可降解功能化聚氨酯材料的研究进展

综述了近年来国内外可降解聚氨酯材料研究进展,从聚氨酯分子结构出发详细介绍可降解聚氨酯的种类(天然高分子型可降解聚氨酯、植物油型可降解聚氨酯以及结构型生物可降解聚氨酯)、如何提高聚氨酯的降解性以及可降解聚氨酯的降解机理。重点叙述了可降解聚氨酯在医学、肥料等领域的应用前景,并对可生物降解聚氨酯的发展方向进行了展望。     

读解水性聚氨酯胶粘剂的应用发展概要

由于水性聚氨酯胶粘剂的综合性能优越,在各类水性胶粘剂中独树一帜,近年来受到国内外的广泛关注,特别是高性能水性聚氨酯胶粘剂的开发研究已成为热门课题。针对水性聚氨酯的结构性能和应用领域,介绍了水性聚氨酯胶粘剂的特点,阐述了水性聚氨酯胶粘剂的分类,研究了水性聚氨酯胶粘剂的制备与应用,提出了印刷水性聚氨酯胶粘剂在包装印刷业中的应用及发展,指出了水性聚氨酯胶粘剂的发展趋势。     

泡沫铝-聚氨酯复合材料制备及力学性能分析

目的研究泡沫铝相对密度、聚氨酯含量、聚氨酯硬段质量分数(硬段在热塑性聚氨酯弹性体橡胶中所占的质量分数)对泡沫铝-聚氨酯复合材料力学性能的影响。方法自行制备泡沫铝-聚氨酯复合材料,对制备的泡沫铝-聚氨酯样品进行准静态压缩实验。结果通过准静态压缩实验,得出了不同泡沫铝的相对密度、聚氨酯含量、聚氨酯硬段质量分数分别对应的应力应变曲线。当聚氨酯硬段质量分数和聚氨酯含量一定时,泡沫铝相对密度从5.4%提升到6.1%,泡沫铝-聚氨酯屈服强度增加了12.8%,流变应力增加了29.8%。当聚氨酯硬段质量分数和泡沫铝相对密度一定时,聚氨酯含量从9.21 g提升到13.19g,泡沫铝-聚氨酯屈服强度增加了32.6%,流变应力增加了10.9%。当聚氨酯含量和泡沫铝相对密度一定时,聚氨酯硬段质量分数从15%提升到25%,泡沫铝-聚氨酯屈服强度增加了95%,流变应力增加了55.5%。结论不同的泡沫铝相对密度、聚氨酯含量、聚氨酯硬段质量分数与泡沫铝-聚氨酯复合材料的力学性能成正相关的关系,泡沫铝相对密度、聚氨酯含量、聚氨酯硬段质量分数与泡沫铝-聚氨酯复合材料的缓冲吸能特性成正相关的关系。     

水性聚氨酯涂料改性研究新进展

水分散聚氨酯涂料是一种应用广泛的环境友好型涂料,近年来国内外研究者在提高水性聚氨酯涂料性能方面的研究取得一系列新进展。通过植物油改性、多元复合改性等方法提高了水性聚氨酯的耐水、耐热等性能。此外,新型树枝状水性聚氨酯、抗菌型水性聚氨酯等功能性聚氨酯水性涂料的研发,扩大了聚氨酯的应用范围。对该领域的最新研究成果进行了总结,并对未来水性聚氨酯的发展进行了展望。     

阻燃水性聚氨酯研究进展

阻燃水性聚氨酯是水性聚氨酯功能化的重要方向之一,具有较高的实际应用价值。根据阻燃剂在水性聚氨酯中的存在方式,可以将阻燃水性聚氨酯分为共混复配型和反应型两大类。文中主要从聚氨酯硬段阻燃改性与软段阻燃改性两个方面综述了反应型阻燃水性聚氨酯的研究现状,并展望了阻燃水性聚氨酯的发展趋势。     

水性聚氨酯的合成、性能及应用进展

总结并讨论了水性聚氨酯的合成技术,包括单组分和双组分系统,并介绍了水性聚氨酯的几种共聚改性方法;讨论了水性聚氨酯的性能要求,包括稳定性、耐水性及机械性能等;概述了水性聚氨酯的应用;最后介绍了水性聚氨酯的现状、存在问题及前景.     

超支化多元醇对丁羟聚氨酯灌封胶力学性能影响的研究

采用两种超支化多元醇为交联剂制备了丁羟聚氨酯灌封胶。红外测试结果表明:丁羟聚氨酯灌封胶具有聚氨酯的化学结构;力学性能测试结果表明:相同硬段含量下,与以甘油交联的丁羟聚氨酯灌封胶相比,超支化聚氨酯5代交联得到的丁羟聚氨酯灌封胶的拉伸强度提高了约130%,超支化聚醚5代交联得到的丁羟聚氨酯灌封胶的断裂伸长率提高了约97%。     

超支化聚氨酯与线型聚氨酯共混物相容性及力学性能分子模拟

利用分子模拟软件Materials Studio(MS)4.3对超支化聚氨酯与线型聚氨酯共混物的相容性及力学性能进行了分子模拟,包括用MS4.3的Visualizer程序建立模型、Blends程序计算相容性参数、Amorphous Cell程序计算共混物力学性能。模拟得到:决定低代数超支化聚氨酯与线型聚氨酯共混物的相容性和力学性能的主要因素是超支化聚氨酯外端的修饰基团种类,乙酯作为修饰基团好于丁羟聚氨酯。低代数超支化聚氨酯易与短链线型聚氨酯相容。决定高代数超支化聚氨酯与线型聚氨酯共混物的相容性和力学性能的主要因素是超支化聚氨酯的代数,各种修饰基团的高代数超支化聚氨酯与线型聚氨酯的相容性都能得到改善,且力学性能提高。高代数超支化聚氨酯易与长链线型聚氨酯相容。     

水性聚氨酯固化剂的研究进展

介绍了用于合成聚氨酯固化剂的异氰酸酯类型,综述了聚氨酯固化剂亲水性改性方法及封闭型水性聚氨酯固化剂的封闭机理、封闭剂类型,并指出了水性聚氨酯固化剂研究的不足和未来的发展趋势。     

辐射改性聚氨酯及其生物医学应用

γ射线等的电离辐射所引发的化学反应具有显著的特点,聚合物辐射化学的发展为聚氨酯提供了一个新领域。本文评述了射线作用对聚氨酯结构性能的影响,着重介绍了聚氨酯改性的辐射化学方法,其中,主要综述了聚氨酯辐射交联和辐射接枝改性研究进展,最后讨论了介绍了辐射改性在生物医用聚氨酯方面的应用。     

Biostable highly aligned polyurethane fibres for the potential application of small calibre vascular grafting

Synthetic vascular grafting is necessarily when the autografting is not possible in some cases. Conventional polyethylene terephthalate and expanded polytetrafluoroethylene vascular grafts are found to be effective for diameter bigger than 6 mm but not for the diameter smaller than 4 mm due to the compliance mismatch and thrombogenicity. Endothelization on the surface of the graft can reduce the risks of compliance mismatch and thrombogenicity. In order to catalyst the endothelization process, fibrous morphology similar to the extracellular matrix of our body is preferable in the vascular grafts. Apart from that, the biostability of the grafts is also an essential element to be considered as the biodegradation may reduce the efficiency of the grafts. Many polyurethanes have been recognised as biostable materials. Hence, in this study, highly aligned polyurethane fibres are fabricated using a facile dry spinning technique in the view of providing effective sites for endothelization process to occur. These fibres are immersed into the simulated body fluid for as long as 24 weeks before conducting the biostability characterisations. The biostability is assessed in three aspects, physical, mechanical and chemical properties. Results show that the fibres do not have observable or significant deteriorations in all the three aspects mentioned.     

Synthesis,extrusion and rheological behaviour of PU/HA composites for biomedical applications

Biostable polyurethane/hydroxyapatite (PU/HA) composites with potential application as bone replacement materials were synthesized in bulk and processed in a screw extruder. The polyurethanes (PU) were prepared by reacting an aliphatic diisocyanate, 4-methylene-bis-diisocyanate (MDI), with poly-(ε-caprolactone) (PCL) diols and polytetramethylene oxide (PTMO) of different molecular weights, extended with 1, 4-butanediol (BDO). Glass-transition temperatures were measured by differential scanning calorimetry (DSC). The specific PU groups were assessed by total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The effects of polymer chemistry and filler content on the rheological behaviour were studied by oscillatory rheometry. Polymers with larger chain lengths showed higher viscosity and, for identical chain lengths, polyether urethanes seem to have higher viscosities than polyester based urethanes. A lubricating effect was found for composites containing 50% weight of filler, whereas at higher filler contents a solid-like behaviour was measured. Polymer chemistry seems to be affected by ageing but not so by the presence of filler. Ageing is characterized by a decrease in the concentration of hydrogen bonds involving between urethane linkages.     

Polyurethanes as potential substrates for sub-retinal retinal pigment epithelial cell transplantation

Transplantation of cultured retinal pigment epithelial (RPE) cells under the failing macular is a potential treatment for age related macular degeneration. An important step in the development of this procedure is the identification of a suitable membrane on which to grow and transplant the cells. This paper evaluates the potential of using polyurethanes in this application since they possess several of the required properties, such as, flexibility, robustness, biostability and good biocompatiblilty although their hydrophobicity can limit cell adhesion. Three commercially available polyether urethanes (Pellethane, Tecoflex and Zytar) were evaluated in terms of their wettability using dynamic contact angle analysis and their ability to support a monolayer of functioning RPE cells (ARPE-19) . Furthermore Pellethane and Tecoflex were treated with a simple air plasma treatment and analysed as above. In the "as received condition" only a few RPE cells attached to the Pellethane and Tecoflex and remained clumped. RPE cells grew to confluence on the Zytar substrate by 7 days without further surface modification. Air gas plasma treatment of both Pellethane and Tecoflex increased the wettability of the surfaces and this resulted in the growth of a monolayer of well-spread RPE cells on both materials. Morphologically these cells grew with a normal 'cobblestone' phenotype. These results demonstrate the potential of these polyurethanes for this application.     

Effect of block ratio and strain amplitude on thermal,structural, and shape memory properties of segmented polycaprolactone-based polyurethanes

In this work, the effects of changing molecular weight of polyol (2000, 3000, and 4000) and block ratio as well as deformation amplitude on thermal, structural, and shape memory properties of polyester urethanes based on diphenylmethane diisocyanate, polycaprolactone diol, and 1,4-butanediol were investigated. Fourier transform infrared spectroscopy was used to check the accomplishment of the polyurethanes synthesis. Thermal, structural, and shape memory properties of synthesized SMPUs were measured using differential scanning calorimetry, wide angle X-ray diffraction, and tensile cyclic tests, respectively. It was found that as the crystallinity of soft segments increased, the ability of the samples in fixation of temporary shape was higher. On the other hand, the shape recovery was dominated by the hard segment content and there was a minimum critical HSC for the samples to show appropriate shape memory effects.     

形状记忆聚氨酯与可降解生物材料的研究和应用

综述了形状记忆聚氨酯(PUs)的原理和生物材料降解机制,介绍了形状记忆PUs和可降解生物材料的研究现状,并指出可降解形状记忆PUs生物材料的应用前景及今后研究的重点.     

Effect of the long chain extender on the properties of linear and castor oil cross-linked PEG-based polyurethane elastomers

Polyurethane (PU) elastomers were elaborated from polyethylene glycol of high molecular weight (MW = 4,000), 1,6-hexamethylene diisocyanate and polyethylene glycol (PEG₁₅₀₀) (MW = 1,500) as a long linear chain extender and/or castor oil as a cross-linker and were obtained in the form of transparent films. These poly(ether urethanes) elastomers are obtained by replacing the short-chain diol monomers with high molecular weight polyethylene glycols (PEG₁₅₀₀). High molecular weight polyethylene glycol (MW = 4,000 and 1,500, respectively) have greater chain length thus producing networks with lower cross-linking densities and higher average molecular weight between two consecutive cross-links. The PU properties were investigated using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, mechanical analysis and thermogravimetry. The results showed that the prepared polyurethanes (PUs) had very good tensile properties. The stress–strain data show that the PU elastomers obtained using a 60/40% OH_PEG1500/OH_{castor oil} ratio have the best mechanical properties. The thermal degradation of the castor oil cross-linked PU elastomers starts at 280–300 °C, compared to the thermal degradation of linear PUs which begins at 220 °C. During storage at 25 °C, the morphology and mechanical properties of the elastomer films have been observed to change in time.     

Characterization and biocompatibility studies of new degradable poly(urea)urethanes prepared with arginine, glycine or aspartic acid as chain extenders

Polyurethanes are very often used in the cardiovascular field due to their tunable physicochemical properties and acceptable hemocompatibility although they suffer from poor endothelialization. With this in mind, we proposed the synthesis of a family of degradable segmented poly(urea)urethanes (SPUUs) using amino acids (l-arginine, glycine and l-aspartic acid) as chain extenders. These polymers degraded slowly in PBS (pH 7.4) after 24 weeks via a gradual decrease in molecular weight. In contrast, accelerated degradation showed higher mass loss under acidic, alkaline and oxidative media. MTT tests on polyurethanes with l-arginine as chain extenders showed no adverse effect on the metabolism of human umbilical vein endothelial cells (HUVECs) indicating the leachables did not provoke any toxic responses. In addition, SPUUs containing l-arginine promoted higher levels of HUVECs adhesion, spreading and viability after 7 days compared to the commonly used Tecoflex^® polyurethane. The biodegradability and HUVEC proliferation on l-arginine-based SPUUs suggests that they can be used in the design of vascular grafts for tissue engineering.     

Synthesis and characterization of BHETA based new polyurethanes

Recycling of polyethylene terephthalate (PET) by aminolysis breeds environmental benefits. In this work Polyethylene terephthalate in the form of waste fibers were subjected to depolymerization through aminolysis using excess amount of ethanolamine in the presence of sodium acetate, as catalyst. Obtained product, bis (2‐hydroxy ethylene) terephthalamide (BHETA) was in its pure form with sufficiently high yields. The purified product was characterized by FTIR, ¹HNMR and ¹³CNMR spectroscopy as well as melting point determination. Since catalyst and raw materials have low price, synthesis of this material is economical and could be used as diol to synthesis of polyurethanes. In this search, polyurethanes have been synthesized based on BHETA, HDI and polyethylene glycol via prepolymer method. Termogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) were carried out to study thermal stability, thermal transitions, T_m and T_g of synthesized polyurethanes. Effect of BHETA content in the main chain of synthesized polyurethanes on thermal stability of polyurethanes, strength and stiffness has been evaluated. BHETA based polyurethanes show Young's modulus about 300 MPa and elongation at break as 130% due to its aromatic structure.     

Feasibility of metal recovery from soil using DTPA and its biostability

Removal of heavy metals from contaminated soil by chelation can be a valid remediation method. Important properties of the chelating agent used are: strength of the chelation bonding, reusability, and biostability during the remediation operation. This work tested the extraction, recovery, and biostability of diethylenetriaminepentaacetate (DTPA) as a remediation agent for soils contaminated with metals. Reported here are effects of parameters such as DTPA concentration, precipitant type and concentration, and pH relative to extraction and recovery efficiencies of the chelator, as well as workable recovery conditions. The assessment of biostability was determined at different DTPA concentrations, in aqueous and soil slurry systems, and in presence of lead using acclimated and unacclimated activated sludge cultures. The results showed that DTPA was capable of extracting lead from the tested contaminated soils and could be recovered by the use of cationic and anionic precipitants in alkaline pH conditions. It was biostable to some extent especially with unacclimated cultures. Thus, DTPA proved to be a strong and reusable chelating agent for some metals in soils, and it was relatively biostable, which makes it a valid remediation agent for soil metal extraction.     

Effect of polyurethane composition and the fabrication process on scaffold properties

The microdomain structure of polyurethanes (PUR) determines their unique physical properties and makes polyurethanes attractive candidates for various tissue engineering applications. 3D scaffolds based on polyurethanes with different contents of hard segments were fabricated by a salt-leaching/polymer coagulation method. The process parameters were carefully considered, particularly the polymer solution concentration and characteristics of the polyurethane, which are the critical parameters for the control of porosity and pore size distribution. In this study, 3D polyurethane scaffolds were fabricated with interconnected pores and porosity from 64% to 80%. Pore size distribution was evaluated using quantitative image analysis and mercury intrusion porosimetry (MIP). The scaffolds fabricated from polyurethanes with 70 wt.% of hard-domain content were found to have the best compression properties.