碳纳米管/聚氨酯杂化膜的原位聚合构建及气体渗透性能

采用H2SO4/HNO3混酸处理得到不同氧化程度的多壁碳纳米管(MWCNT-COOH),再通过与4,4′-二苯基甲烷二异氰酸酯(MDI)、1,4-丁二醇(BDO)的预聚和扩链反应构建碳纳米管/聚氨酯(MWCNT-COOH/PU)杂化膜。利用傅里叶红外光谱(FTIR)、拉曼光谱(Raman)和透射电子显微镜(TEM)等分析表征多壁碳纳米管结构;探讨了多壁碳纳米管氧化程度和填充量对MWCNTCOOH/PU杂化膜的形貌和CO2、N2渗透性能的影响。结果表明,混酸处理后的多壁碳纳米管带有一定的含氧基团,并随氧化程度的提高,多壁碳纳米管的拉曼光谱G峰和D峰的强度之比(ID/IG)有所增大;氧化程度对多壁碳纳米管在溶剂和杂化膜中的分散性有较大影响,氧化程度越高,分散性越好;杂化膜的CO2、N2渗透性及CO2/N2渗透选择性随多壁碳纳米管氧化程度的增加有所增大,而随多壁碳纳米管填充量的增加表现出先增大后减小的趋势,当氧化程度较高的多壁碳纳米管(H-MWCNT-COOH)填充量为1.0wt%时,H-MWCNT-COOH/PU杂化膜的CO2渗透系数为67.8 Barrer,CO2/N2渗透选择性可达45,表明适量填充MWCNT-COOH能显著提高MWCNT/PU杂化膜的CO2渗透性及CO2/N2的渗透选择性。     

萘酰亚胺类荧光染料及共聚型荧光聚氨酯乳液的合成与性能

首先以4-溴-1,8-萘酐、2-氨基-1,3-丙二醇和甲醇钠为原料, 经亚胺化和取代两步反应合成出4-甲氧基-N-(2-羟基-1-羟甲基乙基)-1, 8-萘酰亚胺(MHHNA)活性荧光染料, 然后将其作为扩链剂通过相反转自乳化法制备出了共聚型荧光聚氨酯(PU) (PU-MHHNA)乳液, 并分别采用核磁共振氢谱(¹H NMR)、核磁共振碳谱(¹³CNMR)、元素分析、傅里叶变换红外(FTIR)光谱、紫外-可见(UV-Vis)吸收光谱、荧光光谱、粒度分析、氙灯老化等方法对所得荧光染料的化学结构、PU乳液及乳胶膜的性能进行了表征. 结果表明, MHHNA和PU-MHHNA的荧光量子产率分别为0.73 和0.92, MHHNA的用量对所得PU乳液的胶体性质没有明显影响. PU-MHHNA的丙酮溶液在UV-Vis 吸收光谱上的最大吸收波长(λ_max)为360.6 nm, 在荧光光谱上的最大激发波长(λ_ex)和最大发射波长(λ_em)分别为362和435 nm. 随着温度的升高, PU-MHHNA的荧光强度逐渐降低. PU-MHHNA乳胶膜的耐光色牢度和耐溶剂色牢度均明显高于共混型荧光聚氨酯(PU/MBNA)乳胶膜.     

离子液体微乳液合成纳米AgCl及AgCl/poly(MMA-co-St)杂化膜性能调控

在以离子液体氯化-1-十二烷基甲基咪唑(C12mimCl)为表面活性剂,甲基丙烯酸甲酯(MMA)与苯乙烯(St)混合物为油相介质的反相微乳液中合成AgCl纳米粒子,进而采用微乳液原位聚合法制备AgCl/poly(MMA-co-St)杂化膜。通过紫外可见光谱和透射电镜分析了微乳液组成(油相介质组成和增容水量ω)对纳米AgCl粒子形貌的影响。结合扫描电镜和苯、环已烷的溶胀实验探讨了微乳液组成对杂化膜性能的调控作用。结果发现,微乳液油相介质中St/MMA体积比增大有利于在微乳液和杂化膜中获得更多纳米AgCl粒子,增加了杂化膜的苯平衡溶胀吸附量(A∞,b)与苯/环已烷的平衡溶胀吸附选择性(αs,b/c)。在St/MMA体积比为1∶3时杂化膜的A∞,b和αs,b/c分别达到330 mg·g-1和19.21;但过多苯乙烯加入油相介质,其苯环中π键会破坏水核中AgCl粒子的稳定性而引起粒子团聚,从而降低了杂化膜的A∞,b和αs,b/c。反相微乳液中合成的纳米AgCl粒子量随ω增大而增多、粒径增大,杂化膜的A∞,b和αs,b/c随ω的增加而增大。但过高的ω导致微乳液中出现AgCl大粒子,从而引起杂化膜的A∞,b和αs,b/c下降。     

Pickering乳液模板法制备有机/无机杂化微胶囊

以亲水性的二氧化硅(SiO2)纳米粒子稳定的水包油Pickering乳液为模板,利用聚氧化丙烯二醇和二苯基甲烷二异氰酸酯预聚物(PPG-TDI)与二乙烯三胺(DETA)在油水界面的聚合反应制备了聚脲(PU)包裹苯乙酸乙酯(EPA)-异佛尔酮二异氰酸酯(IPDI)有机/无机杂化微胶囊.通过控制不同油水比得到不同粒径大小的微胶囊,粒径分布为20~90μm.热重分析表明EPA-IPDI的装载量达到53 wt%.扫描电子显微镜图片可以看出,微胶囊表面光滑,呈规整球形,厚度均一,约2μm.     

超支化聚氨酯阻尼涂层的制备及性能

以甲苯-2,4-二异氰酸酯(TDI)和二乙醇胺(DEOA)为原料, 采用一步法合成了超支化聚氨酯, 并对其改性制备了光固化超支化聚氨酯(UV-HPU)和超支化杂化聚氨酯(HHPU)两种树脂. 用傅里叶红外光谱(FTIR)和核磁共振氢谱(1H NMR)表征了预期产物. 以其为预聚物制备阻尼涂层, 动态力学分析(DMA)研究表明, 这两种涂层都具有高阻尼因子(tanδ≥1.0)、宽阻尼温度范围(tanδ≥0.5, 大于50 ℃)和宽阻尼频率范围(20～160 Hz); 通过基本性能测试和热重分析(TGA)发现杂化涂层聚氨酯较光固化聚氨酯具有更好的机械性能和热稳定性能; 杂化涂层聚氨酯的FTIR分析可知杂化涂层中硅氧烷水解缩合, 提高了交联密度; 杂化材料的断面扫描电镜(SEM)分析表明, 硅氧烷的水解缩合并未形成大颗粒纳米粒子而是形成均相体系.     

PU-St超浓乳液聚合动力学及聚合物性质的研究

采用一步法制备聚氨酯预聚体 ( PU)苯乙烯 ( St)超浓乳液 ,探讨了稳定的超浓乳液的 NCO/OH和 St/PU最佳比例范围。研究了乳化剂和引发剂浓度对超浓乳液聚合的稳定性及聚合动力学的影响 ,并制得了用 PU改性的聚苯乙烯 ( PS)粉状树脂。测定了乳胶粒子大小、粒径分布、分子量和聚合物膜的动态力学性质。发现乳胶粒子大小及其单分散性随聚合转化率的增加而增加 ;与本体聚合比较 ,聚合物的分子量有明显增大 ;PU- PS复合聚合物具有优良性能。     

pH响应性聚氨酯薄膜的制备

聚氨酯基水凝胶是一种重要的生物医学材料[1 ] ,文献中已报道了块状聚氨酯水凝胶[2 ,3] 、聚氨酯与聚丙烯酸酯的互穿网络水凝胶[4] 、温度及 pH双敏性聚氨酯基水凝胶[5] 等 ,但有关薄膜状聚氨酯凝胶材料还未见报道。本文合成了 5个端丙烯酸酯基聚氨酯预聚物 ,通过紫外光照射固化 ,得到了具有快速pH响应性的敏感薄膜。端丙烯酸酯基聚氨酯预聚物乳液 (PU)参照 [5 ]方法合成。固定聚乙二醇 (PEG)与 2 ,2 二羟甲基丙酸 (DMPA)摩尔比为 3∶7,先使全部的 1 ,6 六亚甲基二异氰酸酯 (HMDI)与PEG及DMPA反应制得异氰酸酯封端的预聚物 ,将该…     

聚氨酯-丙烯酸酯杂化乳液结构与性能的影响

以聚四氢呋喃醚二醇（PTMG）、异氟尔酮二异氰酸酯（IPDI）、亲水单体二羟甲基丙酸（DMPA）,乙二胺为主要原料,制备了稳定的水性聚氨酯乳液.然后以苯乙烯（St）、丙烯酸丁酯（BA）为单体,过硫酸钾为引发剂,在不外加乳化剂的条件下,运用物理共混、化学复合和化学共聚三种方法对该水性聚氨酯乳液进行改性研究.用FTIR技术对聚氨酯-丙烯酸酯杂化乳液的结构进行了对比与表征;通过粘度测定、粒度分析、力学性能和耐水性能测试、DSC分析,研究了不同改性方法对乳液及其胶膜性能的影响.结果表明,化学共聚的改性方法对原水性聚氨酯的耐水性的改良效果最好,能够得到稳定且综合性能较优的聚氨酯-丙烯酸酯杂化乳液.     

聚吡咯/多壁碳纳米管及其聚氨酯导电复合材料的制备和性能

以羧基化多壁碳纳米管(MWCNTs)做模版剂,采用化学氧化法将吡咯(Py)在羧基化MWCNTs表面聚合制备PPy/MWCNTs导电材料,将其添加到溶剂型聚氨酯(PU)溶液中制备了PPy/MWCNTs/PU导电复合材料,研究了Py用量对PPy/MWCNTs及其PU复合材料性能的影响.研究表明,随Py用量的增加,PPy/MWCNTs的长度不变,管径增大,sp~2和sp~3杂化C含量先提高后减少,N的掺杂梯度降低,PPy/MWCNTs的导电率高于羧基化MWCNTs和PPy.当Py用量为羧基化MWCNTs的20%时,其导电率最大.PPy/MWCNTs中N元素的掺杂程度及其管径变化是引起PPy/MWCNTs/PU复合材料的性能不同的主要原因.增加Py用量,MWCNTs中亲水的羧基因对PPy掺杂而消耗,相同导电材料用量时纳米导电粒子数目相对减少,PPy/MWCNTs/PU复合材料的耐水性能提高,定向应力、储能模量和玻璃化温度降低,导电率先增加后减小.当Py用量为羧基化MWCNTs的15%时,导电率最大.     

苯乙烯在阴离子型聚氨酯纳米水分散液中聚合过程的研究

采用自乳化法制备出阴离子聚氨酯纳米水分散液,以其作为乳化剂使苯乙烯单体在其中进行聚合,制备出不同聚苯乙烯与聚氨酯质量比的阴离子型PS/PU纳米复合物水分散液;对苯乙烯单体的聚合过程进行了研究;采用光子相关谱仪和透射电镜对其微观结构、粒径及其分布进行了测试,结果表明,该方法能够制备出稳定的具有核壳结构的PS/PU纳米复合物水分散液,但当苯乙烯单体浓度增大到一定程度(PS/PU质量比为50∶100)时,粒子不稳定而发生聚集.     

Synthesis of poly(urethane‐imide) using aromatic secondary amine‐blocked polyurethane prepolymer

A set of poly(urethane‐imide)s were prepared using blocked Polyurethane (PU) prepolymer and pyromellitic dianhydride (PMDA). The PU prepolymer was prepared by the reaction of polyether glycol and 2,4‐tolylene diisocyanate, and end capped with N‐methyl aniline. The PU prepolymer was reacted with PMDA until the evolution of carbon dioxide ceased. The effect of tertiary amine catalysts, organo tin catalysts, solvents, and reaction temperature were studied and compared with the poly(urethane‐imide) prepared using phenol‐blocked PU prepolymer. N‐methyl aniline blocked PU prepolymer gave a higher molecular weight poly(urethane‐imide) at a lower reaction temperature in a shorter time. Amine catalysts were found to be more efficient than organo tin catalysts. The reaction was favorable in particular with N‐ethylmorpholine and diazabicyclo(2.2.2)octane (DABCO) as catalysts, and dimethylpropylene urea as a reaction medium. The poly(urethane‐imide)s were characterized by FTIR, GPC, TGA, and DSC analyses. The molecular weight decreased with an increase in reaction temperature. The thermal stability of the PU was found to increase by the introduction of imide component. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4032–4037, 2000     

Determination of Crosslinking and Grafting in Polyurethane-acrylic Hybrid Material and Their Theoretical Calculations

A theoretical method to calculate the mode of polyurethane(PU) prepolymers grafted to polyacrylic(PAC) was presented. Using hydroxyethyl acrylate(HEA) as coupling agent, polyurethane-acrylics(PU-AC) hybrid latexes were prepared with varying HEA level and the reaction of HEA with PU prepolymers at different temperatures, and PU grafted to PAC was experimentally determined. The results show that PU grafted to PAC regularly increased, and the non-grafted and linear free PU regularly decreased with increase in ...     

Thermal,mechanical, and morphological properties of soybean oil-based polyurethane/epoxy resin interpenetrating polymer networks (IPNs)

A series of interpenetrating polymer networks (IPNs) based on epoxy (EP) resin and polyurethane (PU) prepolymer derived from soybean oil-based polyols with different mass ratios were synthesized. The structure, thermal properties, damping properties, tensile properties, and morphology of soybean oil-based PU/EP IPNs were characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), universal test machine, and scanning electron microscopy (SEM). DSC and DMA results show that the glass transition temperature of the soybean oil-based PU/EP IPN decreases with the increase of PU prepolymer contents. Soybean oil-based PU/EP IPNs have better damping properties than that of the pure epoxy resin. The tensile strength and modulus of PU/EP IPNs decrease, while elongation at break increases with the increase of PU prepolymer contents. SEM observations reveal that phase separation appears in PU/EP IPNs with higher PU prepolymer contents.     

Morphology of PU/PMMA hybrid particles from miniemulsion polymerization: Thermodynamic considerations

The morphology of PU/PMMA hybrid particles prepared by miniemulsion polymerization was predicted through the consideration of their Gibbs free energy changes. Five morphological states of PU/PMMA hybrid particles were proposed and their Gibbs free energy changes were calculated. Before the formation of hybrid particles, the initial state included a monomer mixture of PU prepolymer, MMA, a chain extender, TMP, and an initiator, which was in droplets suspended in water containing SDS. Two assumptions were made. First, the densities of all states were the same. Secondly, secondary nucleation of particles was negligible. Thus the size of initial droplet and final particle was unchanged through miniemulsion polymerization. The interfacial tensions were measured by a pendant drop method and were used for calculation. The preferred morphology of PU/PMMA hybrid particle had the minimum value of ΔG_phase. Different NCO/OH ratios of PU and initiators of MMA were used to study the morphological change of PU/PMMA hybrid particles. When BD was used as the chain extender of PU, the hybrid particles showed the PU‐rich phase as the shell and PMMA‐rich as the core. When incorporating bisphenol A into PU polymer, the homogeneous structure of hybrid particle was preferred. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3359–3369, 2007     

丙烯酸羟乙酯对丙烯酸酯改性水性聚氨酯性能的影响

以异佛尔酮二异氰酸酯、二羟甲基丙酸和聚丙醚二醇等为聚氨酯原料, 丙烯酸丁酯、甲基丙烯酸甲酯、三羟甲基丙烷三丙烯酸酯为丙烯酸酯类单体, 丙烯酸羟乙酯(HEA)为聚氨酯和聚丙烯酸酯间的偶联剂合成了丙烯酸酯改性水性聚氨酯(PU-AC)乳液. 首先建立并验证了一种测定PU接枝率, 即PU与丙烯酸酯发生接枝的部分占PU总数的百分比的方法, 然后探讨了加入HEA后的反应温度和HEA用量对PU接枝率、PU-AC乳胶粒径、胶膜吸水率和交联度等性能的影响. 随着HEA与PU预聚体反应温度和HEA用量的提高, 体系中的最终残余NCO逐渐降低. 当HEA用量低于其加入前体系中残余NCO量时, 增加其用量使PU接枝率和PU-AC乳胶粒径逐渐增加; 当HEA用量大于体系残余的NCO量后继续增加其用量对PU接枝率和PU-AC乳胶粒径的影响不大. 胶膜吸水率随着HEA用量的增加而降低.     

端羟基聚丙烯酸酯改性水性聚氨酯

将丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)通过溶液自由基聚合,用巯基乙醇作为链转移剂调控合成了一定分子量的端羟基聚丙烯酸酯(PA),再与聚氨酯(PU)预聚体反应,在水中分散得到PA-PU-PA三嵌段共聚复合乳液。 采用FTIR和¹HNMR测试技术对共聚物结构进行了表征。 结果表明,随着PU与PA质量比的降低,共聚物中丙烯酸酯含量随之增加;PU软硬链段之间的氢键化作用减弱。 TEM显示,复合乳胶粒子形态均匀规整,并呈现明显的核壳结构。改性后的乳胶膜耐水、耐热性能均随着PU/PA质量比的减小而提高,吸水率由25%降低至5%,最大热失重温度由369 ℃提高至432 ℃。     

Synthesis and characterization of a new biodegradable polyurethanes with good mechanical properties

In the paper, a new biodegradable polyurethane(PU, PU-I) was prepared: the prepolymer was synthesized via bulk ring-opening polymerization with poly(ethylene glycol)(M_n= 600)(PEG600) as an initiator and L-lactide(L-LA), e-caprolactone(CL) as monomers, and the prepolymer was chain-extended with an isocyanate-terminated urethane triblock(macrodiisocyanate) to prepare the PU. The macrodiisocyanate, prepolymer and PUs were characterized by~1H NMR,~(13)C NMR, FT-IR, high resolution mass spectrometry(HR-MS), gel permeation chromatography(GPC), thermo gravimetric analysis(TGA),and differential scanning calorimetry(DSC). The corresponding PU films showed excellent mechanical properties with a tensile strength of 27.5 MPa and an elongation at break of 996%, and also maintained mechanical properties in physiological saline at 37℃ for more than three weeks, which appeared to be more suitable for biomedical applications.     

A novel type of Si-containing poly(urethane-imide)s: synthesis, characterization and electrical properties

A novel type of a Si-containing poly(urethane-imide) (PUI) was prepared by two different methods. In the first method, Si-containing polyurethane (PU) prepolymer having isocyanate end groups was prepared by the reaction of diphenylsilanediol (DSiD) and toluene diisocyanate (TDI). Subsequently the PU prepolymer was reacted with pyromellitic dianhydride (PMDA) or benzophenonetetracarboxylic dianhydride (BTDA) in N-methyl pyrolidone (NMP) to form Si-containing modified polyimide directly. In the second method, PU prepolymer was reacted with diaminodiphenylether (DDE) or diaminodiphenylsulfone (DDS) in order to prepare an amine telechelic PU prepolymer. Finally, the PU prepolymer having diamine end groups was reacted with PMDA or BTDA to form a Si-containing modified polyimide. Cast films prepared by second method were thermally treated at 160 °C to give a series of clear, transparent PUI films. Thermogravimetric analysis indicated that the thermal degradation of PUI starts at 265 °C which is higher than degradation temperature of conventional PU, confirming that the introduction of imide groups improved the thermal stability of PU.To characterize the modified polyimides and their films, TGA, FTIR, SEM and inherent viscosity analyses were carried out. The dielectrical properties were investigated by the frequency-capacitance method. Dielectric constant, dielectric breakdown strength, moisture uptake and solubility properties of the films were also investigated.     

Thermal and viscoelastic properties of polyurethane-imide/clay hybrid coatings

This paper reports the synthesis and characterization of polyurethane (PU)-imide/clay hybrid coatings based on two types of polyester (PE) polyols (PE-1 and PE-2). PE-1 was prepared from neopentyl glycol (NPG), adipic acid (AA) and isophathalic acid (IPA), whereas PE-2 contains NPG, AA, IPA and TMP (trimethylol propane) with the same hydroxyl value 280 as PE-1. Cetyl trimethyl ammonium bromide (CTAB) modified montmorillonite (K10) was used as the organoclay for the synthesis of the hybrid coatings. The organoclay particles (3 wt%) were well-dispersed into the PE matrix by ultrasonication method. Then the isocyanate terminated PU prepolymers were synthesized by the reaction of polyester polyols with hard segments such as 2,4-toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI) in different NCO/OH ratios e.g., 1.6:1, 2:1 and 3:1, respectively. Finally the thermally stable imide rings were incorporated into the PU backbone by complete reaction of excess NCO content present in the PU prepolymer with pyromellitic dianhydride (PMDA). The thermogravimetric analysis (TGA) shows a higher thermal stability for the PU-imide hybrid coatings with respect to the corresponding PU-imide films. A higher NCO/OH ratio has resulted in higher thermal stability. The activation energies of degradation were calculated by the Broido and Coats-Redfern methods, respectively. The dynamic mechanical thermal analysis (DMTA) results show an enhancement in the glass transition temperature value (T_g) for the clay containing hybrid coatings. The surface analysis by angle resolved X-ray photoelectron spectroscopy (AR-XPS) showed an enrichment of the soft segment towards the surface, and an enhancement in the hard segment composition in the hybrid coatings, resulted in phase mixing.     

Preparation and characterization of the bacterial cellulose/polyurethane nanocomposites

New nanocomposites based on bacterial cellulose nanofibers (BCN) and polyurethane (PU) prepolymer were prepared and characterized by SEM, FT-IR, XRD, and TG/DTG analyses. An improvement of the interface reaction between the BCN and the PU prepolymer was obtained by a solvent exchange process. FT-IR results showed the main urethane band at 2,270 cm^?1 to PU prepolymer; however, in nanocomposites new bands appear as disubstituted urea at 1,650 and 1,550 cm^?1. In addition, the observed decrease in the intensity of the hydroxyl band (3,500 cm^?1) suggests an interaction between BCN hydroxyls and NCO-free groups. The nanocomposites presented a non-crystalline character, significant thermal stability (up to 230 °C) and low water absorption when compared to pristine BCN.