Gao Jinling, Li Tongtong, Song Mingzhe, Zhao Yuyao, Wang Anxu
College of Science, Heilongjiang Bayi Agricultural University Daqing 163319 China
RSC Adv. 2022 Aug 22;12(36):23754-23761. doi: 10.1039/d2ra03592h. eCollection 2022 Aug 16.
Dispersible multi-walled carbon nanotubes (MWCNTs) in water have been widely applied in the nanotechnology field. This study reports a water-soluble ,-carboxymethyl chitosan(,-CMCS) assisted individual dispersion of oxidized multi-walled carbon nanotubes (oMWCNTs) as a dispersant. First, the dispersing agent ,-CMCS was successfully synthesized using the nucleophilic substitution of deacetylated chitosan with chloroacetic acid in an alkaline solution. It was further confirmed using Fourier transform infrared spectroscopy (FTIR). Second, after the treatment with the concentrated hydrochloric acid, the prepared oMWCNTs were dispersed in an aqueous solution of ,-CMCS under ultrasonic vibrations. Finally, the dispersed aqueous solution was subjected to centrifugation to collect the supernatant of individually dispersed ,-CMCS/oMWCNTs. In addition, transmission electron microscopy (TEM) further confirmed that the purity of oMWCNTs was improved after the acidification progress. Besides, the stability of the dispersion solution was evidenced by digital photos of oMWCNTs dispersed by ,-CMCS before and after. Moreover, the UV-vis spectrum (the characteristic peak of dispersed oMWCNTs downshifted 13 nm) showed that the supernatant was enriched by the individual oMWCNTs. In particular, the analytical results of FTIR (the -NH band of ,-CMCS downshifted 7 cm), resonance Raman spectroscopy (the / ratio of dispersed oMWCNTs only increased 0.14), and XRD identified the formation of a non-convalent interaction between ,-CMCS and oMWCNTs. These findings reveal the dispersing nature of ,-CMCS towards oMWCNTs in water media.
水中的可分散多壁碳纳米管（MWCNTs）已在纳米技术领域得到广泛应用。本研究报道了一种水溶性的β-羧甲基壳聚糖（β-CMCS）作为分散剂辅助氧化多壁碳纳米管（oMWCNTs）实现单独分散。首先，在碱性溶液中通过脱乙酰壳聚糖与氯乙酸的亲核取代反应成功合成了分散剂β-CMCS，并通过傅里叶变换红外光谱（FTIR）进一步证实。其次，用浓盐酸处理后，将制备的oMWCNTs在超声振动下分散于β-CMCS水溶液中。最后，对分散的水溶液进行离心以收集单独分散的β-CMCS/oMWCNTs的上清液。此外，透射电子显微镜（TEM）进一步证实酸化过程后oMWCNTs的纯度得到提高。此外，通过β-CMCS分散前后oMWCNTs的数码照片证明了分散溶液的稳定性。而且，紫外可见光谱（分散的oMWCNTs的特征峰下移了13 nm）表明上清液中富集了单独的oMWCNTs。特别是，FTIR的分析结果（β-CMCS的-NH谱带下移了7 cm）、共振拉曼光谱（分散的oMWCNTs的I_D/I_G比值仅增加了0.14）以及XRD确定了β-CMCS与oMWCNTs之间形成了非共价相互作用。这些发现揭示了β-CMCS在水介质中对oMWCNTs的分散特性。
