Synthesis of a Curing Agent Derived from Limonene and the Study of Its Performance to Polymerize a Biobased Epoxy Resin Using the Epoxy/Thiol-Ene Photopolymerization Technique

This study describes the synthesis of a curing agent derived from limonene as well as its application to prepare biobased thermoset polymers via the epoxy/thiol-ene photopolymerization (ETE) method. A biobased commercial epoxy resin was used to synthesize a crosslinked polymeric matrix of polyether-polythioether type. The preparation of the curing agent required two steps. First, a diamine intermediate was prepared by means of a thiol-ene coupling reaction between limonene and cysteamine hydrochloride. Second, the primary amino groups of the intermediate compound were alkylated using allyl bromide. The obtained ditertiary amine-functionalized limonene compound was purified and characterized by FTIR and NMR spectroscopies along with GC-MS. The curing agent was formulated with a tetrafunctional thiol in stoichiometric ratio, and a photoinitiator at 1 mol % concentration, as the components of a thiol-ene system (TES). Two formulations were prepared in which molar concentrations of 30 and 40 mol % of the TES were added to the epoxy resin. The kinetics of the ETE photopolymerizations were determined by means of Real-Time FTIR spectroscopy, which demonstrated high reactivity by observing photopolymerization rates in the range of 1.50–2.25 s−1 for the epoxy, double bonds and thiol groups. The obtained polymers were analyzed by thermal and thermo-mechanical techniques finding glass transition temperatures (Tg) of 60 °C and 52 °C for the polymers derived from the formulations with 30 mol % and 40 mol % of TES, respectively. Potential applications for these materials can be foreseen in the area of coatings

Efecto biológico de nanopartículas cargadas con ácido indolacético microbiano en parámetros morfométricos de tomate

The tomato is one of the vegetables that have the highest production worldwide, so for its fertilization and pest control products of synthetic origin are used, which affect the ecosystem where they are applied, for this reason biologically sustainable alternatives are sought. One of these alternatives is the use of microbial metabolism, an example of this is Botryodiplodia theobromae, a phytopathogenic fungus capable of producing phytohormones from its metabolism, such as indolacetic acid (IAA). However, exogenous application of this phytohormone exhibits accelerated degradation when in contact with environmental factors. An alternative to minimize this effect is encapsulation with the use of biopolymeric materials that have the ability to coat the phytohormone and at the same time allow to increase the effectiveness of the product. In this work, the encapsulation efficiency (EE) of IAAfrom microbial broth was evaluated by liquid fermentation of B. theobromaein alginate/chitosan nanoparticles (Np) (ALG/QS); as well as its biological effectiveness represented in morphological development patterns in tomato plants. The results showed that IAAwas produced from the microbial metabolism of Botryodiplodia theobromae, which once encapsulated reached an EE of 90%,as well as various particle sizes. Regarding the biological effectiveness in tomato plants, it was observed that the Np loaded with microbial broth and synthetic grade IAAshowed a significant difference in most of the morphological parameters evaluated compared to the absolute control. Therefore, nanosystems loaded with biostimulants are shown as a future alternative for the application of biostimulants in vegetables such as tomatoesEl tomate es una de las hortalizas que mayor producción tienen a nivel mundial, por lo que para su fertilización y control de plagas se utilizan productos de origen sintético, que afectan el ecosistema donde son aplicados, por esta razón se buscan alternativas biológicamente sustentables. Una de esas alternativas es el uso del metabolismo microbiano, ejemplo de esto es Botryodiplodia theobromae hongo fitopatógeno capaz de producir fitohormonas a partir de su metabolismo, como es el ácido indolacético (AIA). Sin embargo, la aplicación exógena esta fitohormona presenta una degradación acelerada al ponerse en contacto con factores ambientales. Una alternativa para minimizar este efecto es la encapsulación con el uso de materiales biopoliméricos que tengan la capacidad de recubrir la fitohormona y al mismo tiempo permitir aumentar la efectividad del producto. En este trabajo se evaluó la eficiencia de encapsulación (EE) del AIA procedente del caldo microbiano por fermentación líquida de B. theobromae en nanopartículas (Np) de alginato/quitosán (ALG/QS); así como, su efectividad biológica representada en patrones morfológicos de desarrollo en plantas de tomate. Los resultados demostraron, que a partir del metabolismo microbiano de Botryodiplodia theobromae se produjo AIA, el cual una vez encapsulado alcanzo una EE de 90%, así como diversos tamaños de partícula. En relación con la efectividad biológica en plantas de tomate se observó que las Np cargadas con caldo microbiano y AIA grado sintético presentaron diferencia significativa en la mayoría los parámetros morfológicos en comparación con el testigo. Por lo que los nanosistemas cargados con bioestimulates son una alternativa a futuro para la aplicación de bioestimulantes en hortalizas como el tomate

Cold plasma copolymer with antimicrobial activity deposited on three different substrates

Abstract A good strategy to prevent early deposition of bacteria that can form biofilms is the application of antimicrobial coatings to existing surfaces, however this field has been little explored and coatings are often non uniform in thickness. A homogeneous film of R-Carvone-Octadiene (ppCop) was deposited on different substrates (coverslip, minced coverslip and fabric) by cold plasma copolymerization to study the influence of the substrate on antimicrobial activity and show clues about the influence of octadiene on copolymerization. The ppCop showed better antimicrobial activity results on the substrate with higher effective contact area, highlighting the influence of this variable on antimicrobial activity. The ppCop deposited on minced coverslip showed an inhibition of E. coli and S. aureus bacteria by 48.69 ±0.08% and 49.31 ±0.58% respectively, with an average roughness of 14.1±0.02 nm and a static water contact angle of 79± 0.4°. The ppCop showed no cytotoxicity to the human cell line