程 辉，赵梦雪，毋 伟

北京化工大学 化学工程学院 北京 100029

引用格式：

程辉，赵梦雪，毋伟. 亲水性石墨烯@TiO₂@石蜡光热相变微胶囊的制备及性能［J］. 中国粉体技术，2025，31（1）：1-11.

CHENG Hui， ZHAO Mengxue， WU Wei. Preparation and properties of hydrophilic graphene@TiO₂@paraffin photothermal phase change microcapsules［J］. China Powder Science and Technology，2025，31（1）：1−11.

DOI：10.13732/j.issn.1008-5548.2025.01.001

收稿日期：2024-06-28，修回日期：2024-09-14，上线日期：2024-10-12。

基金项目：国家自然科学基金项目，编号 ：21676023。

第一作者简介：程辉（1999—），男，硕士生，研究方向为相变材料的制备及应用。E-mail：15629621293@163. com。

通信作者简介：毋伟（1966—），男，教授，博士，博士生导师，研究方向为化工新型材料的制备及应用。E-mail：wuwei@mail. buct. edu. cn。

摘要：【目的】 解决光热相变材料（phase change materials，PCMs）在实际光热储存领域中存在易泄漏、导热以及光热转换效率低的问题。【方法】 采用微胶囊法，氧化石墨液相剥离可膨石墨制备亲水性石墨烯，亲水性石墨烯与无机材料TiO₂复合作为壳层，以石蜡为核，制备复合相变微胶囊，系统研究了微胶囊性能。【结果】 亲水性石墨烯添加量（质量分数）为1%时，制备的微胶囊为形状规则的球形结构，泄漏率为 6. 90%，热导率为 0. 459 W/（m·K），熔融焓为 84. 58 J/g，结晶焓为91. 26 J/g，微胶囊化效率为 63. 33%；在模拟光照 10 min 后，微胶囊的温度最高达到 64. 8 ℃，相比纯石蜡提升 31. 4 ℃。【结论】 亲水性石墨烯的加入对复合PCMs的光热转换效率有显著提升，具有良好的光热转换及储存性能。

关键词：太阳能；相变材料；微胶囊；石墨烯；石蜡

Abstract

Objective Among the organic phase change materials， paraffin has high thermal and chemical stability， and small volume change during phase transition， non-corrosive and low cost. However， paraffin wax has problems such as poor thermal conductivity and photothermal conversion performance as well as easy leakage during practical use. Phase change microcapsules have good application prospects in thermal management and photothermal conversion. Thermal conductivity and solar absorption efficiency of their shell materials have a significant impact on their application performance. Titanium dioxide （TiO₂）， a semiconductor material， exhibits excellent thermal conductivity and high ultraviolet light absorption efficiency. However， it barely absorbs visible light. The addition of graphene can expand its light absorption range， improving the photothermal conversion efficiency of microcapsules. However， graphene lacks polar groups on its surface， making it difficult to combine with other materials. Although surface modification is commonly used to improve graphene’s surface energy， it often adversely affects the photothermal performance of the microcapsules. To address this， the study uses graphene oxide to exfoliate graphite and prepare hydrophilic graphene. This material retains excellent photothermal properties of graphene， while offering the polar functional groups of graphene oxide， allowing it to integrate effectively with TiO₂.

Methods Graphene oxide has both the excellent photothermal properties of graphene and the polar functional groups of graphene oxide， which are easy to combine well with TiO₂. In this paper， hydrophilic graphene was prepared by liquid-phase exfoliation of expandable graphite using graphene oxide as an additive. Preparation of microcapsules with paraffin as core and TiO₂ as shell using titanium butoxide （TBT） hydrolysis in N，N-Dimethylformamide（DMF） solution . Then hydrophilic graphene was added， and hydrophilic graphene was compounded with TiO₂shell through hydrogen bonding， and paraffin wax was used as the core to prepare to obtain hydrophilic graphene@TiO₂@paraffin composite phase change microcapsules. The properties of the resulting composite phase change microcapsules were systematically studied.

Results and Discussion In the graphene@TiO₂@paraffin composite phase change microcapsules， hydrophilic graphene was closely adsorbed onto the TiO₂shell layer， resulting in spherical microcapsules with an average particle size of 50-150 μm and a rough surface for better dispersion. The optimal sealing performance was achieved when the mass ratio of paraffin wax to titanium butoxide （TBT） was 2∶1， the mass fraction of hydrophilic graphene was 1%， and the leakage was reduced to 6. 90% after 70 min. The microcapsules exhibited good thermal conductivity and latent heat storage. When the hydrophilic graphene mass fraction was 1%， the thermal conductivity of microcapsules was 0. 459 W/（m·K）， the paraffin wax encapsulation rate was 63. 33%， and the enthalpy of phase change was 175. 84 J/g. In addition， the core-shell structure improved the thermal stability of paraffin wax， delaying decomposition and reducing decomposition rate. Photothermal conversion experiments showed that the microcapsules had excellent photothermal conversion and storage ability. The addition of hydrophilic graphene significantly improved the photothermal conversion efficiency of the composite phase change materials （PCMs）， and the graphene@TiO₂@paraffin reached a maximum temperature of 64. 8 ℃ after 10 min of simulated solar irradiation， an increase of 31. 4 ℃ compared to pure paraffin wax.

Conclusion In this paper， hydrophilic graphene is successfully self-assembled onto the surface of TiO₂forming a shell layer for phase change microcapsules. Paraffin， TiO₂ and hydrophilic graphene are only physically bonded to each other. Composite microcapsules have a more uniform spherical structure with rough surface and good dispersibility. The addition of hydrophilic graphene can enhance the thermal conductivity and photothermal conversion performance of PCMs， so that the composite phase change microcapsules have good latent heat storage capacity. The core-shell structure of microcapsules can improve the thermal stability of paraffin waxes， and compared with pure paraffin waxes， the initial thermal decomposition temperature of microcapsules is increased， and the thermal decomposition rate is slower than that of paraffin waxes. The resulting PCMs demonstrate good thermal conductivity， thermal stability， and photothermal performance.

Keywords：solar energy； phase change material； microcapsule； graphene； paraffin wax