Preparation Of Microcapsules Research Articles

Preparation of pH-stabilized microcapsules for controlled release of DEET via novel CS deposition and complex coacervation

In order to slow down the volatilization rate of N, N-Diethyl-m-toluidine (DEET) and enhance its safe application, an improved complex coacervation method was developed to encapsulated it to prepare microcapsules with the function of mosquito repellent. Tannic acid as a cross-linking agent for gelatin and Arabic gum enhanced the structural stability of the capsule through hydrogen bonding. Chitosan was selected to further deposited on the surface of G/AG MC for the improvement of pH stability and formed CS-G/AG MC. Scanning electron microscopy and optical microscope confirmed the chitosan was successful deposited on the G/AG MC, which ameliorated the agglomeration of microcapsules and promoted their monodispersity. Fourier transform infrared spectroscopy confirmed that electrostatic attraction accounted predominantly for the forces between the shell materials. The deposition of chitosan imparted controlled release to the microcapsules, resulting in a high retention efficacy of DEET in the pH range of 2–10. The CS-G/AG MC showed good storage stability and biocompatibility, and the static leakage of DEET within 40 days was negligible. The microcapsules prepared by this method showed green ecological properties, derived from the natural origin and biocompatibility of the shell material. And the tight structure of the microcapsule shell effectively barriered the volatile of DEET, while greatly extending its release time. This study can effectively protect the biological activity of core materials of microcapsules, and has long-lasting release performance, which has potential economic benefits in personal care products market directly contacted by humans.

Preparation of multifunctional phase change microcapsules for thermal energy storage and shielding against ionizing radiation

A novel type of multifunctional microencapsulated phase change materials (MPCMs) with BaCO3 as shell and binary phase change materials (PCMs) as core was prepared based on self-assembly method. In addition to their original thermal storage properties, MPCMs are endowed with the ability to shield against ionizing radiation by the BaCO3 shell containing high atomic number element Ba2+. Thermal analysis indicated that due to the composition of binary PCMs, MPCMs had phase transition points of 5.54 °C and 32.6 °C, which enabled MPCMs with thermal storage function in wide temperature ranges. Furthermore, the cement paste containing different replacement ratio of MPCMs was exposed to X-ray radiation. The results showed that with the addition of MPCMs, the linear attenuation coefficient of cement paste had a general increase over the photon energy range of 0.05–0.15 MeV, especially at the lower photon energy. The multifunctional MPCMs developed in this study provides applicability for traditional thermal storage materials in building and other fields.

Preparation and characterization of phase change material microcapsules with modified halloysite nanotube for controlling temperature in the building

Microencapsulated phase change material (mPCM) with effective heat transfer and flame retardant is highly desirable given today’s increasing energy demand. In this article, the halloysite nanotube (D-HNT) was modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and then inserted into the mPCM (D-H-mPCM) successfully. The transmission electron microscope, X-ray photoelectron spectroscopy and FT-IR results showed that the DOPO is grafted in both interior and exterior walls of halloysite nanotube (HNT), and the D-HNT is successfully inserted into mPCM. According to thermogravimetric analysis tests, D-H-mPCM was the best thermally stable sample among other mPCM for the existence of HNT and DOPO. The differential scanning calorimetry tests showed that the latent heat of D-H-mPCM was 113.52 J/g, and the D-HNT embedded in the mPCM greatly contributes to the heat transfer of the PMMA shell. To detect the flame retardancy and temperature control performance of mPCM samples, D-H-mPCM was incorporated into epoxy resin (EP-D-H-mPCM). The data of the cone calorimeter test suggested the EP-D-H-mPCM exhibited the lowest peak of heat release rate (pHRR) and total heat release (THR) of 572.65 kW/m2 and 93.95 MJ/m2 respectively. Finally, the small room model test and infrared thermal imager test showed the application of D-H-mPCM in EP can regulate indoor temperature and moderate temperature fluctuation. This work provides a new methodology to improve both thermal conductivity and flame retardancy of mPCM.

Preparation and properties of thermo-expandable microcapsules with anionic/nonionic waterborne polyurethane as the shell

Preparation and properties of thermo-expandable microcapsules with anionic/nonionic waterborne polyurethane as the shell

Preparation of microcapsules with IPDI monomer and isocyanate prepolymer as self-healing agent and their application in self-healing materials

Microcapsules were synthesized with the hybrid of Isophorone diisocyanate (IPDI) and terminal isocyanate prepolymer (CPU) as active healing agent, then the microcapsules were mixed with epoxy resin in order to form a metal anti-corrosion coating with excellent self-healing properties. Through process optimization and molecular design, the core material which was isocyanate hybrid (CPU-IPDI) with 17% Isocyanate group (-NCO) was synthesized by the reaction of IPDI and castor oil, and then the CPU-IPDI was encapsulated in the microcapsule with Diphenylmethane diisocyanate (MDI) as the shell by interface polymerization. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric spectroscopy (TGA) confirmed the successful encapsulation of CPU-IPDI. The effect of the content of sodium lignosulfonate (NaLS) on the size and morphology of microcapsules were investigated. Optical microscopy (OM) and laser particle size analyzer show that the size of microcapsules decreases with the increase of the content of stabilizing agent. The microcapsules were prepared with 1% NaLS with a core content of 51.3%, an average particle size of 26.3 μm and a shell thickness of 1.44 ± 0.9 μm. In addition, the microcapsules loaded with CPU-IPDI were added to the epoxy coating, and the healing process of blank coating and self-healing coating was detected by SEM. The results show that the coating wound of containing 10% microcapsules has obvious healing. With saline infiltration and electrochemical impedance spectroscopy (EIS) test coating corrosion process, the results prove that after soaking in 3.5% NaCl solution for 7 days, the |Z| f = 0.01Hz value of the coating with 10 wt % microcapsules is about 1.9 × 106 Ω cm2, nearly three order higher than that of pure epoxy coating (3.1 × 103 Ω cm2), demonstrating the enhancement of protection ability.

Preparation of multicolor microcapsules and their application in smart color-switching textiles

Spiropyran and spiroxazine photochromics have attracted increasing attention in optical data storage, optical switches, and anti-counterfeiting for decades. To expand the applications of spiropyran and spiroxazine, the durability and multi-color changes of spiropyran and spiroxazine still need to be explored. In this article, based on the subtractive principle of dyes, multi-color spiropyran and spiroxazine microcapsules with uniform particle sizes were prepared by the interfacial polymerization method via using compounds (spiropyran and spiroxazine) of different colors as the core material, and polyurethane as the shell material. Among them, toluene diisocyanate and polyethylene glycol constitute the hard and soft segments of polyurethane, respectively. The color of spiropyran and spiroxazine microcapsules can effectively switch between color and colorless, showing excellent photo fatigue resistance. The average particle size of microcapsules is 2.951 µm, and the particle distribution index value is 0.314, which shows the particle size is small and uniform. The maximum thermal decomposition temperature is 426°C, demonstrating good thermal stability. The hydrophobic photochromic fabric was prepared by coating multi-color spiropyran and spiroxazine microcapsules on cotton knitted fabric and hydrophobic treatment. The hydrophobic photochromic fabric is hydrophobic and stain resistant, and exhibits multi-color dynamic switching and long-lasting use. After 50 cycles of washing, the water contact angle of the fabric remains about 109°, showing its good washing resistance and water repellency. In addition, spiropyran and spiroxazine microcapsules are also applied in template and screen printing to impart rich and dynamic color-changing effects to fabrics, fabricating photochromic fabrics. Photochromic fabrics have potential applications in civilian and military fields.

Effects of manufacturing conditions on the properties of boric acid/melamine-urea-formaldehyde microcapsules prepared by in situ polymerization: Its inhibition behavior on wood destroying fungi

Water-soluble boric acid (BA) was microencapsulated by in situ polymerization with a melamine-urea formaldehyde shell. The effects of core-shell ratio, time, and temperature on the microcapsule characteristics were investigated. The microencapsulated BA was tested for its effectiveness against wood-destroying fungi. The results showed that the core:shell ratio affected the individuality of the microcapsules (MCs), and the most individual microcapsules were those with the 1:1 core:shell ratio. The microencapsulation temperature at the 1:1 core:shell ratio affected the surface porosity and size spectrum of MCs. The surface was porous, and the size spectrum was narrow at 50 °C. The microencapsulation reaction time at the 1:1 core-shell ratio did not have a considerable effect on the MC size. Although the MC size spectrum varied in the studied parameters (core: shell ratio, temperature, time), the average MC sizes were large enough to pass through the bordered pits of the softwood cell wall. Slow boron release was obtained by optimizing the MC preparation parameters. The optimum microencapsulation parameters for slow release of BA were the 1:1 core:shell ratio, 50 °C, and time of 120 min. The capsules produced at optimum microencapsulation parameters were biologically active against the fungus Coniophora puteana and leaching resistance was improved.

Preparation and characterization of Perilla essential oil composite microcapsule based on the complex coacervation and interface polymerization.

In this paper, we prepared a novel double-layer Perilla essential oil composite membrane microcapsule (PEOCM) by the composite methods of complex coacervation and interface polymerization. The particle size distribution, morphology, pressure resistance, thermal stability, and elemental proportions of the microcapsule shell of the obtained microcapsules were characterized by laser particle size analyzer, scanning electron microscopy (SEM), dynamic rheometer, thermogravimetric analysis (TGA), and energy spectrometer. In order to further examine the application effect of the PEOCM, we carried out a fresh-keeping experiment on nectarines. The results showed that the average volume diameter of the microcapsules was 226.9µm, with a completely spherical shape and a slight depression on the surface and had good pressure resistance and thermal stability. The results also demonstrated that microencapsulation does not change the composition of Perilla essential oil, and the polyurea membrane with amide structure (-NH-CO-NH-) was formed successfully. Furthermore, the total soluble solids content and peroxidase activity of nectarines indicated that the PEOCM can be a preservative of food. PRACTICAL APPLICATION: We prepared a double-layer Perilla essential oil composite membrane microcapsule by the composite methods of complex coacervation and interface polymerization. The encapsulation conditions of the microcapsules were optimized, the structure of the microcapsule was characterized, and the fresh-keeping effects of the microcapsule on nectarine were studied. The results showed that microcapsules had a completely spherical shape and a slight depression on the surface and had good pressure resistance, good thermal stability, and good fresh-keeping ability. The above characteristics indicated that the double-layer microcapsules have good application prospect and plays an important role in food fresh-keeping and the preservation of essential oils.

Preparation of Resin-Coated Waterborne Coating Microcapsules and Its Effect on the Properties of Waterborne Coating for Wood Surfaces

In this paper, the related experiments were carried out on microcapsules, with the aim of making the prepolymer react with the core emulsion by in situ polymerization using urea–formaldehyde resin as the wall material and waterborne acrylic wood coating as the core material. The prepared microcapsules were added to the waterborne acrylic wood coating and brushed on wood boards. Then, the gloss, hardness, adhesion, impact resistance and color difference were compared with paint surfaces without microcapsules. When the ratio of the microcapsule core-to-wall material was different from the increase in microcapsule content, the gloss of the coating decreased continuously; the decreasing range was basically the same, and the gloss values of the three core-wall ratio microcapsules were rather similar. With the increase in microcapsule content, the impact resistance of the coating first increased and then decreased. With the increase in microcapsule content, the color difference of the coating also increased continuously. The color difference of the coating with a microcapsule core-wall ratio of 0.67 changed the least, and the coating performance was good. When the core-wall ratio of the microcapsules was 0.67, and the proportion of microcapsules in the paint was 7.0%, the comprehensive properties of this coating were good. This research is of great significance to the future protection and development of wood.

The preparation and characterization of thermal expansion capric acid microcapsules for controlling temperature

Although the microencapsulation technology can encapsulate the organic phase change materials (PCMs), the vaporized PCMs break the microencapsulation at a high temperature and can be ignited before the polymer materials, which contributes to the fire spread. The thermal expansion capric acid (CA) microcapsules (TCAMs) were successfully fabricated based on polyurethane/polyacrylate in this study, which can prevent the capric acid from escaping at a high temperature and increase the temperature control ability. The results indicated that the diameter of TCAMs after heat treatment increases from 100 μm to 400 μm. The vaporized capric acid broke the microcapsule between 220 °C and 280 °C. Although the phase change behavior of TCAMs was similar to that of normal microcapsules, the residues of TCAMs after heat treatment were much higher. The result from small room model test also proved that the TCAMs have more robust and stable temperature control ability. Because the capric acid containing high content of C and H contributed to the combustion of composite, the normal microcapsules increased the heat release rate of the composite to 366.27 kW/m2, while the heat release rate of the composite containing TCAMs was 332.88 kW/m2 because the thermal expansion shell prevented liquid and vaporized CA from leaking.

Effect of Urea–Formaldehyde Resin–Coated Colour–Change Powder Microcapsules on Performance of Waterborne Coatings for Wood Surfaces

Microcapsules have received a great deal of attention from researchers due to their excellent properties, and are commonly prepared by interfacial and in situ polymerisation methods. In situ polymerisation is an important method of microcapsule preparation, which has a number of advantages such as low cost and suitability for industrial production. Microencapsulation is used to modify the state of the material in order to improve its practical usability and mechanical and optical properties. In this paper, urea–formaldehyde resin–coated colour–changing powder microcapsules were prepared and their properties were used to study the colour–changing properties of wood surface coatings, and the mechanical and optical properties of waterborne paint films incorporating colour–changing powder microcapsules were tested. The results show that as the microcapsule content increases, the colour–change effect of the coating gradually becomes obvious and the amount of change in the b–value representing the yellow hue gradually increases. As the microcapsule content increased from 1.0% to 13.0%, the b–value increased from 0.7 to 2.6. The gloss of the film decreased significantly with the increase in the microcapsule content of the colour–change powder, with the highest gloss at 1.0%. The impact resistance of the film was also influenced by the content of microcapsules in the waterborne topcoat, with the best impact resistance at 5.0%, level 2 of adhesion at 1.0%–5.0% and 11.0%–13.0%, and level 1 of adhesion at 7.0% and 9.0%. In terms of mechanical and optical properties, the 5.0% content of colour–changing powder microcapsules is the best for the overall performance of waterborne topcoats. In practical furniture applications, the microcapsules prepared in this paper can change the colour in appearance according to the actual temperature and play a decorative role.

Preparation and characterization of multifunctional phase change material microcapsules with modified carbon nanotubes for improving the thermal comfort level of buildings

Excellent temperature regulation and flame retardancy are the keys to the wide application of phase change material microcapsules (MPCMs) in building fields. In this study, the flame retardant carbon nanotube (d-CNT) modified by 9,10-dihydro-9-oxa-10 phosphaphenanthrene-10-oxide (DOPO) was successfully embedded into the MPCM (d-c-MPCM) by in-situ polymerization. The scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) experimental results showed that DOPO was grafted onto the carbon nanotube (CNT) surface and the d-CNT was successfully added to the microcapsule with a particle size of 150 nm. The d-c-MPCM displayed better thermal stability than other MPCMs due to the presence of CNT and DOPO, which was demonstrated by thermogravimetric analysis (TGA) and micro-combustion calorimeter (MCC) tests. The differential scanning calorimetry (DSC) results of MPCMs showed that the phase transition temperature and latent heat of d-c-MPCM are 31.14 ℃ and 103.21 J/g, respectively. The flame retardancy and temperature control ability of microcapsules were detected by adding d-c-MPCM to the rigid polyurethane foam (RPUF/d-c-MPCM). In the cone calorimeter test, RPUF/d-c-MPCM significantly reduced the heat release and increased the residual mass of foam during combustion. These improvements in thermal stability and flame retardancy resulted from the synergistic effect of CNT and DOPO on the formation of char layer. Finally, the small room model and infrared thermal imager results proved that RPUF/d-c-MPCM made indoor temperature fluctuation more gentle, and the maximum indoor temperature is only 26.6 ℃. These unique properties will significantly facilitate the practical application of the MPCMs in building insulation materials.

Preparation and Evaluation of Taste Masked Paracetamol Microcapsules

Paracetamol (PAR) is widely used for pediatric and geriatric patients to treat pain and fever, but it has an extremely bitter taste which poses a challenge to be formulated into suitable oral dosage forms for these age categories. This study was aimed to prepare taste-masked paracetamol microcapsules by temperature-induced phase separation technique using ethylcellulose (EC) as a wall polymer and calcium carbonate (CaCO3) as a gastro-soluble pore former. The effect of drug/polymer ratio and proportions of calcium carbonate in the wall on microcapsules characteristics were studied. The taste masking efficiency was evaluated using an in vitro dissolution model simulating oral cavity conditions. The optimized formulation was characterized by FT-IR and SEM. Results show that the particle size and the drug release in 0.1 N HCl (pH 1.2) were dependent on the drug/polymer ratio and the proportion of calcium carbonate in the wall. FT-IR spectroscopy of PAR microcapsules showed no interaction between drug and polymer. The in vitro taste masking evaluation of microparticles F8 with a drug/polymer ratio (8/1), which achieved the percent drug release more than 75% at 30min in 0.1N HCL, showed efficient taste-masking of PAR compared to the bitterness threshold.

Preparation and evaluation of microcapsules containing Rimulus Cinnamon and Angelica Sinenis essential oils

Starch sodium octenyl succinate (SSOS) and maltodextrin (MD) are commonly used as wall materials to protect bioactive compounds, such as essential oils volatiles. In this work, Rimulus Cinamon (RC) and Angelica Sinenis (AS) essential oils (EOs) were encapsulated in (SSOS/MD) composite capsules via spray drying. The microcapsules were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric (TG). The particle size, Zeta potential, drug loading (DL), encapsulation efficiency (EE), stability and in vitro release of the EOs microcapsules were investigated. The average particle size of microcapsules and emulsion was 12.6 ± 1.09 μm and 0.22 ± 0.01 μm, respectively. The DL% and EE% of microcapsules were 16.3 ± 0.40% and 96.6 ± 1.17%. No phase separation was found in the emulsion within 7 d, and the creaming index was 0%, showing good stability. After 6 months of storage, the retention rate of cinnamaldehyde in the microcapsules was about 67.6%, which significantly improved the stability of EOs. Thus, SSOS/MD can efficiently encapsulate EOs with high drug loading, encapsulation efficiency and stability.

Preparation of Melamine-Formaldehyde Resin/Rice Husk Powder Coated Epoxy Resin Microcapsules and Effects of Different Microcapsule Contents on the Properties of Waterborne Coatings on Tilia europaea Surface

With the development of economy and science and technology, people put forward higher standards for the performance of the surface coating of wood products, which requires us to carry out innovative research on the coating. In this work, a kind of microcapsule was prepared with melamine-formaldehyde resin/rice husk powder as wall material and epoxy resin as core material. The microcapsules were added to the waterborne acrylic resin coating according to the contents of 0%, 1.0%, 4.0%, 7.0%, 10.0%, 13.0%, 16.0% and 20.0% respectively, and were coated on the surface of the Tilia europaea boards in the form of topcoat. The effects of different contents of microcapsules on the optical properties, mechanical properties and aging resistance of the coating were explored, and the optimal content that can effectively improve the properties of the coating was analyzed. Test results indicated that when the microcapsule content is 7.0%, the comprehensive properties of the coating is optimal. At this time, the color difference of the coating is 6.96, the gloss at 60° is 13.4%, the hardness is 2H, the adhesion grade is 1, and the impact resistance is 12.0 kg·cm. After the aging test, the gloss loss rate decreases, the color difference is 5.69, and the gloss at 60° is 11.6%. The results of aging test show that the coating with epoxy microcapsules has a certain self-healing function. In this study, the microcapsules which can optimize the mechanical properties waterborne coating and prolong the service life of wood were prepared. This can meet the diverse needs of consumers, supply a theoretical reference for the preparation of functional microcapsules, and provide reference value for the functional research of the coating on wood furniture surface.

Tung Oil Microcapsules Prepared with Different Emulsifiers and Their Effects on the Properties of Coating Film

In water-based coatings, the addition of tung oil microcapsules coated with urea formaldehyde resin (UF) can effectively repair the microcracks in the coating film on the surface of wood. The tung oil as a repairing agent plays an important role in the preparation of microcapsules. In this paper, Span-80, SDBS, OP-10, Tween-80 and SDS were used as five emulsifiers to study the influence of different emulsifiers on the preparation of tung oil microcapsules, and the properties of the coating film added to the waterborne coatings. According to the coating process of three bottoms and three sides, tung oil microcapsules were added to the water-based paint with a content of 12% and coated on the wood surface. The appearance and microstructure of the microcapsules, as well as the mechanical, optical and self-repairing properties of the paint film were analyzed to find out the best emulsifier suitable for the core material. The tung oil microcapsules prepared by Tween-80 have the best morphology, concentrated particle size distribution, particle size of 6–15 μm, and spherical morphology. The film with the microcapsules prepared by Tween-80 had the best performance, small color difference, high gloss, hardness of 5H, adhesion grade 1, elongation at break of 47.23%, impact resistance of 20 kg∙cm, and good toughness. At the same time, the repair rate reached 37.9%. The results provide the application reference for the use of self-repairing microcapsules in coatings.

Preparation of strawberry chitosan composite microcapsules and their application in textiles

Chitosan (CS) is often used as the shell material of microcapsules due to its natural non-toxic property. However, most of traditional CS microcapsules are single chamber microcapsules with single function. In this study, phase change CS microcapsules were firstly prepared by a single coagulation method, and then photochromic nanocapsules were grafted onto the CS microcapsules to obtain strawberry CS composite microcapsules. These microcapsules could be applied in the fabric, which endows it with good photochromic and antibacterial performances based on photochromic nanocapsules and CS shell of microcapsules. Through adjusting the covering density of nanocapsules on the CS microcapsules, the color-changing performance and antibacterial ability could be regulated. Moreover, it exhibited a good durable color-changing property even after repeatedly color fatigue resistance test, and the obtained multifunctional fabric is capable of thermal insulation property owing to the phase material in the microcapsules. This study provides guide for the preparation of CS-based microcapsules and high-performance textiles.

Preparation and Antibacterial Properties of Carvacrol-loaded Composite Microcapsules via Palygorskite-Stabilized Pickering Emulsions

AbstractEssential oils (including carvacrol, CAR) have been used in the medicinal and health field because of their broad-spectrum antibacterial activities. However, the volatility and pungent odor are still the greatest obstacles to wider application. The purpose of the present study was to address those problems by encapsulating the antibacterial CAR in palygorskite (Plg) by integrating it into Pickering emulsions with complex coacervation. The CAR in Pickering emulsion was formed firstly by stabilization with the CAR-modified Plg; then, the emulsion droplets were embedded and fixed in the microcapsule through the subsequent complex coacervation process, which occurred between the quaternary ammonium salt of chitooligosaccharides (HACC) and sodium alginate (SA) via calcium ions. The microcapsules obtained were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results demonstrated that the microcapsules presented a nearly sphere-like shape with a mean diameter of 3.5 mm but had a porous interior structure. The Plg plays multiple roles in the preparation process, including increasing the emulsion stability, improving the encapsulation efficiency of CAR, and the thermostability of microcapsules. The microcapsules showed remarkable antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and inhibition rates toward E. coli and S. aureus reached 100% when the microcapsules were encapsulated with 15 or 20% of CAR, respectively. The microcapsules obtained could be used as antibacterial agents in food preservatives, animal feed, and other health-related consumer products.

Preparation and Characterization of Methyl Jasmonate Microcapsules and Their Preserving Effects on Postharvest Potato Tuber.

Potato tubers tend to sprout during long-term storage, resulting in quality deterioration and shortened shelf life. Restrictions on the use of chlorpropham, the major potato sprout suppressant, have led to a need to seek alternative methods. In this study, the effects of methyl jasmonate (MeJA) solutions and MeJA microcapsules on sprouting and other key quality attributes of the potato tuber were investigated. The results showed that the MeJA solution was most effective at 300 μmol L−1 according to TOPSIS analysis. To prepare MeJA microcapsules, the optimal formulation is with 0.04% emulsifier, 2.5% sodium alginate, 0.5% chitosan and 3% CaCl2. Compared to 300 μmol L−1 MeJA solution, MeJA microcapsules consumed a lower dose of MeJA but demonstrated a better retaining effect on the overall quality attributes of potato tubers. MeJA microcapsules are promising agents for the preservation of postharvest potato tubers.

Preparation of Healable Shellac Microcapsules and Color-Changing Microcapsules and Their Effect on Properties of Surface Coatings on Hard Broad-Leaved Wood Substrates

In order to protect the wood surface and improve the properties of coatings, microcapsules with healable and discoloration functions are produced, and their healable function is obtained using shellac, which can be cured at room temperature, as the repairing agent. In this paper, self-made shellac microcapsules and color-changing microcapsules were added to varnish in different proportions to form the composite coating on a wood board, and the color difference of the coating was measured at different temperatures to study the influence of microcapsules on the degree of surface color on the substrate. The effect of microcapsules on the healable performance of coatings on a wood board was studied by scratching the surface of the coating with a utility knife and observing the process of repair. The optimal sample was selected from the orthogonal experiment for the independent experiment. The surface roughness, hardness, infrared spectrum, and scanning electron microscopy of the optimal sample were tested, and the content in the optimal sample was further investigated. The results show that color-changing microcapsules have a color-changing effect on surface coatings based on wood boards, and shellac microcapsules inhibit the color-changing effect of color-changing microcapsules. Composite microcapsules can repair the cracks on the surface coatings of wood boards. In cases where shellac microcapsules can self-repair the coating, the color-changing effect is best when the content of color-changing powder is 15.0%.