MACROMOLECULES
·
2022
·
IF 6.057
Yu-Pei Tian,Tianyu Wu,Xiaoyu Meng,Hai-Mu Ye
Thermodynamic features of extended-chain crystals (ECCs) are the basis for determining crystallization driving force of polymers. However, accurate determination of melting points (Tm0) and enthalpy of fusion (ΔHm0) of ECCs is still a challenge due to the lack of corresponding physically fabricated structures, especially for a copolymer whose ECC has not been prepared or reported yet. Herein, we choose poly(butylene succinate) (PBS) and its random copolymers with adipic acid (PBSA) as model polymers and successfully fabricate their ECCs through a preparation pathway by forming inclusion complexes with urea. Consequently, the values of Tm0 and ΔHm0 have been directly determined, which are quite different from those extrapolated in previous literature. The Tm0 and ΔHm0 of PBS are respectively identified as 136 °C and 133.5 J/g. With the increase of cocrystallized butylene adipate (BA) units in the lattice, the as-measured Tm0 of the ECC declines more significantly than the extrapolated value by the Hoffman–Weeks equation based on a mismatched crystalline structure. The ΔHm0 of PBSA displays an almost linear downward dependence on BA composition, explicitly revealing a defect Gibbs free energy of 0.7 kJ/mol for the cocrystallization of BA units in PBS lattices. Our work sheds light on the accurate determination of properties of polymer ECCs and is essential to expand the understanding of ECCs from homopolymers to copolymers.
研究领域:
高分子科学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2021
·Vol. 9
·期 27
·15482-15492
·
IF 12.732
Yu Chen,Jin Yang,Lin Zhu,Xiaohua Jia,Sizhe Wang,Yong Li,Haojie Song
Solar-driven water evaporation is an effective approach for using solar energy to purify seawater and wastewater. However, the high energy requirements of bulk water evaporation fundamentally restrict the practicality of solar freshwater production. Herein, we demonstrate an efficient hierarchical solar evaporator by combining polydopamine (PDA) and Ti3C2Tx MXene (MX) with a cellulose network skeleton of delignified wood (DW). By integrating activated water in a hydrated cellulose network and the synergistic photothermal effect between PDA and MX, the obtained PDMX@DW evaporator achieved a high evaporation rate of 2.08 kg m−2 h−1 and energy efficiency of 93.6% under 1 sun illumination. Differential scanning calorimetry and dark evaporation experiments indicated that the water in PDMX@DW exhibited a lower vaporization enthalpy (1915 J g−1) than bulk water (2440 J g−1). Raman spectral analysis and density functional theory calculations were used to investigate the structure of water molecules in the cellulose network, and it turns out that high contents of weakly hydrogen-bonded intermediate water were the most likely origin of the reduced vaporization enthalpy. More importantly, due to the interactive cellulose network structure and increased water supply rate, PDMX@DW exhibited excellent salt resistance and long-term stability in high-concentration brine. This work provides an effective method for breaking the evaporation limitation of the traditional wood-based evaporator and improving its salt resistance.
研究领域:
材料科学
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能源工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2021
·
IF 2.694
JinTao He,XueMan Xu,Xia Gui
New phase equilibrium data of CO2 in n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane were measured at temperatures from 333.15 to 373.15 K up to 23.73 MPa by a constant-volume method. Thermodynamic properties of Gibbs free energy (ΔsolG), enthalpy change (ΔsolH), entropy change (ΔsolS), and Henry’s coefficient (H) were calculated and analyzed for elucidating the dissolution mechanism of CO2 in alkanes. Results showed that the CO2 solubility increased with increasing pressure but decreased with increasing temperature and carbon number. In addition, increasing carbon number also led to an increase in the minimum miscibility pressure (MMP) of alkanes with CO2 and thus limited CO2 solubility in alkanes.
研究领域:
化学热力学
·
石油工程
✓ 已验证
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2014
·
IF 5.03
Chun-Feng Gao,Li-Ping Wang,Qi-Feng Li,Chao Wang,Zhao-Dong Nan,Xiao-Zheng Lan
In practical use, latent heat storage system always faces a lack of phase change materials (PCMs) that have ideal performance at desirable temperature and high efficiency to treat thermal effects from various outer heat sources. To solve this problem, some new latent heat storage composites were prepared by incorporating those well-performed PCMs in porous materials. In doing this, the layered perovskite-type compounds, (1-C 10 H 21 NH 3 ) 2 ZnCl 4 (C 10 Zn) and (1-C 12 H 25 NH 3 ) 2 ZnCl 4 (C 12 Zn), were embedded in controlled porous glass (CPG), which can acquire size-dependent thermal properties. Heat storage nature, morphology and crystalline structures of the materials were characterized using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and powder X-ray diffractions (XRD). Under confinement of the porous glass with nominal pore sizes of d =12–300 nm, the porous C n Zn compound gains a regulation window of around 10 °C in relation to the bulk by its solid–solid phase transition. The transition temperature ( T d ), depression of the transition temperature (∆ T trs ), and enthalpy change of the transition (∆ trs H d ) of the confined compound show a linear relation to the reverse pore size. A same stable thermal cycling property is observed in the pore compound as the bulk, which is consistent with similar diffraction patterns among them. The supercooling of the pore form becomes larger than the bulk. The retention of the layered structure and complete crystallization in the pore C n Zn is responsible for its reversible heat storage property.
研究领域:
材料科学
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热能工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
2021
·
IF 3.196
Simin Liu,Defei Yin,Wei Li,Dongzhi Liu,Xueqin Zhou
In this paper, three new compounds were synthesized by introduction of benzyloxy group to phenylethyl phenylacetate ( PPA ) and shorting the flexible ester linker. NMR spectra and mass spectra are achieved to confirm the structure of the compounds. The solid-liquid and liquid-solid phase change behaviors of PPA and these three compounds were explored by direct observation and differential scanning calorimetry (DSC) measurements. It was found that all four compounds would form supercooled liquids during a heating-cooling cycle. The supercooling degree is as large as 44 °C or above. The effects of benzyloxy group and the flexible linker on the phase transition processes as well as the supercooling degrees were discussed in detail with the computational optimized geometry of isolated molecules. It was revealed that the dihedral angles between adjacent phenyl rings play a significant role in tuning their phase transition temperatures. This work also discovers the high enthalpies of PPA derivatives and analogues in both solid-liquid and liquid-solid phase transition processes, making them great potentials for the thermal energy control of appropriate working temperature regions.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2016
·
IF 2.196
Yaotai Jiang,Xiaobang Liu,Dongshun Deng
The solubilities of SO 2 in three dipolar aprotic urea diversities, 1,1,3,3-tetramethylurea (TMU), 1,3-dimethyl-2-imidazolidinone (DMI), and 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H)-pyrimidinone (DMPU) was measured at temperatures ranging from (293.15 to 323.15) K and pressure up to 120 kPa. By correlating the solubility results with a reaction equilibrium thermodynamic model (RETM), Henry’s constants ( H m ), reaction equilibrium constants ( K °), and enthalpy (Δ H r ) in the absorption process were obtained. The results indicate that the three solvents exhibit both strong physical and weak chemical interactions with SO 2 . Further comparison of the capture performance with ILs, deep eutectic solvents (DESs), and several organic solvents, DMI, DMPU and TMU are noted to be excellent absorbents for acidic SO 2 .
研究领域:
化学工程
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2014
·
IF 2.423
Yujie Wang,Pengxiao Lou,Guangyue Bai,Caoying Fan,Margarida Bastos
The thermodynamics of the process of self-assembly of cationic gemini surfactants, [C 12 H 25 (CH 3 ) 2 N(CH 2 ) S N(CH 3 ) 2 C 12 H 25 ]Br 2 , (the spacer S being 2, 6 or 10, assigned as C 12 C S C 12 Br 2 ) and the system of oppositely charged mixture of surfactants formed by C 12 C S C 12 Br 2 and sodium cholate (NaCA) in aqueous solution has been investigated by isothermal titration calorimetry (ITC), conductivity and turbidity measurements. The critical micelle concentration values (cmc) for the gemini surfactants C 12 C S C 12 Br 2 obtained from calorimetry and conductivity were found to be consistent with values reported in the literature. The enthalpies of micellization (Δ H mic ) of C 12 C S C 12 Br 2 are all exothermic, presenting a strong negative minimum at S = 6, corresponding to the maximum in the cmc values. For the mixed system of oppositely charged surfactants (C 12 C S C 12 Br 2 ( S = 2, 6, 10)/NaCA), we did obtain from ITC the critical parameters for different events that take place as the concentration of gemini surfactant increases, such as the formation of NaCA-rich mixed micelles (cmc mix , Δ H mic-mix ), the formation of a precipitate (immiscible liquid crystalline (LC) phase) ( C P , Δ H P ) and its re-dissolution ( C R , Δ H R ), and finally the formation of positive charge-rich mixed micelles ( C M , Δ H M ). It should be stressed that the values of cmc mix (gemini) are much smaller than those for pure gemini and pure NaCA. These results also show that there is a stronger synergistic effect between the two surfactants in the NaCA-rich region. The turbidity measurements proved valuable to the determination of the region of immiscible LC phase. The ITC results are combined with those obtained by conductivity and turbidity leading to a thorough discussion of the effect of the gemini spacer length on the aggregation behavior of the mixed systems.
研究领域:
物理化学
·
胶体与界面科学
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产品关联
DOI
高影响因子
JOURNAL OF SOLUTION CHEMISTRY
·
2018
·Vol. 47
·期 4
·705-714
·
IF 1.401
Li Qiang,Liu Bijun,Mu Wanjun,Yu Qianhong,Tian Yin,Liu Guoping,Yang Yuchuan,Li Xingliang,Luo Shunzhong
Glufosinate, an analogue of glutamic acid (also known as phosphinothricin), is an important herbicide. The protonation constants of glufosinate were determined by means of potentiometric titrations at variable temperatures with ionic strength 0.5 mol·L −1 (NaCl solution). The heat effects of the protonation reactions of glufosinate were measured by direct calorimetry. NMR spectroscopies have demonstrated that the first protonation site occurs on the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and crystal structure results. These data will help to predict the speciation of glufosinate in physiological systems.
研究领域:
植物学
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化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2021
·
IF 4.539
Jinghang Wang,Xinyu Zhai,Zunrui Zhong,Xinwen Zhang,Hao Peng
A series of nanoencapsulated phase change materials with n-tetradecane as the core material and melamine–urea–formaldehyde (MUF)–TiO 2 composite as the shell material was developed using a two-step method. Sol-gel and blending modification methods were respectively utilized after the in situ polymerization. The physical, chemical, and thermal properties of the nanoencapsulated phase change material (NEPCM) samples were characterized. Furthermore, a comprehensive performance evaluation system was established based on the efficacy coefficient method. The results indicated that the average diameter of the nanocapsules was significantly increased by the sol-gel modification and was slightly influenced by the blending method. All NEPCMs exhibited high chemical and thermal stability. The NEPCMs modified by the sol-gel method (C 14 @MUF–TiO 2 -S1) exhibited the best performance in terms of the encapsulation ratio, melting enthalpy , and onset decomposition temperature , which were 68.6%, 156.2 J·g -1 , and 155.36 °C, respectively. C 14 @MUF–TiO 2 -S2 exhibited the lowest mass loss of 44.2% at 100 h. For the blending method, C 14 @MUF–TiO 2 -B1 had the highest yield of 53.87%. The thermal conductivity of C 14 @MUF–TiO 2 -B3 increased up to 88.15% compared with the unmodified NEPCMs. Therefore, modification by the sol-gel method with 2.2 g TiO 2 sol had the highest total efficacy coefficient of 0.843 among the samples.
研究领域:
材料科学
·
能源存储
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2014
·
IF 2.423
Da-Shun Zhang,Zhi-Cheng Tan,Bei-Ping Liu,Xiao-Bing Huang
Neodymium complex with glycine, Nd(Gly) 2 Cl 3 ·3H 2 O, was synthesized and characterized by IR spectra. The thermal stability of the complex was tested through TG and DTG and a possible mechanism of thermal decomposition was proposed. The heat capacities of the complex were measured by using an automated adiabatic calorimeter over the temperature range from T = (80 to 380) K, the thermodynamic functions, [ H T − H 298.15 ] and [ S T − S 298.15 ], were calculated based on the heat capacity measurements. Two (solid + solid) phase transitions in the ranges of T = (170 to 247) K were observed with the peak temperatures of 184.896 K and 231.217, respectively. The standard molar enthalpy of formation of [Nd(Gly) 2 Cl 3 ·3H 2 O] was determined to be (−3081.3 ± 1.1) kJ · mol −1 in terms of an isoperibol solution-reaction calorimeter.
研究领域:
物理化学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 101
·99361-99366
·
IF 3.289
Lan Lei,Lin Feng,Binglei Song,Zhaolan Zhai,Shibin Shang,Zhanqian Song
Modification of the molecular structures of surfactants is a feasible way to construct ionic liquid crystals (ILCs) with novel properties. Five quaternary ammonium gemini surfactants with different spacers, whose head groups were substituted by four hydroxyethyl groups, abbreviated as 12(2OH)-s-12-(2OH) (s = 3, 4, 5, 6, 8), were prepared. The mesomorphic behaviors of these gemini surfactants were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and temperature-dependent FT-IR spectroscopy. These surfactants form smectic A (SmA) phases, the region of which is dependent on the spacer length. The presence of suitable spacer length and multiple hydroxyl groups is helpful in stabilizing the mesophases. Noticeably, because of synergistic effect of the spacer and the hydroxyl groups, the phase enthalpy change of SmA to crystal transitions can be slowly released below the phase transition temperature. This interesting discovery, which has never been reported in ILC systems formed by small molecular weight surfactants, could pave the way for special applications of ILCs in the area of sustained-release materials of heat and could widen the application of ionic liquid crystals.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2018
·Vol. 135
·期 6
·3363-3373
·
IF 2.209
Zhang Shijie,Zhang Jiaoqiang,Kou Kaichang,Jia Qian,Xu Yunlong,Zerraza Sofiane,Liu Ning,Hu Rongzu
2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexazisowurtzitane (HNIW)·1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) co-crystal in a 2:1 molar ratio was prepared by a solvent/non-solvent method, and the co-crystal has been characterized by several methods. The enthalpies of dissolution of 2HNIW·HMX co-crystal in N,N -dimethylformamide at different temperatures were measured by a DC08-1 Calvet microcalorimeter under standard atmospheric pressure, and it is indicated that the dissolutions are exothermic process. The empirical formulae for the calculation of the molar enthalpy ( \(\Delta_{\text{diss}} H\) ) of dissolution, relative partial molar enthalpy ( \(\Delta_{\text{diss}} H_{\text{partial}}\) ), relative apparent molar enthalpy ( \(\Delta_{\text{diss}} H_{\text{apparent}}\) ), and enthalpy of dilution ( \(\Delta_{\text{dil}} H_{1,2}\) ) at 298.15 K are obtained. The differential enthalpies ( \(\Delta_{\text{dif}} H\) ) and kinetic equations describing the dissolution process at different temperatures are deduced. Furthermore, the apparent activation energy E = 10.54 ± 0.22 kJ mol -1 and pre-exponential constant A = 0.34 ± 0.03 s −1 of 2HNIW·HMX co-crystal are obtained. The standard molar Gibbs free energy of activation ( \(\Delta G_{ \ne }^{\theta }\) ) at different temperatures is 86.44 ± 0.02 kJ mol −1 (298.15 K), 88.02 ± 0.03 kJ mol −1 (303.15 K), 89.61 ± 0.01 kJ mol −1 (308.15 K), 91.18 ± 0.01 kJ mol −1 (313.15 K), and 92.75 ± 0.02 kJ mol −1 (318.15 K), respectively. The standard molar entropy of activation ( \(\Delta S_{ \ne }^{\theta }\) ) and standard molar enthalpy of activation ( \(\Delta H_{ \ne }^{\theta }\) ) are − 262.55 ± 0.72 J mol −1 K −1 and 7.98 ± 0.22 kJ mol −1 , respectively.
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
危险品化学品经营许可证（带存储）