TY - JOUR
T1 - Methoxy-grafted kaolinite preparation by intercalation of methanol
T2 - Mechanism of its structural variability
AU - Li, Xiaoguang
AU - Cui, Xianjian
AU - Wang, Sen
AU - Wang, Ding
AU - Li, Kuo
AU - Liu, Qinfu
AU - Komarneni, Sridhar
N1 - Funding Information:
The authors gratefully acknowledge the financial support provided by the National Natural Science Foundation of China (No. 51034006), Beijing Nova Program (xx2015B081). This work is supported in part by China Scholarship Council (CSC No.201506430018) during a visit of ‘Xiaoguang Li’ in The Pennsylvania State University, University Park is acknowledged.
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2017/3/1
Y1 - 2017/3/1
N2 - Methoxy-grafted kaolinite is an excellent organic-inorganic compound, which serves as a precursor to prepare new organic or inorganic kaolinite hybrid materials. Direct intercalation of kaolinite with dimethyl sulfoxide (DMSO), N-methylformamide (NMF) and urea (U) was achieved. All of the above intercalated kaolinites could be grafted by methoxy groups by reacting with methanol. The pre-intercalated molecules of DMSO, NMF and U blocked the grafting action at first but facilitated it at a later stage. Here, the mechanism of the structural collapse of methoxy-grafted kaolinite was proposed. Spontaneous deintercalation of small molecules such as water, ethanol, isopropanol and others was observed. Water and methanol molecules played an important role in the grafting action and also affected the structure of methoxy-grafted kaolinite. The d(001) of methoxy-grafted kaolinite was found to be in the range of 0.99–1.11 nm in wet state but constant at 0.86 nm for dry state. 13C CP/MAS NMR analysis confirmed that inner-surface hydroxyls were replaced by methoxy groups from methanol as detected by a 13C MASNMR resonance at 51 ppm assigned to methoxy groups. 13C MASNMR spectra of intercalated kaolinites confirmed that the pre-intercalated molecules were not displaced completely even though it cannot be detected by XRD. The hygroscopicity of the pre-intercalated molecules was found to affect the structure of methoxy-grafted kaolinite.
AB - Methoxy-grafted kaolinite is an excellent organic-inorganic compound, which serves as a precursor to prepare new organic or inorganic kaolinite hybrid materials. Direct intercalation of kaolinite with dimethyl sulfoxide (DMSO), N-methylformamide (NMF) and urea (U) was achieved. All of the above intercalated kaolinites could be grafted by methoxy groups by reacting with methanol. The pre-intercalated molecules of DMSO, NMF and U blocked the grafting action at first but facilitated it at a later stage. Here, the mechanism of the structural collapse of methoxy-grafted kaolinite was proposed. Spontaneous deintercalation of small molecules such as water, ethanol, isopropanol and others was observed. Water and methanol molecules played an important role in the grafting action and also affected the structure of methoxy-grafted kaolinite. The d(001) of methoxy-grafted kaolinite was found to be in the range of 0.99–1.11 nm in wet state but constant at 0.86 nm for dry state. 13C CP/MAS NMR analysis confirmed that inner-surface hydroxyls were replaced by methoxy groups from methanol as detected by a 13C MASNMR resonance at 51 ppm assigned to methoxy groups. 13C MASNMR spectra of intercalated kaolinites confirmed that the pre-intercalated molecules were not displaced completely even though it cannot be detected by XRD. The hygroscopicity of the pre-intercalated molecules was found to affect the structure of methoxy-grafted kaolinite.
UR - http://www.scopus.com/inward/record.url?scp=85008939347&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85008939347&partnerID=8YFLogxK
U2 - 10.1016/j.clay.2016.12.031
DO - 10.1016/j.clay.2016.12.031
M3 - Article
AN - SCOPUS:85008939347
VL - 137
SP - 241
EP - 248
JO - Applied Clay Science
JF - Applied Clay Science
SN - 0169-1317
ER -