1
|
Zhang X, Wei F, Wang Z, Li G, Yang S, Feng J. Comparative investigation of the structural evolution of zinc stearate and calcium stearate in a polypropylene random copolymer upon heating and cooling. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
2
|
Hao LS, Yuan C, Zhong HL, Ling JW, Wang HX, Nan YQ. Triple-Stimuli-Responsive Hydrogels Based on an Aqueous Mixed Sodium Stearate and Cetyltrimethylammonium Bromide System. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
3
|
Barannikov R, Kočí E, Bezdička P, Kobera L, Mahun A, Rohlíček J, Plocek J, Švarcová S. Long-chain mercury carboxylates relevant to saponification in oil and tempera paintings: XRPD and ssNMR complementary study of their crystal structures. Dalton Trans 2022; 51:4019-4032. [PMID: 35174830 DOI: 10.1039/d1dt04160f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Saponification, resulting from pigment-binder interactions, is one of the most endangering phenomena affecting the appearance and stability of painted works of art. The crystallization of metal carboxylates (soaps) in paint layers is recently assumed as the most critical point for the development of undesirable changes induced by saponification, however, the factors triggering it are not fully understood. The red pigment cinnabar (HgS) has been suspected of contributing to saponification, however, the paucity of reliable reference structural data limited the experimental research of its effect at the molecular level. Within this study we synthesized mercury(II) carboxylates of the formula Hg(C16)x(C18)2-x (x = 0.0; 0.2; 0.5; 0.8; 1.0; 1.2; 1.5; 1.8; 2.0) where C16 and C18 are hexadecanoate (palmitate) and octadecanoate (stearate), respectively, and characterize them by combination of X-ray powder diffraction (XRPD) and 13C and 199Hg solid state NMR (ssNMR). For a more detailed interpretation of their structural and thermal behavior, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used. The crystal structure of the studied mercury carboxylates was described on the basis of complementary ssNMR and XRPD measurements, Rietveld refinement and DFT calculations. All the subjected compounds crystallize in a monoclinic lattice of the C2/c symmetry. Mercury atoms are arranged in a slightly distorted square antiprismatic geometry and are monodentatically bonded to carboxylate anions. The structural disorder at the aliphatic end of the stearic acid chains was detected in the mixed carboxylates. Within the paper, the structural (dis)similarity with the corresponding lead carboxylates is discussed. The synthesized and characterized mercury carboxylates were applied to describe neo-formed mercury soaps in a model experiment simulating an egg-based paint system.
Collapse
Affiliation(s)
- Ruslan Barannikov
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, ALMA Laboratory, Husinec-Řež 1001, 250 68 Husinec-Řež, Czech Republic. .,Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 128 43 Prague 2, Czech Republic.
| | - Eva Kočí
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, ALMA Laboratory, Husinec-Řež 1001, 250 68 Husinec-Řež, Czech Republic.
| | - Petr Bezdička
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, ALMA Laboratory, Husinec-Řež 1001, 250 68 Husinec-Řež, Czech Republic.
| | - Libor Kobera
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Praha 6, Czech Republic.
| | - Andrii Mahun
- Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, 162 06 Praha 6, Czech Republic. .,Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 40, Prague 2, Czech Republic.
| | - Jan Rohlíček
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Praha 8, Czech Republic.
| | - Jiří Plocek
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, ALMA Laboratory, Husinec-Řež 1001, 250 68 Husinec-Řež, Czech Republic.
| | - Silvie Švarcová
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, ALMA Laboratory, Husinec-Řež 1001, 250 68 Husinec-Řež, Czech Republic.
| |
Collapse
|
4
|
Melchiorre M, Cucciolito ME, Di Serio M, Ruffo F, Tarallo O, Trifuoggi M, Esposito R. Homogeneous Catalysis and Heterogeneous Recycling: A Simple Zn(II) Catalyst for Green Fatty Acid Esterification. ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2021; 9:6001-6011. [PMID: 34306834 PMCID: PMC8297397 DOI: 10.1021/acssuschemeng.1c01140] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/19/2021] [Indexed: 05/17/2023]
Abstract
This work describes the use of simple zinc(II) salts (ZnCl2, ZnCO3, Zn(OAc)2, ZnO, Zn(ClO4)2, Zn(TfO)2, and Zn(BF4)2) as effective catalysts for the esterification of fatty acids with long-chain alcohols and simple polyols through a homogeneous system that allows the gradual and selective removal of water. The results show that the catalytic activity depends on the nature of the counterion: the most effective are the salts with poorly coordinating anions (perchlorate and triflate) or containing basic Brønsted anions (oxide, acetate, and carbonate). However, only with the latter is it possible to fully recover the catalyst at the end of each run, which is easily filtered in the form of zinc carboxylate, given its insolubility in the ester produced. In this way, it is possible to recycle the catalyst numerous times, without any loss of activity. This beneficial prerogative couples the efficiency of the homogeneous catalysis with the advantage of the heterogeneous catalysis. The process is, therefore, truly sustainable, given its high efficiency, low energy consumption, ease of purification, and the absence of auxiliary substances and byproducts.
Collapse
Affiliation(s)
| | - Maria Elena Cucciolito
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via
Cintia 21, 80126 Napoli, Italy
- Consorzio
Interuniversitario di Reattività Chimica e Catalisi, Via Celso Ulpiani 27, 70126 Bari, Italy
| | - Martino Di Serio
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via
Cintia 21, 80126 Napoli, Italy
- Consorzio
Interuniversitario di Reattività Chimica e Catalisi, Via Celso Ulpiani 27, 70126 Bari, Italy
| | - Francesco Ruffo
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via
Cintia 21, 80126 Napoli, Italy
- Consorzio
Interuniversitario di Reattività Chimica e Catalisi, Via Celso Ulpiani 27, 70126 Bari, Italy
| | - Oreste Tarallo
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via
Cintia 21, 80126 Napoli, Italy
| | - Marco Trifuoggi
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via
Cintia 21, 80126 Napoli, Italy
| | - Roberto Esposito
- Dipartimento
di Scienze Chimiche, Università di
Napoli Federico II, Via
Cintia 21, 80126 Napoli, Italy
- Consorzio
Interuniversitario di Reattività Chimica e Catalisi, Via Celso Ulpiani 27, 70126 Bari, Italy
| |
Collapse
|
5
|
Synthesis of Fatty Acid Methyl Esters from Pomace Oil Catalyzed by Zinc Stearate: A Kinetic Study of the Transesterification and Esterification Reactions. Catalysts 2019. [DOI: 10.3390/catal9120978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In this work, the simultaneous transesterification and esterification reactions of olive pomace oil with methanol catalyzed by zinc stearate were studied. This catalyst is a crystalline solid at room temperature, but it is soluble in the reaction medium at reaction temperature. Zinc stearate has surfactant properties that cause the formation of an emulsion in the reaction system. The stability of the emulsion formed in the oil–methanol–catalyst system was compared to that in the FAME (fatty acid methyl esters)–methanol–catalyst system. It was observed that the emulsion formed in the presence of high amounts of FAME is much more unstable, which makes the catalyst easy to separate from the reaction products. The kinetics of esterification and transesterification were also studied. All the kinetic and equilibrium constants were determined with a complete model, considering the three stepwise reactions corresponding to the transesterification of triglycerides and the esterification of free fatty acids. The parameters obtained were used to model the operating conditions that would allow obtaining biodiesel that meets the quality standards.
Collapse
|
6
|
Park KS, Kim YJ, Choe EK. Composition Characterization of Fatty Acid Zinc Salts by Chromatographic and NMR Spectroscopic Analyses on Their Fatty Acid Methyl Esters. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2019; 2019:7594767. [PMID: 31929937 PMCID: PMC6942835 DOI: 10.1155/2019/7594767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 11/20/2019] [Accepted: 12/03/2019] [Indexed: 05/20/2023]
Abstract
To implement EU REACH- (Registration, Evaluation, and Authorization of Chemicals-) like chemical legislations in various countries of which the purpose is human and environment safety, the first step is substance identification followed by the hazard and risk assessments. Although both structural and composition identifications are required, the latter can more importantly result in the essential data to fill out the required substance information such as purity and concentrations of constituents, as well as impurities. With fatty acid zinc salts (FAZSs) as an exemplary industrial chemical of which chromatographic and nuclear magnetic resonance (NMR) analyses were impossible due to their insolubility in water and any organic solvents, the composition characterization was tried by preparing their fatty acid methyl esters (FAMEs) using the conc. HCl/methanol/toluene method. This acid-catalyzed methyl esterification was optimized with zinc stearate as a surrogate substance. Gas chromatography-mass spectrometry (GC-MS) and NMR analyses on methyl-esterified products revealed that the optimum conditions were at 90°C for 10 min or 45°C for 30 min with two equivalent HCl as well as at 45°C for 10 min with five equivalent HCl. Almost all zinc stearates were converted into the corresponding fatty acids with 97-99% conversion rates. Free fatty acids (FFAs) were detected in extracted ion chromatograms of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) in the methyl-esterified products with incomplete conversions of 73∼79%. The optimized conc. HCl/methanol/toluene method of direct one-step reaction from FAZSs was compared with the two-step NaOH saponification/BF3-methanol method after acidic hydrolysis of FAZSs. The mechanism of fatty acid zinc salts into free fatty acids and fatty acid methyl esters was suggested with the evidence of the formation of Zn(OH)2.
Collapse
Affiliation(s)
- Kwang Seo Park
- Regulatory Chemical Analysis Laboratory, Korea Institute of Industrial Technology, Ansan 15588, Republic of Korea
| | - Yun Ju Kim
- Regulatory Chemical Analysis Laboratory, Korea Institute of Industrial Technology, Ansan 15588, Republic of Korea
| | - Eun Kyung Choe
- Regulatory Chemical Analysis Laboratory, Korea Institute of Industrial Technology, Ansan 15588, Republic of Korea
| |
Collapse
|
7
|
Huang Z, Qi P, Liu Y, Chai C, Wang Y, Song A, Hao J. Ionic-surfactants-based thermotropic liquid crystals. Phys Chem Chem Phys 2019; 21:15256-15281. [DOI: 10.1039/c9cp02697e] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ionic surfactants can be combined with various functional groups through electrostatic interaction, resulting in a series of thermotropic liquid crystals (TLCs).
Collapse
Affiliation(s)
- Zhaohui Huang
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Ping Qi
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Yihan Liu
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Chunxiao Chai
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Yitong Wang
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Aixin Song
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| | - Jingcheng Hao
- Key Laboratory of Colloid and Interface Chemistry
- Shandong University
- Ministry of Education
- Jinan
- China
| |
Collapse
|
8
|
Maruyama SA, Zawadzki SF, Wypych F. Synthesis of Layered Disodium (or Dipotassium) Tetrakis-(octanoate-o)-Zinc(II) and Preliminary Investigation of the Catalytic Activity in the Esterification of Octanoic Acid with Isopropanol. KINETICS AND CATALYSIS 2018. [DOI: 10.1134/s0023158417060076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
9
|
Tavares SR, Wypych F, Leitão AA. DFT-based calculations of the adsorptions of acetic acid, triacetin, methanol and the alkoxide formation on the surfaces of zinc acetate. MOLECULAR CATALYSIS 2017. [DOI: 10.1016/j.mcat.2017.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
10
|
Yamamoto Y, Morikawa T, Kawai T, Nonomura Y. Selective Bactericidal Activity of Divalent Metal Salts of Lauric Acid. ACS OMEGA 2017; 2:113-121. [PMID: 30023510 PMCID: PMC6044674 DOI: 10.1021/acsomega.6b00279] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/27/2016] [Indexed: 05/10/2023]
Abstract
Bacteria play a crucial role in skin health. For example, Staphylococcus aureus and Propionibacterium acnes cause skin roughness and acne, whereas Staphylococcus epidermidis enhances innate barrier immunity. Therefore, controlling the bacterial flora is important in dermatology and cosmetic chemistry. In this study, the bactericidal activities of different metal salts of lauric acid were evaluated. The bactericidal behavior of the salts changed according to the type of metal ion. Specifically, the Mg-, Ca-, and Mn-containing salts effectively sterilized only S. aureus and P. acnes. Their Co, Ni, and Cu salts sterilized all bacteria, including S. epidermidis, whereas the Zn salt proved ineffective. The Cu salt displayed the strongest bactericidal activity. Spin-trapping, detected using electron spin resonance, showed that this salt catalyzed the generation of hydroxyl radicals, which can destroy bacterial cell membranes. These findings demonstrate that metal-ion selection is an important factor in the design of bactericidal agents for healthcare products.
Collapse
Affiliation(s)
- Yoshiaki Yamamoto
- Department
of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan
| | - Toshiya Morikawa
- Skin-Care
Laboratories, Kao Corporation, CRIS Building, 2-1-3, Bunka, Sumida-ku, Tokyo 131-8501, Japan
| | - Takahiro Kawai
- Department
of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan
| | - Yoshimune Nonomura
- Department
of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan
- E-mail: .
Tel: +81-238-26-3164. Fax: +81-238-26-3406
| |
Collapse
|
11
|
Hermans JJ, Keune K, van Loon A, Iedema PD. The crystallization of metal soaps and fatty acids in oil paint model systems. Phys Chem Chem Phys 2017; 18:10896-905. [PMID: 27039879 DOI: 10.1039/c6cp00487c] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation and crystallization of metal soaps in oil paint layers is an important issue in the conservation of oil paintings. The chemical reactions and physical processes that are involved in releasing metal ions from pigments and fatty acids from the oil binder to form crystalline metal soap deposits have so far remained poorly understood. We have used a combination of differential scanning calorimetry (DSC) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) on model mixtures of palmitic acid, lead palmitate or zinc palmitate and linseed oil to study the transition from amorphous material to crystalline fatty acid or metal soap. This transition forms the final stage in the cascade of processes leading to metal soap-related oil paint degradation. Palmitic acid as well as the metal soaps showed nearly ideal solubility behavior. However, it was found that, near room temperature, both lead and zinc palmitate are practically insoluble in both liquid and partially polymerized linseed oil. Interestingly, the rate of metal soap and fatty acid crystallization decreased rapidly with the degree of linseed oil polymerization, possibly leading to systems where metal soaps are kinetically trapped in a semi-crystalline state. To explain the various morphologies of metal soap aggregates observed in oil paint layers, it is proposed that factors affecting the probability of crystal nucleation and the rate of crystal growth play a crucial role, like exposure to heat or cleaning solvents and the presence of microcracks.
Collapse
Affiliation(s)
- Joen J Hermans
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090GD Amsterdam, The Netherlands.
| | - Katrien Keune
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090GD Amsterdam, The Netherlands. and Rijksmuseum Amsterdam, Conservation and Restoration, PO box 74888, 1070DN Amsterdam, The Netherlands
| | - Annelies van Loon
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090GD Amsterdam, The Netherlands.
| | - Piet D Iedema
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO box 94157, 1090GD Amsterdam, The Netherlands.
| |
Collapse
|
12
|
Tavares SR, Wypych F, Leitão AA. A theoretical study of a homologous series of zinc n-alkanoates (2 ≤ n ≤ 8): Structural analysis, evaluation of their interactions and monofilm formation. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.07.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
13
|
Ikeda Y, Yasuda Y, Ohashi T, Yokohama H, Minoda S, Kobayashi H, Honma T. Dinuclear Bridging Bidentate Zinc/Stearate Complex in Sulfur Cross-Linking of Rubber. Macromolecules 2015. [DOI: 10.1021/ma502063m] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Yuko Ikeda
- Graduate
School of Science and Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
| | - Yoritaka Yasuda
- Graduate
School of Science and Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
| | - Takumi Ohashi
- Graduate
School of Science and Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
| | - Hiroyuki Yokohama
- Graduate
School of Science and Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
| | - Shinya Minoda
- Graduate
School of Science and Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
| | - Hisayoshi Kobayashi
- Graduate
School of Science and Technology, Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
| | - Tetsuo Honma
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| |
Collapse
|
14
|
Beltran V, Salvadó N, Butí S, Cinque G. Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks. Microchem J 2015. [DOI: 10.1016/j.microc.2014.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
15
|
The molecular structure of three types of long-chain zinc(II) alkanoates for the study of oil paint degradation. Polyhedron 2014. [DOI: 10.1016/j.poly.2014.06.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
16
|
Reinoso DM, Ferreira ML, Tonetto GM. Study of the reaction mechanism of the transesterification of triglycerides catalyzed by zinc carboxylates. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.molcata.2013.04.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
17
|
de Pauli M, Magalhães-Paniago R, Malachias A. Phase-dependent premelting of self-assembled phosphonic acid multilayers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:052402. [PMID: 23767549 DOI: 10.1103/physreve.87.052402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/10/2013] [Indexed: 06/02/2023]
Abstract
Melting and premelting phenomena in self-organized organic systems have been extensively explored in the literature, exploring distinct behaviors of different molecule lengths and morphologies. Nevertheless, the influence of the supramolecular assembly configuration on the occurrence of premelting remains poorly explored. Here we use phosphonic acids as model systems for self-organized molecular assemblies. These molecules exhibit long-range order on different types of substrates. The balance between chain-to-chain and head-to-head interactions leads to distinct types of stackings. Although their structural configurations are well understood, very little is known about their behavior near the melting transition. We show here that premelting occurs in lamellar structures and that its behavior depends directly on the ordered configuration assumed in the studied multilayers. Two molecules with different chain lengths were investigated: octadecyl phosphonic and octyl phosphonic acids. Although almost no dependence on the molecule length was observed, the occurrence of premelting is strongly influenced by their lamellar packing configuration. For tilted packings premelting is unfavored while in straight configurations, where alkyl chain interactions are weakened with respect to head-to-head interactions, strong premelting is observed. We find that the onset of premelting occurs at the domain boundaries with straight lamellar configurations and the domain sizes exhibit power law temperature dependences.
Collapse
Affiliation(s)
- M de Pauli
- Departamento de Física, Universidade Federal de Minas Gerais, Avenida Antonio Carlos 6627, Belo Horizonte-MG, CEP: 30123-970, Brazil
| | | | | |
Collapse
|
18
|
Clementi C, Rosi F, Romani A, Vivani R, Brunetti BG, Miliani C. Photoluminescence properties of zinc oxide in paints: a study of the effect of self-absorption and passivation. APPLIED SPECTROSCOPY 2012; 66:1233-1241. [PMID: 23031708 DOI: 10.1366/12-06643] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Zinc oxide has been widely used as a white artist pigment since the end of the eighteenth century. The luminescence properties of this compound have received great interest during the last decades for promising applications in different fields of material science, but their diagnostic implications in the cultural-heritage context have been poorly exploited. This paper is intended to provide a clear picture of the luminescence behavior of zinc white in oil paintings. With this aim, three white pigments and three highly pure (analytical grade) zinc oxides were studied as powder substrates and as painting models by ultraviolet-visible (UV-VIS) fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The quenching of the luminescence intensity of the UV excitonic emission due to self-absorption and multiple scattering phenomena has been investigated, pointing out the possible difficulty of detecting this signal with negative consequences in the diagnostics of works of art. By contrast, the UV emission is notably enhanced by interaction with the binder, whereas the visible emission decreases. This phenomenon is probably due to the formation of covalent bonds between zinc atoms and carboxylates from the lipidic medium that are chemisorbed on zinc oxide surfaces.
Collapse
Affiliation(s)
- Catia Clementi
- Department of Chemistry, University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy
| | | | | | | | | | | |
Collapse
|
19
|
Influence of ZnSt2 on structure of acrylate-based ionomers with different lanthanide (La(III)) ion and acid contents. CHINESE JOURNAL OF POLYMER SCIENCE 2012. [DOI: 10.1007/s10118-012-1125-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
|
20
|
Esterification of Free Fatty Acids Using Layered Carboxylates and Hydroxide Salts as Catalysts. Top Catal 2011. [DOI: 10.1007/s11244-011-9610-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
21
|
Estruga M, Domingo C, Ayllón JA. Solution-processable ZnO nanoparticles obtained by low-temperature solventless synthesis. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm03812a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
22
|
Huang Y, Liao F, Zheng W, Liu X, Wu X, Hong X, Tsang SC. Temperature and solvent-dependent morphological sol gel transformation: an in situ microscopic observation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:3106-3114. [PMID: 20095544 DOI: 10.1021/la904264u] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A thermoreversible self-assemble process from gel (fiber) to sol (vesicle) state in the system alkylamine-ethylene glycol is for the first time monitored by in situ polarized optical microscopy, XRD, (1)H NMR, SEM, SAXRD, FTIR and drop shape analysis. It is found that the solvent molecules are intercalated with alkylamine molecules to form the organogel and vesicle structures. A model based on structural transformation with respect to these alkylamine gelator-solvent assembles is therefore proposed.
Collapse
Affiliation(s)
- Yaqun Huang
- College of Chemistry and Molecular Science, Wuhan University, PR China
| | | | | | | | | | | | | |
Collapse
|
23
|
Cordeiro CS, Arizaga GGC, Ramos LP, Wypych F. A new zinc hydroxide nitrate heterogeneous catalyst for the esterification of free fatty acids and the transesterification of vegetable oils. CATAL COMMUN 2008. [DOI: 10.1016/j.catcom.2008.04.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
24
|
Effect of zinc soaps of rubber seed oil (RSO) and/or epoxidised rubber seed oil (ERSO) on the thermal stability of PVC plastigels. Polym Degrad Stab 2007. [DOI: 10.1016/j.polymdegradstab.2007.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
25
|
Barman S, Vasudevan S. Mixed Saturated−Unsaturated Alkyl-Chain Assemblies: Solid Solutions of Zinc Stearate and Zinc Oleate. J Phys Chem B 2007; 111:5212-7. [PMID: 17441755 DOI: 10.1021/jp068675x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The linear saturated stearic acid and the bent mono-unsaturated oleic acid do not mix and form solid solutions. However, the zinc salts of these acids can. From X-ray diffraction and DSC measurements we show that the layered zinc stearate and zinc oleate salts form a homogeneous solid solution at all composition ratios. The solid solutions exhibit a single melting endotherm, with the melting temperature varying linearly with composition but with the enthalpy change showing a minimum. By monitoring features in the infrared spectra that are characteristic of the global conformation of the hydrocarbon chain, and hence can distinguish between stearate and oleate chains, it is shown that solid solution formation is realized by the introduction of gauche defects in a fraction of the stearate chains that are then no longer linear. This fraction increases with oleate concentration. It has also been possible from the spectroscopic measurements to establish a quantitative relation between molecular conformational order and the thermodynamic enthalpy of melting of the solid solutions.
Collapse
Affiliation(s)
- S Barman
- Solid State and Structural Chemistry Unit, and Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-566012, India
| | | |
Collapse
|