摘要
Pickering乳液固含量和储存稳定性等性能显著优于传统乳液,但是,其乳化剂品种仍然稀缺,以苯乙烯(St)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为主要单体,二乙烯基苯(DVB)为交联剂,乙醇为助溶剂,用无皂乳液聚合法制备了阳离子型共聚物颗粒(P(St-co-DMC)),并将其作为乳化剂制备了石蜡Pickering乳液;并将石蜡乳液浸渍粘胶水刺非织造布制备石蜡微胶囊相变材料(Vis-PCM)。借助红外光谱仪、扫描电子显微镜、热重/差热联用仪、差示扫描量热仪和接触角测量仪等对共聚物及相变材料微观结构与性能进行表征与测试。实验结果表明:随着DMC用量、引发剂用量和乙醇含量的增加,单体转化率先增大后减小,P(St-co-DMC)粒径和分散指数先减小后增大,其Zeta电位则先快速增大而后趋于恒定,而亲水性持续增强;所得石蜡Pickering乳液的油水体积比高达3∶1,储存稳定性超过3个月;Vis-PCM的相变潜热高达139.3 J/g,经过20次冷热循环处理后,Vis-PCM中的石蜡泄漏率仅0.6%。本文制备的Vis-PCM具有良好的储热与放热性能,在相变储能领域具有广阔的应用前景。
Objective Pickering emulsion uses solid-particles as emulsifier instead of small-molecule surfactants,in which solid particles are embedded on the surface of emulsion droplets,and thus its interfacial adsorption energy is far greater than the thermodynamic energy of the solid particle Brown motion.Consequently,it is difficult for the solid particles to escape from the oil-water interface,providing the emulsion with excellent storage stability.Pickering solid emulsifier in the paraffin emulsion does not cut down the paraffin crystalline temperature,and eliminates the subcool phenomenon,and improves its phase-change energy storage performance.Unfortunately,very few Pickering emulsifiers have existed,such as nano-silica,graphene oxide,nano-cellulose crystals,more often being applied with organic polymer co-emulsifier.Methods Soap-free emulsion polymerization was carried out with styrene(St)and methacryloxyethyl-trimethylammonium chloride(DMC)as monomers,divinyl benzene(DVB)as crosslinker,ethanol as auxiliary solvent.Cationic copolymer particles characterized with monodispersity,clean surface,and designed size were obtained.The paraffin Pickering emulsions and paraffin droplets on viscose fabric phase change materials(Vis-PCM)were prepared by using the resultant copolymer nanoparticles(P(St-co-DMC)).The microstructure and properties,monomer conversion,nanoparticle size,Zeta potential and contact angles of P(St-co-DMC)particles as well as Vis-PCM were investigate d by Fourier transform infrared spectrometry,scanning electron microscopy,thermogravimetry,differential scanning calorimetry,and contact angle goniometry.Results The influences of DMC and initiator dosages,and ethanol contents on the monomer conversion and the nanoparticle size,as well as of DMC dosages on the contact angle and Zeta potential of the nanoparticles were studied.The results showed that cationic P(St-co-DMC)copolymer nanoparticles were successfully prepared,and the two major monomers were merged into the copolymer chain.The resulted polymers were shown to withstand the thermal shock during emulsification process,as well as phase change energy storage and heat release recycling processes.The monomer conversion presented bell-shape behavior,whereas the particle size and its dispersion index showed reversed bell tendency with the increases of DMC,initiator and ethanol.However,the Zeta potential of the copolymer particles initially soared up and then tended to be constant,whereas the hydrophilicity was improved with the increase of DMC dosage.When the amounts of DMC,KPS and ethanol were fixed at 25%,2.5%and 15%,respectively,the monomer conversion reached 83%,the size,the Zeta potential,and the surface contact angle of the resultant copolymer particles were 114 nm,47.2 mV,and 58°,respectively.The over three-month shelf life,oil-in-water paraffin Pickering emulsion at the oil-to-water volume ratio of 3∶1 and at the droplet size of(4.4±0.5)μm was eventually obtained.The phase change latent heat of Vis-PCM,which was obtained by impregnating spunlaced viscose nonwoven fabric into the Pickering emulsion,reached up to 139.3 J/g,and the paraffin leakage rate of Vis-PCM was only 0.6%after 20 thermal cycls.Conclusion Copolymer particles with controllable surface features such as water contact angle,particle size and electricity,instead of the small molecule surfactant,can be adsorbed firmly at the oil-water interface to obtain a long shelf life Pickering emulsion.P(St-co-DMC)emulsifier copes with the paraffin subcool phenomenon due to small molecule surfactant plasticizer based on heterogeneous nucleation mechanism.Also it is emulsion droplets rather than de-emulsified paraffin bulk that adhere to the nonwoven surface,which ensures the paraffin-microencapsulated fabric acting as reusable phase change energy storage materials.All the results confirm that P(St-co-DMC)possesses excellent emulsifying ability,and Vis-PCM has good heat storage and heat release properties.
作者
柯文涛
陈明
郑淳天
石小丽
朱新生
KE Wentao;CHEN Ming;ZHENG Chuntian;SHI Xiaoli;ZHU Xinsheng(College of Textile and Clothing Engineering,Soochow University,Suzhou,Jiangsu 215021,China;College of Chemistry,Chemical Engineering and Materials Science,Soochow University,Suzhou,Jiangsu 215223,China)
出处
《纺织学报》
EI
CAS
CSCD
北大核心
2024年第7期130-139,共10页
Journal of Textile Research
