallized in lamella. Further decreasing temperature induces the crystallization of PEO spheres, which have a preferred orientation due to the confinements from hard PCL crystalline lamella and from soft amorphous PCL segments in different sides. The final morphology of this highly asymmetric block copolymer is similar to the granular morphology reported for syndiotactic polypropylene and other (co-) polymers. This implies a similar underlying mechanism of coupling and competition of various phase transitions, which is worth further exploration.     

脂肪族水性聚氨酯的动态力学行为研究

合成了一系列脂肪族水性聚氨酯 .考察了软段的组成、软段分子量及DMPA用量对产物动态力学性能的影响作用 .实验结果表明 ,软段的化学结构对水性聚氨酯的相态结构影响很大 .聚醚型水性聚氨酯具有较低的软段玻璃化转变温度 (Tgs) .聚醚型产物的微相分离程度高于聚酯型产物 .当采用聚酯和聚醚二元醇为混合软段时 ,Tgs随软段中聚醚含量的提高而逐渐降低 .提高DMPA用量 ,软段玻璃化转变温度Tgs移向低温区 ,硬段玻璃化转变温度Tgh移向高温区 ,说明体系的微相分离程度加大 .当软段分子量较低时 ,产物为半相容结构 ,只有一个主转变峰 ,软段的玻璃化转变以肩峰的形式出现 ;当软段分子量较高时 ,产物的微相分离程度较高 ,可以分别观察到软段及硬段的玻璃化转变 .总之 ,通过改变软段的种类、组成和分子量以及DMPA用量 ,可以大幅度地改变水性聚氨酯的形态结构 .     

Synthesis and characterization of polydimethylsiloxane polyurea-urethanes and related zwitterionomers

A series of segmented polyurea urethane and polyurea block copolymers based on a hexane diisocyanate (HDI) modified aminopropyl terminated polydimethylsiloxane soft segment was synthesized. The hard segments consisted of 4,4′-methylene diphenylene diisocyanate (MDI) which was chain extended with 1,4-butanediol (BD), N-methyldiethanolamine (MDEA), or ethylene diamine. Zwitterionomers were prepared by quaternizing the tertiary amine of the MDEA extended material with γ-propane sultone. The effect of chemical structure on the extent of phase separation and physical properties was studied using a variety of techniques including thermal analysis, dynamic mechanical spectroscopy, tensile testing, and small-angle x-ray scattering. It was observed that the compatibility between the nonpolar polydimethylsiloxane soft segments and the polar urethane hard segments was improved by inserting HDI linkages into the polydimethylsiloxane soft segments. The aggregation of hard segments was enhanced by increasing hard-segment content or by the introduction of ionic functionality. The tensile strength and modulus of these materials was higher than those of polyurethanes containing soft segments based on polydimethylsiloxane and its derivatives.     

Micro‐phase‐separation behavior of amphiphilic polyurethanes involving poly(ethylene oxide) and poly(tetramethylene oxide)

The temperature dependence of thermal, morphological, and rheological properties of amphiphilic polyurethanes was examined with differential scanning calorimetry (DSC), wide‐angle X‐ray scattering (WAXS), small‐angle X‐ray scattering (SAXS), rheological measurements, and Fourier transform infrared spectroscopy. Multiblock (MPU) and triblock (TPU) polyurethanes were synthesized with two crystallizable segments—poly(ethylene oxide) (PEO) as a hydrophilic block and poly(tetramethylene oxide) (PTMO) as a hydrophobic block. DSC and WAXS measurements demonstrated that the microphase of MPUs in the solid state is dominantly affected by the PEO crystalline phase. However, high‐order peaks were not observed in the SAXS measurements because the crystallization of the PEO segments in MPUs was retarded by poor sequence regularity. The microphase in the melt state was induced by the hydrogen bonding between the N? H group of hexamethylene diisocyanate linkers and the ether oxygen of PEO or PTMO blocks. As the temperature increased, the smaller micro‐phase‐separated domains were merged into the larger domains, and the liquidlike ordering was eventually disrupted because of the weakening hydrogen bonding. However, the fully homogeneous state of an MPU with a molar ratio of 5/5 PEO/PTMO (MPU55) was not confirmed even at much higher temperatures with both SAXS and rheological measurements. However, the SAXS patterns of TPU showed weak but broad second‐order peaks below the melting temperature of the PEO block. Compared with MPU55, the ordering of the TPU crystalline lamellar stacks was enhanced because of the high sequence regularity and the low hydrogen‐bonding density. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2365–2374, 2003     

Effect of Chain Extender on Hydrogen Bond and Microphase Structure of Biodegradable Thermoplastic Polyurethanes

Thermomechanical properties of polyurethanes (PUs) strongly depend on the molecular interactions and microphase structure.In this work,two chain extenders with different ratios,flexile 1,4-butanediol (BDO) and branched trimethylolpropane mono allyl ether (TMPAE),are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes (TPUs).In TPUs,the biodegradable polycaprolactone (PCL,Mn of 2000) is used as soft segment while 1,6-diisocyanatohexane (HDI) and chain extenders are used as hard segment.Fourier transform infrared spectroscopy (FTIR),proton nuclear magnetic resonance spectroscppy (1H-NMR),gel permeation chromatography (GPC),differential scanning calorimetry (DSC),dynamic mechanical analysis (DMA) and mechanical tests were performed to characterize the bulk structure and properties of TPUs.Compared with BDO,the steric bulk of TMPAE is larger.The increment of TMPAE can help to increase the hydrogen bond content,microphase separation,and the elastic modulus ratio (R),which would strongly affect the thermomechanical property of the TPUs.The results of this work verify the importance of the structure of chain extender on the properties of TPUs.It provides valuable information for further understanding the structure-property relationships of these polyurethanes.