JOURNAL OF POROUS MATERIALS
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2019
·Vol. 27
·期 1
·95-105
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IF 1.947
Xu Xiang,Zeng Yanning,Yu Caili,Zhang Faai
A series of mesoporous SBA-15 with various pore diameter (8, 15, 22 and 27 nm) were synthesized and used as “microreactor”. Reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was conducted in the channels of SBA-15 using azodiisobutyronitrile (AIBN) as initiator, ethyl xanthate ethyl propionate as chain transfer agent. The obtained PMMA/SBA-15 composites and neat PMMAs from composites were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption and desorption, Fourier transform infrared spectroscopy, thermogravimetry analysis, differential scanning calorimetry, hydrogen nuclear magnetic resonance. Results showed that compared with PMMA from conventional RAFT polymerization, PMMAs obtained from internal SBA-15 featured with narrower molecule weight distribution (1.34–1.55) and higher thermal stability due to confinement effects. With the increment of pore size of SBA-15, the molecular weight and glass transition temperature (T g ) of PMMA obtained from internal SBA-15 were distinctly improved whereas isotacticity of the PMMA decreased. The properties of the PMMA were managed with controllable RAFT polymerization by regulation the pore size of SBA-15.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
THERMOCHIMICA ACTA
·
2020
·
IF 2.762
Xin Wang,Yongteng Wei,Dongxue Zhang,Xue Lan,Feng Han,Xiao Zheng Lan
The nanoconfinement effect on the phase behaviors of octacosane ( n -C 28 H 58 , C 28 ) was studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In the nanopores of controlled pore glasses (CPGs), silica gels (SGs), SBA-15, and KIT-6, C 28 showed depressed phase transition temperatures. The depression of phase transition temperatures, degree of supercooling and enthalpies of phase transitions for C 28 confined in the CPGs, SGs and SBA-15 exhibited a linear dependence on reverse pore diameter. The phase transition temperatures also varied with the changing pore geometry, and the depression of melting points of C 28 in SBA-15 is about 2 times larger than that in the CPGs and SGs. The interfacial interactions of the pore walls to alkane seem to have a negligible influence on the phase behaviors. The phase transition sequences of the pore-confined C 28 changed largely with the appearance of new R I and R II rotator phases.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2020
·
IF 4.551
Wenli Wei,Peng Liu
Heteroatom doped porous carbon nanotubes (CNTs) have been widely used as sulfur host and stable polysulfide reservoir in the Li–S batteries. In the present work, the effect of the pore size in the porous CNTs on the battery performance of the CNTs-based sulfur cathodes was investigated by comparing the electrochemical performance of the N, O-doped porous CNTs, which were designed by the carbonization of the PPy nanotubes as precursor with different amounts of KOH as activating agent. The results showed that sulfur could completely fill the mesopores and hollow cavity of the mesoporous carbon nanotubes (PNCT-2) prepared with severe KOH activation, with theoretical calculated sulfur content. In comparison with the S -PCNT-1 cathode with sulfur coated onto the outer surface of the microporous carbon nanotubes (PNCT-1), the S -PCNT-2 cathode possessed higher specific capacity and rate capacity, as well as better cyclic life. Such features are ascribed to the large specific surface area and the appropriate pore size of the PCNT-2, which provides an efficient diffusion path for the sulfur and electrolyte as well as polysulfide trap suppressing the “shuttle effect” efficiently.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Lei Hou,Fei Feng,Wenbin You,Pengcheng Xu,Fan Luo,Bowen Tian,Haimei Zhou,Xinxin Li
Microfabricated semi-packed gas chromatography (GC) columns coated with two kinds of mesoporous silica (MS) stationary phase have been explored and compared in this paper. The micro GC (μGC) columns are fabricated by microelectromechanical system (MEMS) technique. MSs with pore size of 2 and 5 nm are prepared using two different soft-templates and deposited on the inner surface of the μGC columns by dip-coating. For the first time, the influence of pore size of MS stationary phase on the separation performance in a μGC column has been investigated. As demonstrated, the mixtures of light alkanes (C1–C4) or heavy alkanes (C5–C10) can be well separated in both columns, where the separation resolution is always higher than 1.25 except for C1–C2 and C5–C6. Considering the pore size effect on the separation performance, it is shown that analytes, especially those with bigger size, display longer retention time in the column with larger pore size. For C10, the retention time in 5 nm-MS column is 200% longer than that in 2 nm-MS one.
研究领域:
分析化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of CO2 Utilization
·
2017
·
IF 4.292
Tianze Xie,Jianyang Wang,Fanshu Ding,Anfeng Zhang,Wenhui Li,Xinwen Guo,Chunshan Song
The effect of support pore size of FeK/Al 2 O 3 catalysts on the catalytic performance in CO 2 hydrogenation reaction was investigated. A total of 8 iron-based catalysts supported on alumina with different pore size were prepared by incipient wetness impregnation where the amount of Fe and K were fixed at 15 and 10 wt%, respectively. N 2 adsorption/desorption, XRD, TPR and PZC were used to characterize the supports and catalysts. The results show that the support pore size impacts the size of Fe 2 O 3 particles formed in the catalyst; increasing pore size of Al 2 O 3 supports led to increased size of Fe 2 O 3 particles formed in the pores. Catalyst pore sizes of 7–10 nm and the corresponding Fe 2 O 3 particle sizes of 5–8 nm were the most active for CO 2 hydrogenation to hydrocarbons. Outside this range, larger pore size further decrease the iron dispersion and reduce the number of active sites; smaller pore size is not favorable on account of the too small Fe 2 O 3 particle sizes and lower reducibility of the small particle.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2013
·
IF 4.814
Xiao Yan,Tong Bo Wang,Chun Feng Gao,Xiao Zheng Lan
Phase behaviors of tridecane–tetradecane (n-C13H28–C14H30, C13–C14) system in bulk, and confined in SBA-15 and controlled porous glass (CPG) are investigated using differential scanning calorimetry and temperature-dependent X-ray diffraction. Bulk C13–C14 mixtures exhibit a complicated behavior featuring a special rotator phase RI. Adsorbed in SBA-15 with pore diameters (d) of 3.8 and 7.8 nm, the binary mixtures display a melting boundary of a straight line and a curve, respectively. Within SBA-15 (17.2 nm) and CPG (8.1, 31.8, 46.4, and 300 nm), the mixtures show a similar phase behavior to the bulk, especially in the larger pore CPG than 30 nm. Under confinement, the phase behavior of C13–C14 mixtures varies with the pore size as well as the temperature and composition. XRD analysis reveals that the solid alkane molecules take effectively the 2D closed-packed arrangements inside pores of diameters less than 20 nm. In the large pore CPG (d > 30 nm), the alkane molecules regain lamellar ordering in solid states. Pore geometries of SBA-15 and CPG, one-dimensional channels vs three-dimensional connected pores, may also result in much different influence on the phase behavior of the confined mixtures.
研究领域:
物理化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2023
·
IF 5.2
Yuhang Liu,Yuanjiang Zhao,Zhuxian Zhou,Youqing Shen,Liming Jiang
In this work the sorption properties of three isoreticular Zr-based MOFs , viz., UiO-66, UiO-67, and UiO-68 as adsorbents of active organics were examined and especially the pore size effects are discussed using d -limonene, myrcene, α-terpinene, and α-pinene as probe molecules. Results indicated that the terpene uptake and release are highly dependent on both the MOF pore size and the geometric feature of guest molecules themselves. The shape selective property of UiO-66 holds for the tested terpenes, where the adsorption capacity of d -limonene, myrcene, and α-terpinene in equilibrium with the liquid phase (0.43–0.46 g g −1 ) was approximately 5-times larger than that of α-pinene with 0.56 nm kinetic diameter (0.09 g g −1 ). The narrow triangular apertures of UiO-66 act as the permeation-limiting barrier for guest molecules with the dimension close to the pore size. Except for α-pinene, the loading fraction for other terpenes decreased with an increase in the MOF pore diameter. For example, the uptake of UiO-66, UiO-67, and UiO-68 for myrcene reached up to 90 %, 81 %, and 76 % of their theoretical maximum loading, respectively. Differential scanning calorimetry revealed that the melting point of both d -limonene and α-terpinene confined in the 0.71 nm pores of UiO-67 shifts to a higher temperature relative to that in the bulk phase. In contrast, no obvious phase transition was observed for the terpene composites with either UiO-66 or UiO-68 (0.94 nm pore size) under identical conditions. Consistent with the thermal analysis results, the monoterpenes entrapped in the UiO-67 showed a much lower release rate than their counterparts in the other two frameworks.
研究领域:
材料科学
·
食品科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）