Preparation and characterization of polyurea/polyurethane double‐shell microcapsules containing butyl stearate through interfacial polymerization

Double‐shell microcapsules containing butyl stearate were prepared through interfacial polymerization. The outer shell is polyurea formed through polymerization of toluene‐2,4‐diisocyanate (TDI) and diethylene triamine, and the inner shell is polyurethane (PU) formed through polymerization of TDI and polypropylene glycol 2000 (PPG2000). Styrene maleic anhydride copolymer was used as emulsifier. The effects of core to monomer ratio and dosage of PPG2000 on core content and encapsulation efficiency of microcapsules were investigated. The core content has a maximum at core to monomer ratio of 3–4, and the encapsulation efficiency has a maximum value of 95% at core to monomer ratio of 2. The prepared microcapsules were smooth and compact and have an obvious latent heat of 85 J/g. The shell structure of microcapsules was polyurea and PU. The average diameter of the microcapsules was 1–5 μm. The stabilities of the double‐shell microcapsule, such as anti‐ethanol wash and antiheat properties are obviously improved than those of single‐shell microcapsule. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Perfume‐containing polyurea microcapsules with undetectable levels of free isocyanates

Core‐shell polyurea microcapsules with a 40% fragrance load were prepared by interfacial polymerization of guanidine and a technical polyisocyanate prepolymer containing mainly the biuret trimer derived from hexamethylene di‐isocyanate (HDI). Residual free polyisocyanates were still present at a level slightly above 100 mg NCO functional group per kg as determined by liquid chromatography hyphenated with tandem mass spectrometry of HDI and of its biuret trimer. This level was decreased by a factor of about 10 when the polymerization process was allowed to proceed for a longer time and by a factor of about 500 when guanidine or NaOH were added to the microcapsule suspension to act as scavengers. In these cases, polyisocyanate conversion was observed to proceed for about one month when the microcapsules were stored at room temperature before reaching a plateau at a level below 1 mg NCO/kg. Overall, ammonia was the most efficient polyisocyanate scavenger as no residual HDI biuret trimer and only less than 2 μg NCO/kg as HDI were detected at the end of the process, a level which had dropped below the limit of detection of 0.25 μg NCO/kg after about 40 days of aging at room temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of elastomeric polyurea foam

Polymeric foams are ubiquitous in impact mitigation for civilian and military applications; the performance in such loading scenarios can be elucidated through quasi-static and dynamic mechanical testing. The present study reports on the complex microstructure of newly synthesized polyurea foams exhibiting a hierarchical structure consisting of large perforated semi-closed spherical cells with a mean diameter of 370 ± 162 μm surrounded by smaller closed, spherical cells with size distribution of 69 ± 18 μm. The stress–strain curves were used to calculate the basic mechanical properties and to predict the dynamic behavior of the foams. Nonlinear regression and finite element analyses were used to calibrate the Ogden hyperfoam model to explicate the hyperelastic behavior. The performance of the polyurea foam was found to outperform a benchmark foam in nearly all the elastic and energy absorbing properties. For example, one variation of the newly synthesized foam stored nearly doubled the energy of the benchmark foam while being 12% lighter. Low-density polyurea foam was found to decelerate an incoming impact mass with a minimum G-level that was nearly one third lower than the higher density polyurea and benchmark foams. In all, the behavior of the foam is dependent on the parameters of the fabrication process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48839.     

乙二胺四乙酸四钠盐缓释微胶囊的制备与表征

The microcapsules with cores of ethylenediamine tetraacetic acid tetrasodium salt (Na4-EDTA) and walls of polyurea were synthesized via an interfacial polycondensation reaction with 2,4-tolylene diisocyanate as an oil-soluble monomer and diethyl triamine as a water-soluble monomer. Various manufacturing parameters, including the amount of emulsifier, agitation speed, stirring time and ratios of the wall materials to core materials, were altered to optimize process variables during the synthesis of microcap-sules, and the effects of these parameters on the characteristics of the microcapsules were examined. The structure, morphology, mean particle size and size distribution were characterized by optical microscope and scanning electron microscopy (SEM), showing that the mean diameter of optimal microspheres was approximately 6 μm, and microcapsules were spherical. In vitro release of Na4-EDTA from these microcapsules was performed in distilled water. Under the optimal preparation conditions, the Na4-EDTA re-lease profiles were biphasic with a burst release followed by a gradual release phase. After an initial burst, a continuous Na4-EDTA release was up to 5-7 days. The optimal synthesis conditions for the microcapsules with stable, good morphology and good con-trolled-release properties were as follows: emulsifier Span-80 10% (by mass), agitation speed 900 r&;#8226;min－1, stirring time 30 min, and the ratio of the wall materials to core materials 0.15.     

Photochromic performance optimization of polyurethane microcapsules by interfacial polymerization method

Spiropyran photochromic materials have been widely studied in military camouflage, optical data storage, information encryption, and fashion ornaments. The non-photochromism and low endurance of solid spiropyran make the challenges of their application. Photochromic microcapsules with a butyl acetate solution of spiropyran as core and polyurethane as shell are synthesized via interfacial polymerization. The optimized polyurethane photochromic microcapsules are prepared with a Tween 20 concentration of 4 wt%, core–shell ratio of 16:5, and spiropyran concentration of 0.40 wt%. Polyurethane photochromic microcapsules with a mean particle diameter of 0.33 μm are obtained. The morphology shows smooth spheres, and the core–shell structure is observed. Butyl acetate in the microcapsule core does not evaporate at a temperature lower than 218.01°C as the microcapsule shell insulates heat. The polyurethane photochromic microcapsules are mixed with adhesive, thickener, and water into a paste and screen-printed on cotton fabric. The printed fabric shows the ΔE of 17.56, 11.93, and 6.96 after 80s irradiation with the xenon lamp intensity of 102, 68, and 34 mW cm⁻². The light stability of the photochromic fabric is excellent as ΔE decreases about 8.28% after 20 cycles of UV-Vis irradiation.     

Preparation of hemolysate-filled hexamethylene sebacamide microcapsules with controlled diameter

Hemolysate-filled hexamethylene sebacamide microcapsules (nylon-6, 10 membranes) were prepared by interfacial polymerization. Sheet lattice, frame lattice, turbine and marine impellers were tested to control the microcapsule mean diameter and size distribution parameters. Mean diameters ranging from 40 to 200 μm were obtained depending on the impeller type, rotational speed and emulsifier concentration. The size dispersion of microcapsule preparations was best controlled with a frame lattice impeller, achieving standard deviation values less than 40% of the mean diameter. The wire diameter and mesh dimensions of the impeller lattice had little effect on the distribution parameters.     

芳香疗法--精油的保健和治疗作用

概述了芳香疗法的历史和现状,简要介绍了精油的提取方法和治疗功效,根据芳疗用精油的不同用法,论述了它们的作用机理,展望了芳疗用精油的市场前景。     

纺织品用长效释放生物质精油微胶囊

为避免囊壳原料对环境造成危害，选择可降解的乙基纤维素（EC）为壁材，通过溶剂蒸发法制备了精油微胶囊。结果表明，搅拌速率对微胶囊粒径和表面微孔有较大影响，当搅拌速率为1200 r/min，EC和精油质量分别为1 g和1.5 g时，微胶囊中值粒径为70.8 μm，包封率为44.3%。通过湿法涂层工艺将制备的精油微胶囊用于吸湿透气型复合织物的制备。通过SEM表征可知，该方法保留了基底原形貌。30 d的释放后仍具有39.2%的香味保留率，这得益于胶囊化后精油中乙酸芳樟酯质量分数提高了27.09%，使精油的储存期延长。拉伸-涂层织物表面微胶囊分布均匀、黏覆量多，香味数值可高达382。拉伸和未拉伸制备的复合织物均具有600 mm/s以上的透气率，水洗5次保香率在35%以上，摩擦50次后质量保持在96%以上。这种复合材料的制备方法简单，可以有效改善透气性和牢度无法兼具的问题。     

啶虫脒/脲醛树脂微胶囊的制备及表征

以脲醛树脂为载体,采用原位聚合法制备了啶虫脒/脲醛树脂微胶囊,通过正交实验考察了单体摩尔比、乳化时间、酸化时间、固化时间等对微胶囊载药率、包封率的影响,并对微胶囊的形貌、释药性能和贮存性能进行了表征。结果表明,当尿素与甲醛摩尔比1.0∶1.8、乳化时间1 h、酸化时间1.0 h、固化时间2.0 h时,所得啶虫脒/脲醛树脂微胶囊形态光滑,粒径分布均匀,包封率高且具有良好的缓释效果和贮存稳定性。     

Preparation of monosultap-polyurethane microcapsules in an inverse emulsion through interfacial polymerization

In this study, we prepared monosultap microcapsules in an inverse emulsion through interfacial polymerization for the first time. The microcapsules are spherical pellets with intact and smooth shell and have a narrow particle size distribution with an average size of about 2.35 μm. More importantly, our microcapsules have excellent thermal stability with a starting decomposition temperature of 233.1 °C, high encapsulation efficiency of 81.9% as well as long-term slow release of monosultap under different conditions. In addition, the shell of the microcapsules can degrade completely in the natural condition, avoiding the pollution to the environment. It can be believed that our microcapsules will show good service performance if employed in agricultural industry. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48594.     

Preparation and characterization of polyurethane microcapsules containing n‐octadecane with styrene‐maleic anhydride as a surfactant by interfacial polycondensation

A series of polyurethane microcapsules containing a phase change material (PCM) of n‐octadecane was successfully synthesized by an interfacial polymerization in aqueous styrene‐maleic anhydride (SMA) dispersion with diethylene triamine (DETA) as a chain extender reacting with toluene‐2,4‐diisocyanate (TDI). The average diameter of microPCMs is in the range of 5–10 μm under the stirring speed of 3000–4000 rpm. Optical and SEM morphologies of microPCMs had ensured that the shell was regularly fabricated with the influence of SMA. FTIR results confirmed that the shell material was polyurethane and the SMA chains associated on core material reacted with TDI forming a part of shell material. The shell thickness was decreasing in the range of 0.31–0.55 μm with the molar ratio of DETA/TDI from 0.84 to 1.35 and the weight of core material increasing from 40 to 80% (wt %). By controlling the weight ratio of PCM as 40, 50, 60, 70, and 80% in microPCMs, it was found using DSC that the T_m and T_c of microPCMs were in the range of 29.8–31.0^oC and 21.1–22.0°C and an obvious phase change had been achieved nearly the same temperature range of that of PCM. The results from release curves of microPCM samples prepared by 1.4, 1.7, and 2.0 g of SMA indicated the release properties were affected by the amount of the dispersant, which attributed to the emulsion effect and shell polymerization structure. The above results suggest that the shell structure of microPCMs can be controlled and the properties of microPCMs determined by shell will perform proper practical usage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4996–5006, 2006     

Polyurea microcapsules with different structures: Preparation and properties

Polyurea microcapsules were formed by carrying out an interfacial polycondensation reaction in emulsion globules between various diisocyanates and ethylenediamine to investigate the effects of the chemical structure on various characteristics. FTIR showed that very reactive aromatic 2,4‐toulene diisocyanate produced many more hydrogen‐bonded N—H groups than did other aliphatic diisocyanates. All the microcapsules in this study had prominent thermal stabilities from the results of DSC and TG. It was evident that both the molecular weight and the reactivity of diisocyanates determined the mean diameter and particle‐size distribution at the same time. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 894–898, 2000     

低破损率和尺寸可控制备固定化氯化镍的空心聚脲微球

Polyurea microcapsules containing NiCl2 were prepared by interracial polymerization between diisocyanate and water with triethylamine as a catalyst in water-in-oil emulsion system. The influence of preparation conditions such as the dosage and feed mode of the catalyst, concentration of the encapsulated NiCl2, and concentration and structure of diisocyanates on the breakage of the microcapsules have been evaluated. The results show thatbreakage is strongly dependent on the rate of polymerization and stability of initial emulsion. The improved microcapsules with low breakage have been produced under the optimum conditions. Furthermore, the obtained microcapsules capsules immobilizing NiCl2 as a recyclable catalyst is successfully used in benzaldehyde reduction.     

窄粒径分布的液体石蜡相变微胶囊制备及性能表征

目前相变微胶囊的制备普遍采用传统的机械搅拌乳化方法,获得微胶囊的粒径大小难以控制,粒径分布范围较大。本工作采用快速膜乳化技术结合原位聚合法获得窄粒径分布的液体石蜡/密胺树脂相变微胶囊。研究发现,过膜压力和过膜次数对相变微胶囊的粒径大小和分布影响较大,当微孔玻璃膜孔径固定时,调节过膜压力和过膜次数可以控制微胶囊的粒径大小和分布。当使用孔径为10.1 μm的微孔玻璃膜时,采用过膜压力为0.2 MPa、过膜次数为4次时,可以获得粒径分布最窄的液体石蜡相变微胶囊。此时微胶囊的平均粒径为10.84 μm,相对标准偏差仅为0.16,远小于机械搅拌乳化制备的微胶囊的粒径相对标准偏差。且微胶囊表面光滑致密,无明显团聚,具有良好的耐热性能和冷/热循环稳定性,微胶囊包裹率约为80%。此外,快速膜乳化技术的引入大大提高了乳化效率,从而显著提高了微胶囊制备效率,对其他窄粒径分布的低温烷烃相变微胶囊的批量化制备具有重要意义。     

挥发油的超临界流体萃取与分离进展

挥发油是天然产物中一类重要的活性成分。挥发油的选择性萃取与分离具有非常重要的意义。综述了天然产物中挥发油的超临界流体萃取与分离,介绍了单一超临界流体萃取工艺优化,加入夹带剂,超临界流体萃取与精馏、吸附、分子蒸馏、双逆向蒸发等技术联用,及其在挥发油成分选择性萃取与分离中的应用。     

Effects of shell crosslinking on polyurea microcapsules containing a free‐radical initiator

Microencapsulation of a material is often used when a controlled release of a substance is desired. This study examines the effects of crosslinking in polyurea microcapsule shells on stability of microcapsules containing the free‐radical initiator cumene hydroperoxide (CHP). Crosslinking of polyurea shells was varied by using amine monomers containing different amine functionalities, and/or changing the isocyanate/primary amine ratio. Thermogravimetric analysis was performed to determine thermal properties of these microcapsules, and the pot lives of monomer systems containing these microcapsules were measured. Thermal stability is greater with a moderate degree of crosslinking from a trifunctional amine, and decreases when crosslinking is increased through use of higher amine functionality. Stability in monomer media generally increases with increased crosslinking through higher amine functionality, but is less predictable due to crosslinks formed between capsules. Generally, increasing crosslinking through altering the isocyanate to primary amine ratio decreases capsule stability in both dry and monomer storage. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42408.     

千年健挥发油微波辅助提取研究

采用微波辅助溶剂萃取法(MASE)提取千年健挥发油,并利用GC-MS技术对其化学成分进行了分析。最佳提取条件为:石油醚作溶剂,微波功率600 W,提取温度60℃,提取时间25 min,在该条件下提取的挥发油共鉴定出63种成分,主要为芳樟醇(相对质量分数23.411%,下同),7-乙酰基-2-羟基-2-甲基-5-异丙基二环[4.3.0]壬烷(5.222%),4-松油醇(3.971%)。与传统水蒸气蒸馏法(HD)比较发现,MASE法节省时间,得率更高,同时化学组成成分差异不大,是一种完全可以替代HD法提取千年健挥发油的高效、节能的提取技术。     

基于山苍子精油的复配筛选及协同抗菌性能

为解决单一植物精油在抗菌应用时,用量相对较大、气味单一且浓郁刺激、易引起人们感官不适及过敏反应等问题。通过研究13种单一植物精油对大肠杆菌和金黄色葡萄球菌的抑菌效果,以山苍子精油为基调,采用棋盘稀释法、抑菌圈法、感官评价等方法筛选出具有协同抗菌效果的芳香复配精油,并以大肠杆菌为供试菌探究了其抑菌机理。结果表明,当V(山苍子精油) ∶V(肉桂精油)=2∶1时制备的复配精油对大肠杆菌和金黄色葡萄球菌具有优异的协同抗菌性,抑菌圈直径分别为（21.12±0.17）mm和（40.26±0.61）mm,且香气较愉悦、舒适、易接受。与单一山苍子精油和肉桂精油相比,复配精油对大肠杆菌的抑制效果更为明显,且可以破坏菌体细胞膜,影响细胞膜通透性,导致细胞内离子、核酸等成分泄露,使得菌液相对电导率明显增加,细菌细胞内容物泄露程度与单一山苍子精油和肉桂精油相比分别提升140%和20%。     

基于山苍子精油的复配筛选及协同抗菌性能

为解决单一植物精油在抗菌应用时用量相对较大、气味单一且浓郁刺激、易引起人们感官不适及过敏反应等问题。通过研究13种单一植物精油对大肠杆菌和金黄色葡萄球菌的抑菌效果，以山苍子精油为基调，采用棋盘稀释法、抑菌圈法、感官评价法筛选出具有协同抗菌效果的芳香复配精油，并以大肠杆菌为供试菌探究了其抑菌机理。结果表明，当V(山苍子精油)∶V(肉桂精油)=2∶1时制备的复配精油对大肠杆菌和金黄色葡萄球菌具有优异的协同抗菌性，抑菌圈直径分别为（21.12±0.17）和（40.26±0.61）mm，且香气较愉悦、舒适、易接受。与单一山苍子精油和肉桂精油相比，复配精油对大肠杆菌的抑制效果更为明显，且可以破坏菌体细胞膜，影响细胞膜通透性，导致细胞内离子、核酸等成分泄漏，使菌液相对电导率明显增加，细菌细胞内容物泄漏程度与单一山苍子精油和肉桂精油相比分别提升140%和20%。     

Preparation of polyurea microcapsules containing pyrethroid insecticide with hexamethylene diisocyanate isocyanurate

Polyurea microcapsules containing a pyrethroid insecticide were prepared by the reaction between hexamethylene diisocyanate isocyanurate and ethylenediamine in an oil‐in‐water emulsion. This study was performed to establish the operational conditions of preparing microcapsules by interfacial polymerization and to investigate how the operational conditions affected the characteristics of microcapsules such as the morphology, wall thickness, mean diameter, and particle size distribution. Microcapsules prepared in this study were found to be spherical and monocore. The microcapsule yields, ranging from 94 to 98%, were almost equal to the theoretical values. The wall thickness of the microcapsules increased with the diameter of the microcapsules and the concentration of hexamethylene diisocyanate isocyanurate. In comparison with the results for microcapsules prepared with a mixture of hexamethylene diisocyanate uretidione and isocyanurate, the diameters and wall thickness of the microcapsules were found to be larger. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008