Preparation and Properties of Polyurethane Hydrogels Based on Hexamethylene Diisocyanate/Polycaprolactone-Polyethylene Glycol

Hydrogels are considered an optimum material for controlled release drug systems and tissue engineering scaffolds since they are tri-dimensional networks. In this work hexamethylene diisocyanate (HMDI), polycaprolactone (PCL) and polyethylene glycol (PEG) were used to prepare polyurethane prepolymers using diethylene glycol (DEG) as a chain-extender. Then the prepolymer was used to fabricate the HMDI/PCL-PEG/DEG polyurethane hydrogels by free radical polymerization using benzoyl peroxide (BPO) as a cross-linking agent. The influences of the ratio of polyol on the contact angle, swelling ratio, morphology and cytotoxicity in-vitro of the HMDI/PCL-PEG/DEG polyurethane hydrogel were investigated. The biological behavior of the polyurethane hydrogels was analyzed by studying the cell behavior using the standard biological MTT (3–4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) test. The Fourier transform infrared (FTIR) spectra results showed that the polyurethane hydrogels were successfully synthesized. The change of the molar the ratio of the polyhydric alcohols (PEG and PCL) played important roles in the swelling degree, the contact angle and the pore size. The HMDI/PCL-PEG/DEG polyurethane hydrogel (PCL/PEG = 1:3) was hydrophilic with many more large pores while the polyurethane hydrogel with PCL/PEG = 3:1 had a dense structure. The fibroblastic cell proliferation improved with decreasing relative PEG content; however, there were insignificant differences (P > 0.05) on all days of observation of the samples with various PEG contents compared with the negative control group. The MTT assays revealed that the cells were able to grow and proliferate quite quickly in the extracts of the HMDI/PCL-PEG/DEG polyurethane hydrogels as well as the extract of the negative control.     

Influence of Mass Ratio of Polyols on Properties of Polycaprolactone-Polyethylene Glycol/Methylene Diphenyl Diisocyanate/Diethylene Glycol Hydrogels

Polyurethane (PU) hydrogels with good hydrophilicity and biocompatibility have been applied as biomedical materials. A series of polyurethane prepolymers based on methylene diphenyl diisocyanate (MDI), polycaprolactone (PCL) and polyethylene glycol (PEG), using diethylene glycol (DEG) as the chain-extender, were synthesized; then the polyurethane hydrogels were obtained from the prepolymers using benzoyl peroxide (BPO) as a cross-linker by free radical polymerization. The influences of the ratio of polyols (PCL and PEG) on the contact angle, swelling ratio and morphology of the polyurethane hydrogel were investigated. The loading capacity and release behavior of chloramphenicol from the PCL-PEG/MDI/DEG hydrogels with different compositions were also studied. The contact angle and swelling degree results showed that the PCL-PEG/MDI/DEG hydrogel with PCL/PEG mass ratio of 3:1 had higher hydrophilicity than that with PCL/PEG mass ratios of 1:1 and 1:3. All PCL-PEG/MDI/DEG hydrogels showed three dimensional porous structures; however, the pore size increased with increasing PEG content. The chloramphenicol release kinetics from PCL-PEG/MDI/DEG hydrogels indicated Fickian diffusion, and the drug release rate increased with increasing PEG content in the PU hydrogels.     

二醋酸纤维素与聚乙二醇接枝共聚物的制备与表征

二醋酸纤维素与聚乙二醇接枝共聚物的制备与表征;二醋酸纤维素-聚乙二醇;接枝共聚物;己二异氰酸酯;制备;表征     

生漆与二异氰酸酯的反应及漆膜性能

本文用红外光谱（IR）、动态机械热分析（DMTA）、扫描电镜等仪器和物理、化学手段,研究生漆和2,4-甲苯二异氰酸酯（TDI）的反应特性、聚合成膜机理及漆膜性能等。结果表明,在漆酶和TDI共同作用下,生漆／TDI混合物的固化成膜速率比生漆快得多。当生漆与TDI混合后,生漆乳液的连续相中的漆酚迅速与TDI发生加成反应并生成聚氨酯化合物;在漆酶的催化作用下,该化合物的漆酚基上不饱和侧链双键进一步发生氧化聚合;所得的生漆／TDI涂膜具有优良的物理机械性能。     

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     

离子色谱法测定塑胶场地中甲苯二异氰酸酯

研究了离子色谱-紫外检测法测定塑胶场地样品中的甲苯二异氰酸酯,先将甲苯二异氰酸酯(TDI)水解成甲苯二胺,用CS12A作分离柱,6%CH3CN 20 mmol/L Na2SO4 18 mmoL/L H2SO4的混合液作淋洗液,紫外波长设置为212nm。测定了样品中的TDI,该方法与直流安培检测相比基线更平直,有更好的线性及相对标准偏差,方法的相关系数为0.9994,检出限为8.0μg/L,回收率为110%。     

功能化医用聚氨酯弹性体制备及生物医用研究进展※

热塑性聚氨酯(TPU)弹性体因其良好的可加工性、机械性能和生物安全性而被广泛应用于生物医学领域. 绝大部分TPU都由大分子二元醇软段以及异氰酸酯和小分子扩链剂形成的硬段组成, 这两者分别提供基体的弹性与链网络的框架刚性. 小分子扩链剂二元醇/胺和二异氰酸酯的结构设计是构建功能化TPU的主要途径. 研究者根据特定临床应用场景和使用需求, 设计和制备相应的功能化单体, 并开发出相应的医用TPU. 本综述首先介绍了大分子二元醇、二异氰酸酯以及扩链剂的种类以及各自的特点, 对其特有的微相分离结构做了介绍, 并明晰了化学/物理结构与最终性能的关系. 随后, 综述了国内外TPU在生物医学领域的研究进展和应用, 重点阐述了医用TPU在抗菌、抗凝血、耐水解耐氧化、自愈性以及可降解等方面的发展情况. 最后, 通过总结和分析医用TPU及其器械评价的相关标准, 提出了产业化应用的关键问题, 并展望了医用TPU未来的发展方向.     

Pd‐Pt/modified GO as an efficient and selective heterogeneous catalyst for the reduction of nitroaromatic compounds to amino aromatic compounds by the hydrogen source

In this work, different nitroaromatic compounds were successfully reduced to their corresponding aromatic amines with excellent conversion and selectivity in methanol at 50 °C by using Pd‐Pt nanoparticles immobilized on the modified grapheme oxide (m‐GO) and hydrogen as the reducing source. The catalytic efficiency of Pd and Pd‐Pt loading on the modified GO was investigated for the reduction of various nitroaromatic compounds, and the Pd‐Pt/m‐GO system demonstrated the highest conversion and selectivity. The catalyst was characterized by different techniques including FT‐IR, Raman, UV–Vis, XRD, BET, XPS, FESEM, EDS, and TEM. The metal nanoparticles with the size of less than 10 nm were uniformly distributed on the m‐GO. The catalyst could be reused at least five times without losing activity, showing the stability of the catalyst structure. Finally, the efficiency of the prepared catalyst was compared with Pd‐Pt/AC, and Pd‐Pt/GO catalysts.     

Polymer grafting onto polyurethane backbone via Diels–Alder reaction

The aliphatic polyurethane with pendant anthracene moieties (PU‐anthracene) was prepared from polycondensation of anthracen‐9‐yl methyl 3‐hydroxy‐2‐(hydroxymethyl)‐2‐methylpropanoate (anthracene diol), 1 with hexamethylenediisocyanate in the presence of dibutyltindilaurate in CH₂Cl₂ at room temperature for 10 days. Thereafter, the PU‐anthracene (M_n,GPC = 12,900 g/mol, M_w/M_n = 1.87, relative to PS standards) was clicked with a linear α‐furan protected‐maleimide terminated‐poly(methyl methacrylate) (PMMA‐MI) (M_n,GPC = 2500 g/mol, M_w/M_n = 1.33), or ‐poly(ethylene glycol) (PEG‐MI) (M_n,GPC = 550 g/mol, M_w/M_n = 1.09), to result in well‐defined PU‐graft copolymers, PU‐g‐PMMA (M_n,GPC = 23800 g/mol, M_w/M_n = 1.65, relative to PS standards) or PU‐g‐PEG (M_n,GPC = 11,600 g/mol, M_w/M_n = 1.45, relative to PS standards) using Diels–Alder reaction in dioxane/toluene at 105 °C. The Diels–Alder grafting efficiencies were found to be over 93–99% using UV spectroscopy. Moreover, the structural analyses and the thermal transitions of all copolymers were determined via ¹H NMR and DSC, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 521–527     

Effect of molecular shape of diisocyanate units on the microscopic/macroscopic phase separation structure of polyurethanes

Three diisocyanate units having different linearity and planarity on the basis of the arrangement of constituent aromatic rings are used to synthesize three polyurethanes (PUs) and the effects of the molecular structure of the diisocyanate units on phase separated morphologies of PUs have been studied. The linear and planar diisocyanate unit allows good packing of the hard segments in the hard domain by extensive intersegmental hydrogen bonding, and it forms a well ordered, long hard domain. However, the nonlinear and noncoplanar diisocyanate unit shows a lesser degree of hydrogen bonding in the short hard domain. Strong preferential orientation of the rigid/long hard domains inside a macroscopic grain boundary has been observed with the polarizing optical microscope especially for the PU based on the rigid diisocyanate. It was concluded that the molecular structure of the diisocyanate unit in PU plays an important role in determining the interchain interaction, the detailed phase‐separated domain structure, and local domain orientation in each grain boundary. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011