Encapsulation of polar phase change materials via multiemulsification and crosslinking method and its application in building

Phase change microcapsules are prepared using chitosan as shell material and aliphatic alcohol/aliphatic acid as core material via multiemulsification and crosslinking method. During the phase change process, the phase change microcapsules store and release heat energy. The enthalpy value of these phase change microcapsules is high enough to be used for application. Suitable phase change temperature can be obtained by changing the core material easily. The resulted microcapsules showed excellent thermal stability. Thermal gravity analysis results showed that the microcapsules remain stable below 200 °C. The microcapsules also exhibited good solvent resistance because of the crosslinking of the shell material chitosan. By integrating the microencapsulated phase change materials (2.5%) into building walls, the inner temperature of model house remained 2 °C higher than that without PCM during the test process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47837.     

The microencapsulation of calcium chloride hexahydrate as a phase‐change material by using the hybrid coupler of organoalkoxysilanes

A novel method of microencapsulation for inorganic salt hydrates as phase‐change material (PCM), which is essential for their broad application, was pursued by combining sol–gel process with interfacial polymerization. Calcium chloride hexahydrate (CCH), chosen as a representative PCM of salt hydrates, was used as a core material, and organoalkoxysilane was applied to provide hybrid properties of mediating the hydrophilic core and hydrophobic shell material. The Fourier transform infrared spectra and SEM images confirmed that the siloxane and polyurea shell material successfully capsulated the CCH core. Fine morphology of microcapsules was further investigated with SEM, and it presented almost‐spherical shape and a well‐defined core–shell structure. Thermogravimetric analysis indicated that microcapsules containing CCH have sufficient thermal stability, which usually degraded in four steps. Differential scanning calorimeter investigation confirmed additionally that the microencapsulated CCH absorbs thermal energy with phase change during the melt process but undergo a severe super cooling phenomenon in the crystallizing process. In addition, the durability test was conducted to evaluate the siloxane polymer and polyurea as a shell material, protecting CCH from leaking. The effect of pH and the ratio of ingredients were studied in terms of encapsulation possibility and performance of core PCM, which include morphology of core–shell particles and essential thermal properties as a PCM. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45821.     

Fragrant finishing of cotton with microcapsules: comparison between printing and impregnation

Microencapsulated fragrance was used to produce a fragrant textile product. Melamine–formaldehyde polymer wall microcapsules with a lavender, rosemary and sage essential oil core were applied to a cotton fabric in two ways, i.e. byscreen printing and impregnation. The samples were dried and cured, and then the differences between them were analysed. The condition and distribution of applied microcapsules were observed by scanning electron microscopy, fragrance evaluation was performed on printed and impregnated samples after they had been washed several times, and their handle properties were investigated. Moreover, the influence of artificial light on the wall of microcapsules was examined, and possible antibacterial activity against Staphylococcus aureus and Escherichia coli was evaluated. The change in colour of all samples as a consequence of the addition of microcapsules to the paste or bath was checked. The results show that both application techniques are appropriate for the effective fragrant but on the other hand ineffective antibacterial finishing of cotton fabrics. Artificial light did not affect the microcapsules. There is an impact on colour only when the capsules are printed to fabric. Both of the techniques used, printing and impregnation, have advantages as well as drawbacks.     

Effect of surfactants on the particle sizes of red#170 polyurea microcapsules

Red#170 (pigment) polyurea microcapsules have been successfully prepared at our laboratory. Both core and shell of these microcapsules are demonstrated to be red#170 pigment and polyurea, respectively, by infrared (IR) spectra. The number-average particle sizes of these microcapsules are seen to decrease with increasing concentration and the ethylene oxide chain length of nonylphenylpolyoxyethylene ether (NP_n; n = 6, 8, 10, 12, 16) as an emulsifier in the water phase used for making microcapsules. Experimental results indicate that the average particle sizes of red#170 polyurea microcapsules are smaller for the system with NP₁₆ than for the system with NP₄ (in the oil phase) and/or NP₁₆ (in the water phase) and that, in the presence of NP_n, these particle sizes are seen to be slightly smaller for use of methylcellulose than for use of sodium carboxymethylcellulose as a protective colloid. It is also interesting to note that the released amounts of red#170 pigment from polyurea microcapsules in di-n-butylphthalate solvent is lower for a system with NP ₁₆ than for a system with methylcellulose, as a result of good emulsification leading to decrease the interaction between toluene diisocyanate and water molecules. This may further cause more crosslinkage to take place at the urea groups, resulting in a decrease in the porosity of the capsules. © 1994 John Wiley & Sons, Inc.     

Synthesis of isocyanate microcapsules as functional crosslinking agent for wood adhesive

ABSTRACT

In this study, controlled-release isocyanate microcapsules were synthesized as functional crosslinking to slowdown the rate of cross-linking reactions. The isocyanate microcapsules were prepared by In-situ polymerization with polymethylene polyphenyl polyisocyanates (PAPI) as core and Urea formaldehyde resin as shell in oil-in-water emulsions. The particle size distribution, chemical structure, morphology, activity, and stability of the microcapsules were comprehensively characterized. Finally, the microcapsules were applied in a wood adhesive to prepare water-resistant plywood. The results showed that the size of the microcapsules was around 100 μm, the active content of NCO was about 23.5%, and the core content was approximately 80%. Compared with the stability of the bulk isocyanate, the stability of the isocyanate in microcapsules was significantly improved in the wood adhesive system. Furthermore, the isocyanate microcapsules showed highly efficient in plywood at different time, which indicated that isocyanate microcapsules could be controllable released in plywood applications.     

In vitro study of BSA gel/polyelectrolite complexes core shell microcapsules encapsulating doxorubicin for antitumoral targeted treatment

Abstract

The aim of this study is to develop core shell microcapsules of bovine serum albumin (BSA) gel with a complex polyelectrolite multilayer shell of natural polysaccharides with opposite charges, pectin (P), chitosan (Chi), and hyaluronic acid (HA) respectively, encapsulating Doxorubicin (Dox) as a carrier for targeted anti-tumoral treatment of hepatic cell carcinoma (HCC). A sacrificial CaCO₃ template method was used in order to obtain microcapsules with a BSA gel core and a layer-by-layer (Lbl) deposition technique of polyelectrolite complexes formed between P/Chi in the inner layers and HA/Chi in the outer shell layers. The preformed microcapsules, BSA gel/P/Chi/HA, noted as ms, have been applied for Dox encapsulation (ms-Dox). Dox encapsulation and release in different pH media were studied in order to elucidate the interactions between pH dependently charged species involved in the Dox loading/releasing processes. The structure characterization of ms/ms-Dox was evaluated by FTIR and UV-Vis spectroscopy, X-ray diffraction, thermal analy sis, optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy. The in vitro study for citotoxicity assessment on normal and tumoral cells of both ms and ms-Dox was performed using mesenchymal stem cells (MSCs) and Hep2G HCC cell lines. Results of physical-chemical analyses confirm the successful encapsulation of Dox in ms, and the in vitro biological study recommends ms-Dox as a candidate for future in vivo research as a targeted anti-tumoral treatment modality applications.     

Confocal microscopy study of polymer microcapsules for enzyme immobilisation in paper substrates

The goal of this research is to develop the technology platform required for the production of bioactive paper based on enzymes as bioactive agents. The immobilization platform described here is based on microencapsulation, which consists in the entrapment of biomolecules in the core of hollow spheres made by a semipermeable membrane. The capsules containing the enzymes can be either deposited on paper or mixed with paper pulp to prepare a bioactive paper. The activity of encapsulated laccase was compared with that of free enzyme using its reaction with the o‐phenylenediamine (OPD) substrate. Confocal Laser Scanning Microscopy (CLSM) is used to study the location of protein in microcapsules and provides explanations for differences in activity of encapsulated laccase. The location of protein in microcapsules was determined using BSA modified with the fluorescent tag sulforhodamine. Polyethyleneimine microcapsules were modified with fluorescein isothiocyanate allowing the simultaneous identification of capsule walls and of encapsulated proteins. From CLSM analysis, proteins were found to favor the wall of the capsules because of strong ionic attraction with the charged polymer. BSA was found to some extent in the core of the capsules and encapsulation of higher loadings increased the proportion of core proteins. We will also present our results on the incorporation of microcapsules in a paper substrate. CLSM was used in this section to determine the distribution and density of tagged microcapsules in the paper substrate. The response of immobilized laccase to a common substrate will also be described. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-glycidyl methacrylate) walled thermochromic microcapsules and their application to cotton fabrics

This study focused on fabrication of the thermochromic microcapsules and their application to the cotton fabric. In this study, thermochromic systems composed of crystal violet lactone, bisphenol A, and 1-tetradecanol were prepared and microencapsulated by emulsion polymerization method in poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-glycidyl methacrylate) wall. The microcapsules were analyzed by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, differential scanning calorimetry, and thermogravimetric analysis. Their thermoregulating property was tested by T-history test. The results revealed that microcapsules with smooth surfaces, core–shell structured, and spherical shape were successfully produced. The latent heat storage capacity of the microcapsules decreased from 202 J g⁻¹ to 167 J g⁻¹ when their shell/core ratio changed from 0.5/1 to 2/1. Microcapsules were adequately had sufficient thermal resistance to the temperatures they will encounter during their application to textile products and their usage. According to the UV–visible spectroscopy analysis and color measurements, the microcapsules exhibited reversible color change from blue to colorless and vice versa. Besides, the microcapsule impregnated fabric was able to absorb latent heat energy of 21.79 J g⁻¹ at around 35 °C and had cooling effect. According to the colorimetric parameters, the fabric was at blue color at room temperature and became colorless when heated to the temperature above the melting point of thermochromic system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48815.     

Preparation and characterization of paraffin microcapsules for energy-saving applications

A series of microencapsulated phase-change materials (PCMs) with styrene–divinyl benzene shells composed of an n-octadecane (OD or C₁₈)–n-hexadecane (HD or C₁₆) mixture as the core were synthesized by an emulsion polymerization method. The effects of the core/shell ratio (C/S) and surfactant concentration (C_surf) on the thermal properties and encapsulation ratios of the PCMs were investigated. The chemical structures and morphological properties of the microcapsules were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy analysis, respectively. The characteristic peaks of the paraffin mixtures and shell material located in the FTIR spectrum of the microencapsulated PCMs proved that the encapsulation of the PCM mixture was performed successfully. The thermal properties of the paraffin microcapsules were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis. DSC analysis demonstrated that the microcapsules containing the maximum amount of paraffin mixture (C/S = 2:1) and the minimum C_surf (45 mmol/L) had the highest latent heat value of 88 kJ/kg and a latent heat of temperature of 21.06°C. Moreover, the maximum encapsulation ratio of the paraffin mixture was found to be 56.77%. With respect to the analysis results, the encapsulated binary mixture, which consisted of OD–HD with a poly(styrene-co-divinyl benzene) shell, is a promising material for thermal energy storage applications operating at low temperatures, such as in the thermal control of indoor temperatures and air-conditioning applications in buildings for desirable thermal comfort and energy conservation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47874.     

Microcapsules application in graphic arts industry: a review on the state-of-the-art

The process of oil-containing microcapsules production by complex coacervation of gelatine and gum arabic was patented in 1957. Microencapsulation technology gained importance in production of carbonless copy paper as one of the most important commercial products. Development of this technology in later years led to the emergence of different types of microcapsules and the production procedures for various application fields. Nowadays, they are mainly used in medicine, pharmacy, agriculture, construction industry, chemical industry, food industry, biotechnology, cosmetic industry, photography, electronics, textiles and printing industry. This review paper highlights the major types of microcapsules and their applications in production techniques in graphic arts and printing industry, various processing parameters that affect their important characteristics and methods for microcapsules characterization. This paper discusses the applications of microcapsules within printing industry, and feasible printing technologies related to the desired substrate materials. The analysis of these subjects offers a deeper insight into the mechanisms of microcapsule transfer processes, their behavior, and working conditions leading to the final products. It reveals the advantages and the drawbacks of certain printing technologies for microcapsules transfer, which enables the determination of favorable transfer procedure for specific microcapsule type and substrate materials. This paper also provides valuable recommendations and potential solutions on how to overcome the obstacles created by certain printing technologies.     

Synthesis and characterization of chitosan/urea‐formaldehyde shell microcapsules containing dicyclopentadiene

Microcapsules containing healing agent have been used to develop the self‐healing composites. These microcapsules must possess special properties during the use of composites such as stability in surrounding, appropriate mechanical strength, and lower permeability. A new series of microcapsules containing dicyclopentadiene with chitosan/urea‐formaldehyde copolymer as shell materials were synthesized by in situ copolymerization technology. The microencapsulating mechanism was discussed and the process was explained. Also, the factors influencing the preparation of microcapsules were analyzed. The morphology and shell wall thickness of microcapsules were observed by using scanning electron microscopy. The size of microcapsules was measured using optical microscope and the size distribution was investigated based on data sets of at least 200 measurements. The chemical structure and thermal properties of microcapsules were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis, respectively. The storage stability and isothermal aging experiment of microcapsules were also investigated. Results indicted that the chitosan/urea‐formaldehyde microcapsules containing dicyclopentadiene were synthesized successfully; the copolymerization occurred between chitosan and urea‐formaldehyde prepolymer. The microcapsule size is in the range of 10–160 μm with an average of 45 μm. The shell thickness of microcapsules is in the range of 1–7 μm and the core content of microcapsules is 67%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microencapsulation of oil soluble polyaspartic acid ester and isophorone diisocyanate and their application in self-healing anticorrosive epoxy resin

Isocyanate and amine solution are microencapsulated, respectively, via in situ polymerization to realize the self-healing function in epoxy matrix. First, the isophorone diisocyanate (IPDI) microcapsules prepared with different core/shell ratios, emulsifier dosages and emulsification rates are characterized by field emission scanning electron microscope (FE-SEM). They exhibit integral spherical shape when the core/shell ratio is 3:1 and emulsifier concentration is 2.52 wt %, and the diameter of IPDI microcapsules ranged from 2.66 μm to 11.25 μm is manufactured by adjusting emulsification rate over the range of 3000–9000 rpm. Besides, during the microencapsulation of polyaspartic acid ester (PAE), urea, tung oil, as well as aqueous isocyanate are proposed to improve the stability of PAE emulsion. SEM and FTIR results reveal that aqueous isocyanate can react with partial PAE and form polyurea (PU) layer to take protection effectively. Further, IPDI-PAE dual microcapsules are incorporated into epoxy coatings, the self-healing and anticorrosion performance of coatings with various amounts of microcapsules are investigated systematically. It was found that the degree of repair and anticorrosion are increased with increasing microcapsules loading, and the appropriate amount of microcapsules addition is 15 wt %, which corresponding to 93% repair efficiency. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48478.     

Fabrication of sustained‐release and antibacterial citronella oil‐loaded composite microcapsules based on Pickering emulsion templates

In this work, the citronella oil (CTO)‐loaded composite microcapsules with hydroxyapatite (HAp)/quaternary ammonium salt of chitosan (HACC)/sodium alginate (SA) shells are facilely and effectively fabricated by templating citronella oil‐in‐water Pickering emulsions, which are stabilized with HAp nanoparticles. The microcapsule composite shells are prepared by the electrostatic adsorption of HACC and SA, and then chelation interaction of alginate and Ca²⁺ ions released from HAp nanoparticles. Scanning electronic microscope observation shows that the microcapsules have a spherical shape. Thereafter, Fourier transform infrared spectroscopy and thermal gravimetric analysis results indicate that CTO is successfully loaded into the microcapsules, and the related CTO‐loaded microcapsules possess the thermal stability. Moreover, the in vitro release study of CTO shows that the microcapsules have sustained release activity, and the related CTO release profiles can be well described by Rigter–Peppas model. The antimicrobial assays of microcapsules display the antibacterial effect of CTO‐loaded microcapsules against Staphylococcus aureus and Escherichia coli. Overall, this study opens up new potentiality for unstable active ingredient as an environmental friendly and ingenious microencapsulation in food and agriculture applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46386.     

Core content and stability of n‐octadecane‐containing polyurea microencapsules produced by interfacial polymerization

Microencapsulation of phase change material (PCM) n‐octadecane was carried out by interfacial polymerization technique using core and bulk monomers as toluene‐2,4‐diisocyanate (TDI) and diethylene triamine (DETA), respectively. Cyclohexane was used as the solvent for TDI and n‐octadecane, which formed the oil phase. The effect of encapsulation procedure, core‐to‐monomer ratio (CM ratio) and PCM‐to‐cyclohexane (PC) ratio was investigated on core content, encapsulation efficiency, and stability of microcapsules. Using a modified procedure, the core content was found to increase with the increasing CM ratio and reached a maximum at 3.7, while the encapsulation efficiency continuously decreased with the increasing CM ratio. Also the encapsulation efficiency was found to have a strong dependence on PC ratio and a maximum encapsulation efficiency of 92%, along with the core content of 70% was obtained with CM ratio of 3.7 along with the PC ratio of 6. The microcapsules were well shaped, i.e., round and regular, with narrow size distribution at these conditions. The PCM microcapsules were found to be stable to heat treatment at 150°C for 8 h. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation and characterization of double‐MF shell microPCMs used in building materials

A kind of double‐shell heat energy storage microcapsule was prepared used melamine formaldehyde (MF) resin as shell material, and the properties of the microcapsules were investigated. A phase change material, with melt point of 24°C and phase transition heat of 225.5J/g, was used as core. The microcapsules would be used in indoor walls to regulate the temperature and save energy. The surface morphological structure was examined by means of scanning electron microscopy. The strength of the shell was evaluated through observing the surface change after pressure by means of scanning electron microscopy. The average diameter of the microcapsules was 5 μm ～ 10 μm. Diameter of 1 μm ～ 5 μm could also be obtained by using different stirring speeds. The globular surface was smooth and compact. The thickness was 0.5 μm ～ 1 μm. Also, the melting point of the microcapsules was 24.7°C, nearly equal to the pure phase change material. The DSC results make clear that the polymer shell of the microcapsules does not influence the properties of the phase change material. It was also found that the avoiding penetration property of the double‐shell microcapsules was better than that of single shell, and the average diameter of 5 μm was better than 1 μm. With the increase of ratio of the core material, the compactability decreased, and the shell thickness decreased. The mass ratio of core and shell was 3 : 1 to ensure that the microcapsules had good heat storage function. The measuring test showed that the microcapsules did not rupture at a pressure of 1.96 × 10⁵ Pa. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1755–1762, 2005     

Preparation and characterization of controlled-release poly(melamine-formaldehyde) microcapsules filled with 2,4-D isooctyl ester

A novel 2,4-D isooctyl ester microcapsules suspension was prepared through in situ polymerization method. The preparation and characterization of poly(melamine-formaldehyde) microcapsules filled with 2,4-D isooctyl ester with different weight ratios of shell material to core material were performed. Results showed that the microcapsules had much better performance. The accumulative release profiles and the Peppas mathematical model indicated that microcapsules had the performance to prolong the sustainable release time up to 30 days with the release behavior of anomalous transport. Meanwhile, less organic solvents were used throughout the preparation process and the preparation method was environmental friendly.     

Stabilization of Microcapsules Using a Freeze-Dried Gelatin Matrix: Aqueous Redispersibility and the Ingredient Activity

Microcapsules are of great interest to the food and pharmaceutical industries as vehicles to deliver active ingredients to the gastrointestinal tract. Drying plays an important role in stabilizing microcapsules to prolong their lifetime; however, drying often produces undesirable changes in the microcapsules, such as irreversible aggregation of the microcapsules and activity loss of the encapsulated ingredient. In this work, poly(epsilon-caprolactone) microcapsules containing a model bioactive compound (tocopherol) were prepared and stabilized in a freeze-dried gelatin matrix. This dried product was rehydrated and the aqueous redispersibility of the microcapsules and the tocopherol activity were investigated. The experimental results suggested that a kinetic balance between dehydration (caused by freezing) and gel network formation is a critical factor that affects the redispersibility and ingredient activity of the products. It was further suggested that a hydrogel-based product could be strategically freeze dried to maximize product quality by tuning its freezing process; that is, by employing a controllable dehydration process.     

Mechanical properties and drug release of microcapsules containing quaternized‐chitosan‐modified reduced graphene oxide in the capsular wall

Reduced graphene oxide (rGO) sheets were first modified with 2‐hydroxypropyltrimethyl ammonium chloride chitosan (HACC), and these modified rGO sheets (named HACC–rGO) were used as reinforcement materials and introduced to the walls of chitosan (CS) microcapsules. All of the monodisperse microcapsules were conveniently generated by a gas–liquid microfluidic technique. The results of scanning electron microscopy, X‐ray diffraction, and thermogravimetric analysis all demonstrate that the HACC–rGO sheets existed and were dispersed in the capsular shell. The HACC–rGO‐reinforced CS microcapsules showed better mechanical strength and better chemical stability with an α‐cyclodextrin solution than the CS microcapsules without HACC–rGO. Importantly, the HACC–rGO‐reinforced CS microcapsules exhibited a slower drug‐release behavior and provide a method for the control of the release rate of drug‐loaded microcapsules. In an in vitro cytotoxicity evaluation by a 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide assay, the Schwann cells still showed good cell viability after they were treated by extracts of the CS/HACC–rGO microcapsules with concentrations ranging from 0.02 to 2000 μg/mL. Therefore, the HACC–rGO‐reinforced CS microcapsules are promising for applications in the fields of drug delivery and controlled release. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44549.     

Porous ultrathin-shell microcapsules designed by microfluidics for selective permeation and stimuli-triggered release

Microcapsules are versatile delivery vehicles and widely used in various areas. Generally, microcapsules with solid shells lack selective permeation and only exhibit a simple release mode. Here, we use ultrathin-shell water-in-oil-in-water double emulsions as templates and design porous ultrathin-shell microcapsules for selective permeation and multiple stimuli-triggered release. After preparation of double emulsions by microfluidic devices, negatively charged shellac nanoparticles dispersed in the inner water core electrostatically complex with positively charged telechelic α,ω-diamino functionalized polydimethylsiloxane polymers dissolved in the middle oil shell at the water/oil interface, thus forming a porous shell of shellac nanoparticles cross-linked by telechelic polymers. Subsequently, the double emulsions become porous microcapsules upon evaporation of the middle oil phase. The porous ultrathin-shell microcapsules exhibit excellent properties, including tunable size, selective permeation and stimuli-triggered release. Small molecules or particles can diffuse across the shell, while large molecules or particles are encapsulated in the core, and release of the encapsulated cargos can be triggered by osmotic shock or a pH change. Due to their unique performance, porous ultrathin-shell microcapsules present promising platforms for various applications, such as drug delivery.     

Preparation,characterization, and prominent thermal stability of phase‐change microcapsules with phenolic resin shell and n‐hexadecane core

Microcapsules with phenolic resin (PFR) shell and n‐hexadecane (HD) core were prepared by controlled precipitation of the polymer from droplets of oil‐in‐water emulsion, followed by a heat‐curing process. The droplets of the oil phase are composed of a polymer (PFR), a good solvent (ethyl acetate), and a poor solvent (HD) for the polymer. Removal of the good solvent from the droplets leads to the formation of microcapsules with the poor solvent encapsulated by the polymer. The microstructure, morphology, and phase‐change property as well as thermal stability of the microcapsules were systematically characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimety (DSC), and thermogravimetric analysis (TGA). The phase‐change microcapsules exhibit smooth and perfect structure, and the shell thickness is a constant fraction of the capsule radius. The initial weight loss temperature of the microcapsules was determined to be 330°C in N₂ and 255°C in air, respectively, while that of the bulk HD is only about 120°C both in air and N₂ atmospheres. The weight loss mechanism of the microcapsules in different atmosphere is not the same, changing from the pyrolysis temperature of the core material in N₂ to the evaporation of core material caused by the fracture of shell material in air. The melting point of HD in microcapsules is slightly lower than that of bulk HD, and a supercooling was observed upon crystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007