José E. Báez

Universidad de Guanajuato · Department of Chemistry

The ring-opening polymerization (ROP) of l-lactide (l-LA) is the main method for synthesizing poly(l-lactide) (PLLA), in which choosing the catalyst is one of the most important parameters. In this work, we focused on the systematic study of catalysts based on p-block elements from period 5, such as indium(iii), tin(ii), tin(iv) and antimony(iii) a...

Nine different macrodiols derived from α,ω-hydroxy telechelic poly(ε-caprolactone) (HOPCLOH) were prepared by ring-opening polymerization of ε-caprolactone (CL) using three linear aliphatic diols (HO–(CH2)n–OH, where n = 4, 8, and 12) as initiators and catalyzed by ammonium decamolybdate (NH4)8[Mo10O34]. The crystallization temperature (Tc) and cry...

In the quest for sustainable lubrication solutions, the present research explored the potential of five organic compounds as additives in castor oil (CO) to improve its lubricating properties. The compounds tested were curcumin, eugenol, 1,3-Diphenyl-2-propanone, 1,3-Diphenyl-2-propenone, and 1,3-Diphenyl-1,3-propanedione. The main results showed t...

Chemical degradation of PET with natural rubber was carried out. The product obtained was characterized by FTIR, and it was found that the intensity of the vibration signal of the carbonyl group (1719 cm⁻¹) depends on the mass of rubber used in the reaction and not on the PET degradation products, reaching an adequate mass ratio of Rubber/PET = 4....

The objective of this work was to modify banana starch with pineapple leaf fibers (PALF) and its production of biodegradable films. The reaction conditions of the starch modification were a Starch/PALF mass ratio of 50, a time of 1 h and a temperature of 140 °C, to obtain a yield of 41.18 %. Characterization by FTIR and NMR confirmed that the chemi...

Three xanthophylls [(3R,3′R,6′R)-lutein (1), (3R,3′S)-zeaxanthin (2), and (3R,3′S)-astaxanthin (3)] were used for the first time as initiators in the ring-opening polymerization (ROP) of 3-caprolactone (CL) catalyzed by tin(II) 2-ethylhexanoate [Sn(Oct)2] for the synthesis of novel sustainable xanthophyll-containing poly(e- caprolactone)s (xanthoph...

Lubrication is an essential mechanism to make machines and engines more efficient by lowering friction and wear. Despite this, to mitigate environmental damage, lubricants must come from renewable sources and be biodegradables. Therefore, this study analyzed the use of Curcumin as a natural additive in two green oils to improve their tribological a...

Resumen Los lubricantes se han venido empleando desde las primeras máquinas y mecanismos. Hoy en día se fabrica una gran variedad de lubricantes de distinta naturaleza y para diversas aplicaciones. Erradamente, desde un primer punto de vista, podemos atribuir el desempeño de un lubricante exclusivamente a las propiedades físicas del mismo, es decir...

Synthesis of the starch/silicone oil composite carried out and its structural characterization by FTIR, Raman and 29Si NMR allowed to identify functional groups of the composite. The synthesis conditions were a starch/silicone oil mass ratio of 2.0 and a temperature of 150 oC to obtain a yield of 84.63 %. SEM analysis showed that the starch granule...

The banana starch reaction with polyethylene using ethylene carbonate was carried out by varying the starch/ethylene carbonate mass ratio (50–1000%). The starch-g-PE mass yield reached 89% mass conversion and a grafting yield of 0.52 when a starch/EC = 0.5 ratio was used, while the mass yield decreased until reaching a value of 26% when the starch/...

Chemical modification of banana starch (Musa paradisiaca L.) with the degradation products of virgin and bottle waste of polyethylene terephthalate was carried out in situ. The modified starch was characterized by FTIR and NMR, which allowed proposing three chemical structures. SEM micrographs showed that the morphology of the modified starch granu...

The present study focuses on an introductory analysis of the use of three xanthophylls as additives for green lubricant applications. For this purpose, the additives were characterized by FTIR and 1H-NMR techniques, and the bio-lubricants were described by their physical properties. The effect of the natural compounds on the friction and wear prope...

There is still an incomplete defined number of the members of the genus Crataegus (hawthorn) (Rosaceae). Phipps and co-workers estimated between 150 and 200, Tassel and collaborators, 300, while others provide different numbers of species. Most of these plants are employed worldwide in traditional, and now as adjuvants in modern medicines, for the...

Terpenes with olefin methyl branches and bifunctional hydroxyl groups were used as initiators in the ring-opening polymerization of ε-caprolactone (CL) catalyzed by ammonium decamolybdate (NH4)6[Mo7O24], resulting in α-hydroxyl-ω-olefin poly(ε-caprolactone) (PCL) (Co–PCL–OH). The degree of polymerization was kept low (5 and 10) in all the species t...

Three neutral hexacoordinate silicon(IV) complexes with SiN6 skeleton were obtained via one-pot synthesis by using tetra(thiocyanato-N)silane, Si(NCS)4 with an equimolar amount of 2,2′-bipyridyl (bipy), 4,4′-dimethyl-2,2′-dipyridyl (dmp) and 1,10-phenanthroline (phen) respectively. The complexes obtained; (bipy)Si(NCS)4 (1), (dmp)Si(NCS)4 (2), and...

Synthesis of the starch/silicone composite carried out and its structural characterization by FTIR, Raman and ²⁹ Si NMR allowed to identify functional groups of the composite. The synthesis conditions were a starch/silicone mass ratio of 2.0 and a temperature of 150 o C to obtain a yield of 84.63 %. SEM analysis showed that the starch granules were...

Resumen: Cuatro muestras de ámbar con diferentes colores de Simojovel en el estado de Chiapas México, fueron analizadas para conocer sus diferencias y similitudes en términos de su naturaleza química. En este trabajo se caracterizaron los ámbares por espectroscopía de infrarrojo. Los espectros de infrarrojo mostraron bandas de diferentes grupos fun...

The PA6G blue is a polymeric material for great versatility of engineering applications that required good mechanical and tribological properties such as gears. The focus of this study was to investigate the mechanical properties as well as the friction and wear resistance of a commercial PA6G blue under biodegradable external lubrication, to evalu...

Banana starch was modified with B bis(2-hydroxyethyl) terephthalate and its instrumental characterization allowed to propose a chemical structure. In the carbon 6 (C6) of the starch the modification reaction was carried out. The morphology of starch changes due to its chemical modification. The modified starch showed a lower crystallinity and therm...

The ring-opening polymerization (ROP) of L-lactide (L-LA) was induced by the catalytic action of bismuth subsalicylate (BiSS) using linear aliphatic diols [HO(CH2)nOH, where n = 2, 3, 4, 5, 6, and 8] as initiators and chain transfer agents. The theoretical and experimental degree of polymerization (DP) in all samples of α,ω-hydroxy telechelic poly(...

The Cover Picture shows Straightforward Synthesis of Neutral Hexacoordinate Sn(IV) with 4,4'‐Dimethyl‐2,2'‐dipyridyl (DMB) and SnX4, X = Cl, Br, and I, Crystal Structure, Pre‐catalyst for ROP of ɛ‐Caprolactone and DFT Structural and ¹¹⁹Sn NMR Studies of the Hypothetical (DMB)SnX4, X = F, and At. More details can be found in the Article by Fátima Gó...

Linear aliphatic oligoesters derived from δ-valerolactone (VL) and ε-caprolactone (CL) were synthesised by ring-opening polymerisation (ROP) using 1-docosanol (C22H45OH, C22OH) and aluminum isopropoxide [Al(OⁱPr)3] as initiator and catalyst, respectively. Monodisperse species such as monomers, dimers, trimers, and tetramers with terminal groups α-h...

A series of three neutral, hexacoordinate tin(IV) complexes were synthesized by the reaction of 4,4´‐dimethyl‐2,2’‐bipyridine (DMB) with SnX 4 , X = Cl, Br, and I, as starting materials. The complexes (DMB)SnX 4 were characterized in solution by 1 H, 13 C, and 119 Sn NMR spectroscopy, and in the solid‐state by 119 Sn MAS NMR. In addition, single‐cr...

The objective of this paper was to perform a copolymerization between polyethylene and starch in order to obtain new environmentally friendly materials. The copolymer obtained was characterized thermally, morphologically and structurally, including its pasting profile. The starch-g-PE copolymer showed lower thermal stability compared to the control...

El ámbar es un material antiguo que ha sido utilizado en joyería desde civilizaciones antiguas. Además, el ámbar ha demostrado ser un medio de preservación de especies extintas que vivieron hace millones de años como insectos, arácnidos y reptiles. El ámbar es una resina fosilizada que está formada de una mezcla compleja de compuestos orgánicos lla...

En el año 2019 se cumplen los 150 años del descubrimiento de la tabla periódica por parte del químco ruso Dimitri I. Mendeléiev, en este ensayo se ilustra de manera amena y en un lenguaje accesible la importancia de la aportación científica de la tabla periódica en un contexto histórico y práctico.

En este trabajo se relata la historia del redescubrimiento del vanadio en Suecia por Nils Sefström y como éste fue reconocido ser el mismo elemento (eritronio), que había descubierto Andrés Manuel del Río en México, por Friedrich Wöhler en Alemania. La controversia suscitada por conservar el nombre del vanadio, hecha por J. J. Berzelius, y otorgarl...

A series of twenty segmented poly(ester-urethane)s (PEUs) were synthesized, by the reaction of four different macrodiols derived from ε-caprolactone (CL) and 1,8-octanediol (Oct), 1,6−hexamethylene diisocyanate (HDI), and three different carotenoids, (3R,3´R,6´R)−lutein (1) obtained from a renewable source such as marigold (Tagetes erecta L.), (3R,...

Although much has been learned and investigated about environmentally friendly lubricants in recent years, several issues remain critical to their use in specific applications. A key point that could be limiting their utilization is that the effect of green lubricants on the tribological and mechanical properties of the elements has not been thorou...

Since ancient times, lubricants have been used to reduce friction and wear problems of mechanical systems. However, nowadays, there is a constant effort to improve their performance through additives so that they can accomplish properly in this modern world. In that sense, in this study, it was proposed the use of Poly(ε-Caprolactone) (PCL) as a bi...

Poly(caprolactone) (PCL) was synthesized from the polymerization of ε-caprolactone (CL) with degraded poly(ethylene terephthalate) (PET) for its functionalization using heptamolybdate of ammonium and tin(II) 2-ethylhexanoate, as catalyst and initiator, respectively. Polymerization of CL with bis(2-hydroxyethyl) terephthalate (BHET) was carried out...

En 1801, el químico minerólogo español Andrés Manuel del Río Fernández descubrió un nuevo elemento en una 'mena de plomo pardo' (vanadinita Pb5(VO4)3Cl), un mineral de la mina del Cardonal en el distrito de Zimapán, Hidalgo, México. Sin embargo, los análisis erróneos de Collet-Descotils retrasaron el anuncio de la existencia del elemento 23. En 182...

Carotenoids are natural compounds that have important roles in promoting and maintaining human health. Synthetic astaxanthin is a highly requested product by the aquaculture industry, but natural astaxanthin is not. Various strategies have been developed to synthesize this carotenoid. Nonetheless, these approaches have not only provided limited glo...

α,ω-Hydroxy telechelic poly(ε-caprolactone) (HOPCLOH) was synthesized by ring-opening polymerization (ROP) of ε-caprolactone (ε-CL).The ROP was catalyzed by ammonium decamolybdate in the presence of ether diols [HO-(CH2-CH2-O)m-H] (where m = 2, 3, 4, 5, 6, and 8) as initiators. The homopolymer HOPCLOH was obtained with the ether group (EG) [HO-PCL-...

Ether group (E) diols [HO(CH2CH2O)xH, x = 2, 3, 4, 5, 6, and 8] and polyethylene glycol (PEG) [HO(CH2CH2O)xOH] were used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) catalyzed by ammonium decamolybdate to synthesize the poly(ε-caprolactone) (PCL) macrodiols such as HOPCL–E–PCLOH and HOPCL–PEG–PCLOH, respectively. Th...

Lubricants have much importance in several industries, principally serving to reduce friction and wear in mechanical elements. In this study, the influence of Castor oil as bio-lubricant on the friction and wear performance of AISI 4140 steel was investigated. For that purpose, pin-on-disk friction tests were conducted according to ASTM G-99, by us...

α,ω-Hydroxy telechelic poly(L-lactides) (HOPLLAOH) were synthesized by ring-opening polymerization of the L-lactide (L-LA) catalyzed by tin octoate [Sn(Oct)2] in the presence of two different types of initiators such as alkyl diols [HO−(CH2−CH2)m−OH] and ether diols [HO−(CH2−CH2−O)m−H] (where m = 2, 3, 4, 5, 6, and 8), and eventually, two different...

Diblock copolymers of poly(methylene-b-ε-caprolactone) (PM-b-PCL) were synthesized in two steps: a) polyhomologation, to obtain following oxidative cleavage of the carbon-boron, (PM, block1), an α-hydroxyl-ω-methyl polymethylene (PMOH, CH3−[CH2]m−OH). Following transfer reaction to the ring-opening polymerization catalyst and b) ring-opening polyme...

Starch-g-PCL films were prepared using the casting method and were characterized by different instrumental techniques and physicochemical properties. Nuclear magnetic resonance and Fourier transform infrared spectroscopy led to the proposal of a chemical structure for the films. The Scanning electron micrographs (SEM) of the films showed the format...

α,ω-Hydroxy telechelic poly(ε-caprolactone)s (HOPCLOHs) were prepared by ring-opening polymerization (ROP) of the ε-caprolactone (CL) catalyst by ammonium decamolybdate (NH4)8[Mo10O34] in the presence of different aliphatic diols [HO-(CH2)m-OH, where m = 2,4,6,7,8,10,12,14,16] as initiators to obtain a family of HOPCLOH [HO-PCL-O-(CH2)m-O-PCL-OH, m...

Bioresorbable linear poly(ether-ester-urethane)s with different hydrophilic characteristics were synthesized from triblock copolymers of poly(ε-caprolactone)-poly(ethylene oxide)-poly(ε-caprolactone) (PCL-PEO) as macrodiols, and L-lysine diisocyanate (LDI) or hexamethylenediisocyanate (HDI) were used as the required diisocyanates. Macrodiols were o...

Polyethylene oxide (PEO)-based polymers containing long PEO chains are one of the best materials for postcombustion processes, attending to their separation properties. Optimal conditions for the application of the membrane separation module are immediately after elimination of water vapor, NO x , SO2, and dust particles, where the temperature of t...

The chemical modification of physiologically immature banana (Musa paradisiaca L.) was performed via the in situ polymerization of ϵ-caprolactone (CL) utilizing ammonium decamolybdate as a catalyst to obtain a starch-g-PCL copolymer in one step. The copolymerization conditions were studied by varying the CL/catalyst mass ratio, the reaction tempera...

A series of α, ω-hydroxy telechelic poly(L-lactide)s (HOPLLAOHs) were synthesized by ring-opening polymerization (ROP) of L-lactide (L-LA) using tin octoate [Sn(Oct)2] as catalyst and a family of linear alkyl diols as initiators (HO-(CH2)m-OH), where m = 2,4,6,8,10 and 12). A systematic analysis of these HOPLLAOHs species in terms of their thermal...

The synthesis of the graft copolymer starch-g-PCL was carried out in a single phase, using molybdenum oxide as a catalyst, at a temperature of 150°C over a period of 24h. Infrared spectroscopy and nuclear magnetic resonance analyses indicated that the graft copolymer was successfully synthesized, obtaining an 84% conversion yield. The introduction...

This work is an introduction to the polymer chemistry, with a focus toward polymer synthesis with degradable properties as poly(e-caprolactone) (PCL). PCL is a polyester with five methylenes and one ester group [----O----(CH2)5----CO----]n as repeating unit in the polymer. Ring-opening polymerization (ROP) of e-caprolactone (CL) is the most conveni...

Tres diferentes tipos de reacciones utilizando grupos terminales en polímeros fueron analizados para la síntesis de copolímeros dibloque, tales como: a) los grupos azida (RN3) y el alquino (RCCH) para obtener una cicloadición 1,3-dipolar (química clic); b) los polímeros α,ω−hidoxi-telequélicos (HOROH) y los diisocianatos (OCNRNCO) para sintetizar p...

Following its resolution by diastereomeric complexation, 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane (TTSBI) was used to synthesize a chiral ladder polymer, (+)-PIM-CN. (+)-PIM-COOH was also synthesized by the acid hydrolysis of (+)-PIM-CN. Following characterization, both (+)-PIM-CN and (+)-PIM-COOH were solvent cast directly...

Following its resolution by diastereomeric complexation, 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane (TTSBI) was used to synthesize a chiral ladder polymer, (+)-PIM-CN. (+)-PIM-COOH was also synthesized by the acid hydrolysis of (+)-PIM-CN. Following characterization, both (+)-PIM-CN and (+)-PIM-COOH were solvent cast directly...

The biodegradable aliphatic oligoesters polyglycolide (PGA), poly(L-lactide) (PLLA), and poly(-caprolactone) (PCL) with similar number-average molecular weight M n values but different linear alkyl end groups [CH3−[CH2−CH2]m−CH2−] were compared in terms of their physical properties, parameters such as melting temperature (T m), crystallinity (x i),...

Twenty seven poly(ester−urethane−amide)s (PEUAs) were synthesized from the reaction of α,ω-telechelic poly(ε-caprolactone) diols, 1,6-hexamethylene diisocyanate, and three different diamide−diol chain extenders derived from ε-caprolactone and three aliphatic diamines with increasing length (n = 2, 4, and 6). The hard segment (HS) was designed to be...

Four different miktoarm star copolymers poly(ethylene glycol-(e-caprolactone)2) diol [PEG-PCL2] were obtained using a-diol-x-methoxy poly(ethylene glycol) [MPEG-(OH)2] as macroinitiator/chain transfer agent in the ring opening polymerization (ROP) of e-caprolactone (CL) catalyzed by tin(II) 2-ethylhexanoate [Sn(Oct)2]. PEG-PCL2 and 1,6-hexamethylen...

Poly(L-lactide) (PLLA) oligo-esters with α-hydroxyl-ω-alkyl (alkyl = −CH2−[CH2−CH2]m−CH3, where m=1, 2, 4, 5, 6, 7, 8, 9, and 10) end groups were synthesized by ring-opening polymerization of L-lactide (L-LA) catalyzed by tin(II) 2-ethylhexanoate Sn(Oct)2 in the presence of aliphatic alcohols as initiators (HO−CH2−[CH2−CH2]m−CH3, where m=1, 2, 4, 5...

Trifluoroacetic anhydride (TFAA) and asymmetric telechelic α-hydroxyl-ω-(carboxyl acid) poly(ϵ-caprolactone) (HA-PCL) were used to obtain in situ α-trifluoroacetate-ω-trifluoroacetanhydride poly(ϵ-caprolactone) (TF-PCL). After reaction, the polymer was characterized by 1H and 13C NMR, MALDI-TOF, FT-IR, DSC, and TGA. Under the influence of TF-PCL an...

Poly(ϵ-caprolactone) (PCL) oligomers with α-hydroxyl-ω-alkyl end groups (alkyl =–CH2–[CH2–CH2]m–CH3, where m = 1, 2, 4, 5, 6, 7, 8, 9, and 10) were synthesized by ring-opening polymerization (ROP) of ϵ-caprolactone (CL) catalyzed by ammonium decamolybdate (NH4)8[Mo10O34] and using aliphatic primary alcohols as initiators (HO–CH2–[CH2–CH2]m–CH3, whe...

Poly(glycolide) (PGA) oligomers were obtained by ring-opening polymerization (ROP) of glycolide (GA) catalyzed by ammonium decamolybdate (NH4)8[Mo10O34] and using aliphatic primary alcohols as initiators/chain transfer agents (HO‒CH2‒[CH2‒CH2]m‒CH3, where m = 1, 2, 4, 5, 6, 7, 8, 9, and 10). High yield (85–95%) and short reaction time (15 min) were...

An aliphatic polyester with degradable characteristics as poly(D,L-lactide) (PDLLA) was synthesized by ring-opening polymerization (ROP) of the D,L-lactide using tin (II) 2-ethylhexanoate as initiator and primary alcohols as coinitiators. PDLLA was characterized by proton nuclear magnetic resonance (¹H NMR). The concepts and synthesis that are show...

Poly(ethylene-b-ε-caprolactone) (PE-b-PCL) diblock copolymers were synthesized by ring-opening polymerization (ROP) of ε-caprolactone (CL) with α-hydroxyl-ω-methyl polyethylene (PE-OH) as a macroinitiator and ammonium decamolybdate (NH4)8[Mo10O34] as a catalyst. Polymerization was conducted in bulk (130–150°C) with high yield (87–97%). Block copoly...

Este trabajo relaciona la cotidianidad de los colores de flores, vegetales y pescados como el salmón, con la química que existe detrás de los pigmentos que les dan esa tonalidad, señalando la naturaleza no solo visual, sino además como participan los compuestos químicos responsables de dichos pigmentos en el mejoramiento de la salud humana. I. Gene...

A new convenient route for the synthesis of poly(ɛ-caprolactone) (PCL) with α,ω-telechelic diols' end-groups is presented. Synthesis of α,ω-telechelic PCL diols (HOPCLOH) was achieved by ring-opening polymerization (ROP) of ɛ-caprolactone (CL) catalyzed with ammonium decamolybdate (NH4)8[Mo10O34] and using diethylene glycol (DEG) as initiator. Obta...

ε-Caprolactone and δ-valerolactone were polymerized in bulk at 150°C using the ruthenium(II) complex RuCl2(PPh3)3 as initiator in the presence of 1,3-propanediol (PD) with a series of alcohols as coinitiators. Polymerization of lactones proceeds via ruthenium(II) alkoxide active centers. 1H-NMR analysis revealed that the ruthenium complex reacted w...

Eight different molybdenum compounds were tested in the catalysts of ring-opening polymerization (ROP) of ε-caprolactone (CL). All homopolymerizations were conducted in bulk at 150 °C using a CL/molybdenum compound molar ratio of 200. Ammonium decamolybdate (NH4)8[Mo10O34] comes to be the best catalyst for ROP, based on its selectivity, short react...

Asymmetric telechelic α-hydroxyl-ω-(carboxylic acid) poly(ε-caprolactone) (HA-PCL) and α-hydroxyl-ω-(carboxylic acid) poly(δ-valerolactone) (HA-PVL) were synthesized by ring-opening polymerization of ε-caprolactone (CL) and δ-valerolactone (VL), respectively. HA-PCL oligomers were obtained at 150 °C in 2 h using ammonium decamolybdate (NH4)8[Mo10O3...

An efficient process for the ring-opening polymerization (ROP) of lactones by ammonium decamolybdate (NH4)8[Mo10O34] (obtained in situ from thermal decomposition of ammonium heptamolybdate (Hep) (NH4)6[Mo7O24]), is reported for the first time. Polymerization of the ε-caprolactone (CL) and δ-valerolactone (VL) proceeds with quantitative conversions,...