Browsing by Author "Ortiz, Pablo A."

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    A new porous organic polymer containing Troger's base units: Evaluation of the catalytic activity in Knoevenagel condensation reaction
    (2021) Rodriguez-Gonzalez, Fidel E.; Niebla, Vladimir; Velazquez-Tundidor, M. V.; Tagle, Luis H.; Martin-Trasanco, Rudy; Coll, Deysma; Ortiz, Pablo A.; Escalona, Nestor; Perez, Edwin; Jessop, Ignacio A.; Terraza, Claudio A.; Tundidor-Camba, Alain
    The classic Tro center dot ger's base polymerization of a diamine and dimethoxymethane with trifluoroacetic acid as catalyst generated a Tro center dot ger's base-type polymer (TBP), which exhibited the absolute insolubility in a variety of organic solvents because of its highly aggregated model. A new porous organic polymer was obtained by a simple Tro center dot ger's base polymerization reaction between a diamine and formaldehyde in the form of acetal in the presence of trifluoroacetic acid as catalyst. Tro center dot ger's base-type polymer (TBP) resulted insoluble in a wide range of organic solvents due to its rigid and aromatic structure. TBP was characterized spectroscopically (FT-IR), thermally and morphologically. As result, a thermostable and amorphous polymer bearing pores ranging between 50 and 300 nm and macro-voids of up to 12 mu m was obtained. Due to the insolubility of the TBP, it was tested as a metal-free heterogeneous catalyst in the Knoevenagel condensation reaction, showing a high efficiency. For this, the optimal catalyst load, reaction time and reuse of the catalyst were studied using benzaldehyde and malononitrile as substrates. Furthermore, aldehydes with variable chain sizes and ethyl cyanoacetate replacing malononitrile were tested as substrate with a high percent of conversion (97-99%).
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    Biodegradable gelatin-based films with nisin and EDTA that inhibit Escherichia coli
    (2022) Abarca, Romina L.; Medina, Javiera; Alvarado, Nancy; Ortiz, Pablo A.; Carrillo Lopez, Bernardo
    In this study, we developed gelatin-based films for active packaging with the ability to inhibit E. coli. We created these novel biodegradable gelatin-based films with a nisin-EDTA mix. FT-IR, TGA, and SEM analysis showed that nisin interacted with the gelatin by modifying its thermal stability and morphology. The use of nisin (2,500 IU/mL) with concentrations of Na-EDTA (1.052 M stock solution) distributed in the polymer matrix generated a significant decrease in the growth of E. coli when compared to the control. In freshly made films (t(0)), the growth of E. coli ATCC 25922 was reduced by approximately 3 logarithmic cycles. Two weeks after the films were made, a reduction in antimicrobial activity was observed in approximately 1, 1 and 3 logarithmic cycles of the films with 5%, 10% and 20% of the compound (nisin/Na-EDTA) distributed in the polymer matrix, respectively. This evidences an antimicrobial effect over time. Also, biodegradation tests showed that the films were completely degraded after 10 days. With all these results, an active and biodegradable packaging was successfully obtained to be potentially applied in perishable foods. These biodegradable, gelatin-based films are a versatile active packaging option. Further research on the barrier properties of these films is needed.
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    Development of Novel Phase-Change Materials Derived from Methoxy Polyethylene Glycol and Aromatic Acyl Chlorides
    (2023) Angel-Lopez, Alejandro; Norambuena, Angel; Arriaza-Echanes, C.; Terraza, Claudio A.; Tundidor-Camba, Alain; Coll, Deysma; Ortiz, Pablo A.
    In this research, novel, organic, solid-liquid phase-change materials (PCMs) derived from methoxy polyethylene glycol (MPEG) and aromatic acyl chlorides (ACs) were prepared through a condensation reaction. The MPEGs were used as phase-change functional chains with different molecular weights (350, 550, 750, 2000, and 5000 g/mol). The aromatic ACs, terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC), were employed as bulky linker cores. Solubility tests demonstrated that this family of PCMs is soluble in protic polar solvents such as H2O and MeOH, and insoluble in nonpolar solvents such as n-hexane. Fourier-ransform infrared spectroscopy (FT-IR UATR) and nuclear magnetic resonance (H-1, C-13, DEPT 135 & DEG;, COSY, HMQC, and HMBC NMR) were used to confirm the bonding of MPEG chains to ACs. The crystalline morphology of the synthesized materials was examined using polarized optical microscopy (POM), revealing the formation of spherulites with Maltese-cross-extinction patterns. Furthermore, it was confirmed that PCMs with higher molecular weights were crystalline at room temperature and exhibited an increased average spherulite size compared to their precursors. Thermal stability tests conducted through thermogravimetric analysis (TGA) indicated decomposition temperatures close to 400 & DEG;C for all PCMs. The phase-change properties were characterized by differential scanning calorimetry (DSC), revealing that the novel PCMs melted and crystallized between -23.7 and 60.2 & DEG;C and -39.9 and 45.9 & DEG;C, respectively. Moreover, the heat absorbed and released by the PCMs ranged from 57.9 to 198.8 J/g and 48.6 to 195.6 J/g, respectively. Additionally, the PCMs exhibited thermal stability after undergoing thermal cycles of melting-crystallization, indicating that energy absorption and release occurred at nearly constant temperatures. This study presents a new family of high-performance organic PCMs and demonstrates that the orientation of substituent groups in the phenylene ring influences supercooling, transition temperatures, and thermal energy storage capacity depending on the MPEG molecular weight.
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    Ionenes as Potential Phase Change Materials with Self-Healing Behavior
    (2023) Arriaza-Echanes, Carolina; Velazquez-Tundidor, Maria V.; Angel-Lopez, Alejandro; Norambuena, Angel; Palay, Francisco E.; Terraza, Claudio A.; Tundidor-Camba, Alain; Ortiz, Pablo A.; Coll, Deysma
    Ionenes are poly(ionic liquids) (PILs) comprising a polymer backbone with ionic groups along the structure. Ionenes as solid-solid phase change materials are a recent research field, and some studies have demonstrated their potential in thermal dissipation into electronic devices. Eight ionenes obtained through Menshutkin reactions were synthesized and characterized. The analysis of the thermal tests allowed understanding of how the thermal properties of the polymers depend on the aliphatic nature of the dihalogenated monomer and the carbon chain length. The TGA studies concluded that the ionenes were thermally stable with T10% above 420 degrees C. The DSC tests showed that the prepared ionenes presented solid-solid transitions, and no melting temperature was appreciated, which rules out the possibility of solid-liquid transitions. All ionenes were soluble in common polar aprotic solvents. The hydrophilicity of the synthesized ionenes was studied by the contact angle method, and their total surface energy was calculated. Self-healing behavior was preliminarily explored using a selected sample. Our studies show that the prepared ionenes exhibit properties that make them potential candidates for applications as solid-solid phase change materials.
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    New polyimides containing methyl benzamidobenzoate or dimethyl benzamidoisophthalate as bulky pendant groups. Effects on solubility, thermal and gas transport properties
    (2022) Terraza, Claudio A.; Cruz, Yennier; Rodriguez, Ary; Victoria Velazquez-Tundidor, Maria; Hauyon, Rene A.; Rodriguez-Gonzalez, Fidel E.; Niebla, Vladimir; Aguilar-Vega, Manuel; Sulub-Sulub, Rita; Coll, Deysma; Ortiz, Pablo A.; Perez, Yasmin P.; Comesana-Gandara, Bibiana; Tundidor-Camba, Alain
    This work reports the synthesis of six new polyimides obtained by the reaction of two novel diamine monomers: methyl 4-(3,5-diaminobenzamido)benzoate and dimethyl 5-(3,5-diaminobenzamido)isophthalate, bearing one or two methyl ester groups in their phenyl rings, respectively, with three known dianhydrides, 4,4 '-(hexafluoroisopropylidene) diphatalic anhydride (6FDA), 4,4 '-(dimethylsilanediyl) dipthalic anhydride (SiDA) and 4,4 '-oxydiphthalic anhydride (ODPA). The polyimides were synthesized using the "two-step" method, which first involves forming a poly(amic acid) precursor that is subsequently cyclodehydrated to form the imide linkage. The yields were higher than 95% in all cases, and the structural characterization was performed by spectroscopic techniques like FT-IR, H-1, C-13, and Si-29 NMR. In addition, the effect on the solubility in common organic solvents and thermal and gas transport properties of these polyimides were studied as a function of the nature of the respective side group and the dianhydride used.
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    Novel Polyelectrolytes Obtained by Direct Alkylation and Ion Replacement of a New Aromatic Polyamide Copolymer Bearing Pyridinyl Pendant Groups
    (2021) Bonardd, Sebastian; Angel, Alejandro; Norambuena, Angel; Coll, Deysma; Tundidor-Camba, Alain; Ortiz, Pablo A.
    The following work shows, for the first time, the synthesis and characterization of a new family of polyelectrolytes, along with their preliminary assessments in terms of desalin water treatment. These materials fall into the category of aromatic co-polyamides, which are obtained by the direct condensation of monomers 4,4 '-oxydianiline (ODA), isophthaloyl chloride, and 3,5-diamino-N-(pyridin-4-ylmethyl)benzamide (PyMDA). Thereby, the charged nature exhibited by these materials was achieved through the quaternization of PyMDA moieties using linear iodoalkanes of different lengths (CnI with n = 1, 2, 4, and 6). After completing the quaternization process, polyelectrolytes were subjected to a one-step anion substitution process, where iodide counterions were replaced by bis(trifluoromethane)sulfonamide entities. For all the obtained materials, solubility tests were carried out, showing that those alkylated with methyl and ethyl chains exhibit high solubility in rutinary aprotic polar solvents, while those containing n-butyl and n-hexyl units resulted in the formation of insoluble gels. Due to the above, the latest were discarded from this study early on. The structural characterization of the initial neutral co-polyamide was carried out by means of infrared spectroscopy (FT-IR), nuclear magnetic resonance (H-1, C-13-NMR), and size-exclusion chromatography (SEC), while the structure of methylated and ethylated polyelectrolytes was successfully confirmed through FT-IR, H-1, C-13, and F-19-NMR. Additionally, the thermal behavior of these materials was analyzed in terms of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), showing thermal degradation temperatures above 300 degrees C and glass transition temperatures (Tg) above 200 degrees C, resulting in polymers with outstanding thermal properties for water treatment applications. On the other hand, through the solvent-casting method, both neutral and charged polymers were found to be easily prepared into films, exhibiting a remarkably flexibility. The mechanical properties of the films were analyzed using the traction test, from which tensile strength values ranging between 83.5 and 87.9 Mpa, along with Young's modulus values between 2.4 and 2.5 Gpa were obtained. Moreover, through contact angle measurements and absorption analysis by immersion, polyelectrolytes showed important changes in terms of affinity against polar and polar substances (water, n-heptane, and benzene), exhibiting a higher rejection regarding the neutral polymer. Finally, as a preliminary test against the seepage of saline waters, thin polymer films (from 11.4 to 17.1 mu m) were deposited on top of commercial filter discs and tested as filters of saline solutions ([NaCl] = 1000 and 2000 ppm). These tests revealed a decrease of the salt concentration in the obtained filtrates, with retention values ranging between 6.2 and 20.3%, depending on the concentration of the former solution and the polymer used.
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    Poly(ether-imide-amide)s obtained from bis[4-(4-aminophenoxy)phenyl] diphenylsilane and dicarboxylic acids derivatives of bis(3,4-dicarboxyphenyl)dimethylsilane anhydride combined with L-aminoacids
    (2016) Terraza Inostroza, Claudio; Tagle Domínguez, Luis Hernán; Muñoz, Daniela; Tundidor Camba, Alain; Ortiz, Pablo A.; Coll Herrera, Deysma; González Enríquez, Carmen; Jessop Rivera, Ignacio; Terraza Inostroza, Claudio; Tagle Domínguez, Luis Hernán; Muñoz, Daniela; Tundidor Camba, Alain; Ortiz, Pablo A.; Coll Herrera, Deysma; González Enríquez, Carmen; Jessop Rivera, Ignacio
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    Synthesis of dimethyl- and diphenylsilane-based oligo(azine)s: Thermal, optical, electronic, and morphological properties
    (2022) Sobarzo, Patricio A.; Jessop, Ignacio A.; Perez, Yasmin; Hauyon, Rene A.; Velazquez-Tundidor, Maria V.; Medina, Jean; Gonzalez, Alexis; Garcia, Luis E.; Gonzalez-Henriquez, Carmen M.; Coll, Deysma; Ortiz, Pablo A.; Tundidor-Camba, Alain; Terraza, Claudio A.
    Four new oligo(azine)s were synthesized from dimethyldiphenylsilane and tetraphenylsilane core-based dialdehydes and hydrazine by high-temperature polycondesation and proposed as materials for optoelectronic applications. The oligo(azine)s were characterized by EA, FT-IR, and NMR. Although most of samples were poorly soluble, TPS-containing PAZ-4 was soluble in aprotic polar solvents. According to SEC and FT-IR studies, the samples were oligomers with up to five repeating units long. TGA showed highly stable samples with TDT10% over 420 degrees C except for PAZ-1 that contains a DMS core along with phenyl units, and thus, the lowest carbon content in the series. From DSC analysis, the substitution of phenyl groups in PAZ-1/3 by biphenyl moieties in PAZ-2/4 allowed to obtain oligo(azine)s with lower T-g values. PAZ-4 showed a UV-A absorption with optical band-gap values of 2.91 and 2.65 eV from UV-vis (solution) and DRS (films), respectively. PL analysis showed a violet emission. PAZ-4 showed resistivity of 29.24 omega cm, similar to wide-band gap materials. Their contact angle measurements showed a critical surface tension of 42.29 dynes/cm, revealing its hydrophobicity. AFM analysis indicated that the PAZ-4 films had homogeneous surfaces. Young's modulus close to 4.46 GPa was established by microindentation for the PAZ-4 thin-films.
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    SYNTHESIS, CHARACTERIZATION AND FILM PREPARATION OF NEW CO-POLYIMIDE BASED ON NEW 3,5-DIAMINO-N-(PYRIDIN-4-YLMETHYL)BENZAMIDE, ODA AND 6FDA
    (2018) Tundidor-Camba, Alain; Saldias, Cesar; Tagle, Luis H.; Terraza, Claudio A.; Coll, Deysma; Perez, German; Aguilar-Vega, Manuel; Abarca, Romina L.; Ortiz, Pablo A.
    This work describes mainly the synthesis and characterization of new co-polyimides obtained from the polycondensation of the dianhydride 4,4'-(hexafluoroisopropylidene)diphtlialic anhydride (6FDA), 4,4'-oxydianiline (ODA) and the new diamine 3,5-diamino-N-(pyridin-4-ylmethyl)benzamide (PyDA). It describes as the different compositions of ODA and PyDA present in the polymers. produce variation on thermal and mechanical properties, which are important characteristics for the development of future nanocomposites derived from these polymers. Both PyDA monomer and polymers were characterized using FT-IR and NMR (H-1, C-13, F-19, dept 135 degrees, COSY, HMBC, HMQC) spectroscopy. The inherent viscosity of polymers is between 0.3 to 1.49 dL/g, they are soluble in aprotic polar solvents, such as: DMSO, DMF and DMA. In addition, all co-polymers showed thermal decomposition temperature and glass transition temperatures above 483 degrees C and 289 degrees C, respectively. Mechanical tests under tension of co-polymer films showed Young's modulus between 2.1-3.9 GPa and tensile strength between 35.5 and 120.0 MPa. On the other hand, an increase in crystallinity and hydrophilicity is observed when increasing the amount of pyridinyl groups.
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    Tri-functional oligomeric polyesters prepared from new dicarboxylic acids containing several amino acids residues by Higashi methodology: synthesis, characterization, and study of solubility and thermal behavior
    (2021) Tundidor-Camba, Alain; Tagle, Luis H.; Terraza, Claudio A.; Rivera, Jorge; Coll, Deysma; Ortiz, Pablo A.
    The synthesis of polyfunctional aliphatic oligomeric polyesters (poly(ether-imido-esters;PEIEs) containing several amino acid residues is described, and their thermal properties and solubility behavior were studied. The new symmetrical monomeric dicarboxylic acids were synthesized using 4-nitrophthalonitrile as starting material, which reacted with bisphenol-A or bis(4-hydroxyphenyl)diphenylmethane. Then, the tetranitrile derivatives were hydrolyzed to the tetracarboxylic acids and dehydrated to the respective dianhydrides. Finally, these compounds reacted with the amino acids glycine orL-alanine to obtain the aliphatic dicarboxylic acid monomers.PEIEs were obtained by Higashi methodology from these monomers and bisphenol-A, characterized by elemental analysis, NMR and IR, and the results were in agreement with the structures. The materials were soluble at 25 degrees C in several aprotic polar organic solvents and some in CHCl(3)and THF. In agreement with the viscosity and SEC results,PEIEswere oligomers with degree of polymerization of four and six, and Mw and Mn between 7370-9790 g/mol and 3680-4850 g/mol, respectively. The samples showed lowT(g)values (124-160 degrees C), associated with important structural flexibility promotes by dicarboxylic acid monomers. Despite this, this parameter depended of the aminoacidic residue nature in the sense that when the volume of it increased, theT(g)also increased due to a decrease in the free rotation that negatively affects the segmental movements of the chains. This effect was also observed when the side groups of the diphenol moiety of the dicarboxylic acid monomers increase from methyl to phenyl. The recorded TDT(10%)values from the TGA analysis (334-457 degrees C) do not allow to consider these samples as thermoset materials. In this sense, it was possible to observe an average increase of 8-13 degrees C and 23-28 degrees C when the lateral group volume of the amino acid residues and of the diphenol moiety are increased, respectively.