Elaboración de copolímeros termoconmutables y funcionalizados a partir de 2-oxazolinas
Date
2019-11-26
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Pontificia Universidad Católica del Perú
Abstract
Esta tesis trata de la síntesis de poli [2-oxazolina]s termosensibles y funcionalizadas a partir de 2-isopropil-2-oxazolina, 2-ciclopropil-2-oxazolina, 2-(3-butenil)-2-oxazolina (vinil-oxazolina) y 3-(oxazol-2-il) propionato de metilo (éster-oxazolina), mediante polimerización catiónica por apertura de anillo (CROP). Los espectros 1H, 13C-RMN y FT-IR de los polímeros demuestran la formación de las estructuras poliméricas planeadas en cada caso y permiten el cálculo de los grados de polimerización y el porcentaje molar de sus meros. Las medidas turbidimétricas muestran que los copolímeros poli [2-ciclopropil-2-oxazolina-st-2-carboxietil-2-oxazolina] son sensibles a la temperatura y al pH debido a sus grupos ionizables ácido carboxílico. Dichos polímeros muestran una temperatura de transición conformacional cercana a la temperatura corporal humana (~ 37 ºC) a valores de pH bajos, así que presentan potencial aplicación en el desarrollo de biomateriales, pues copolímeros de este tipo presentan autoagregación en medio acuoso, según la literatura. Los copolímeros poli [2-ciclopropil-2-oxazolina-st-vinil-oxazolina] muestran sensibilidad a la temperatura y solubilidad en agua a temperatura ambiente, excepto aquel con mayor contenido porcentual de meros vinil-oxazolina (35 %). Es factible sintetizar un hidrogel basado en el copolímero poli [2-ciclopropil-2-oxazolina-st-vinil-oxazolina] y N-isopropilacrilamida a temperatura ambiente, en una mezcla de agua-acetonitrilo y en presencia de un fotoiniciador bajo irradiación con luz. Dicho hidrogel presenta un grado de absorción de 4 g de agua/g gel seco. La inserción de unidades hidrofóbicas vinil-oxazolina en polímeros con sensibilidad al pH y a la temperatura permitiría la estabilización de micelas o vesículas en medio acuoso, ya que se podrían fotoentrecruzar para fijar dichas estructuras permanentemente bajo condiciones de temperatura y pH previamente establecidas. Finalmente, el análisis de TGA-DSC de los copolímeros poli[2-ciclopropil-2-oxazolina-st-2-carboxietil-2-oxazolina] muestra que un contenido cada vez mayor de grupos ácido carboxílico incrementa la estabilidad térmica, al mismo tiempo que disminuye la movilidad de las cadenas poliméricas debido al incremento de enlaces de hidrógeno entre los grupos ácido carboxílico y grupos amida.
This thesis consists on synthesis of thermosensitive and functionalized poly[2-oxazoline]s based on 2-isopropyl-2-oxazoline, 2-cyclopropyl-2-oxazoline, 2-(3-butenyl)-2-oxazoline (vinyl-oxazoline) and methyl 3-(oxazol-2-yl) propionate (ester-oxazoline), by means of cationic ring-opening polymerization (CROP). The 1H, 13C-NMR and FT-IR spectra of polymers demonstrate formation of planned polymeric frameworks and allow to calculate the degree of polymerization, as well as molar percentage of meres for each polymer. Turbidimetric measurements show that copolymers poly[2-cyclopropyl-2-oxazoline-st-2-carboxyethyl-2-oxazoline] are bisensitive to temperature and pH due to ionizable carboxylic acid groups. These polymers show a conformational transition temperature nearby to human body temperature (~ 37 ºC) at low pH values, so that they have potential application for developing biomaterials, since this kind of copolymers are capable of autoaggregation in aqueous environment, as it is mentioned in the literature. Copolymers poly[2-cyclopropyl-2-oxazoline-st-vinyl-oxazoline] show thermosensitiveness and solubility in water at room temperature, except that one with more content of vinyl-oxazoline meres (35 %). It is feasible synthesizing a hydrogel based on the copolymer poly[2-cyclopropyl-2-oxazoline-st-vinyl-oxazoline] and N-isopropylacrilamide at room temperature, both dissolved into a mixture of water-acetonitrile in presence of a photoinitiator under irradiation with light. Such hydrogel shows a degree of swelling of 4 g of water/g dried gel. Insertion of hydrophobic units of vinyl-oxazoline into polymers with sensitiveness to pH and temperature would allow to stabilize micelles or vesicles in aqueous environment, since they will be able to be photocrosslinked in order to permanently fix such aggregates under previously stablished temperature and pH conditions. Finally, TGA-DSC analysis of copolymers poly[2-cyclopropyl-2-oxazoline-st-2-carboxyethyl-2-oxazoline] show that an increasing content of carboxylic acid groups improves thermal stability and, at the same time, mobility of polymeric chains decreases due to increasing hydrogen bonds among carboxylic acid and amide groups.
This thesis consists on synthesis of thermosensitive and functionalized poly[2-oxazoline]s based on 2-isopropyl-2-oxazoline, 2-cyclopropyl-2-oxazoline, 2-(3-butenyl)-2-oxazoline (vinyl-oxazoline) and methyl 3-(oxazol-2-yl) propionate (ester-oxazoline), by means of cationic ring-opening polymerization (CROP). The 1H, 13C-NMR and FT-IR spectra of polymers demonstrate formation of planned polymeric frameworks and allow to calculate the degree of polymerization, as well as molar percentage of meres for each polymer. Turbidimetric measurements show that copolymers poly[2-cyclopropyl-2-oxazoline-st-2-carboxyethyl-2-oxazoline] are bisensitive to temperature and pH due to ionizable carboxylic acid groups. These polymers show a conformational transition temperature nearby to human body temperature (~ 37 ºC) at low pH values, so that they have potential application for developing biomaterials, since this kind of copolymers are capable of autoaggregation in aqueous environment, as it is mentioned in the literature. Copolymers poly[2-cyclopropyl-2-oxazoline-st-vinyl-oxazoline] show thermosensitiveness and solubility in water at room temperature, except that one with more content of vinyl-oxazoline meres (35 %). It is feasible synthesizing a hydrogel based on the copolymer poly[2-cyclopropyl-2-oxazoline-st-vinyl-oxazoline] and N-isopropylacrilamide at room temperature, both dissolved into a mixture of water-acetonitrile in presence of a photoinitiator under irradiation with light. Such hydrogel shows a degree of swelling of 4 g of water/g dried gel. Insertion of hydrophobic units of vinyl-oxazoline into polymers with sensitiveness to pH and temperature would allow to stabilize micelles or vesicles in aqueous environment, since they will be able to be photocrosslinked in order to permanently fix such aggregates under previously stablished temperature and pH conditions. Finally, TGA-DSC analysis of copolymers poly[2-cyclopropyl-2-oxazoline-st-2-carboxyethyl-2-oxazoline] show that an increasing content of carboxylic acid groups improves thermal stability and, at the same time, mobility of polymeric chains decreases due to increasing hydrogen bonds among carboxylic acid and amide groups.
Description
Keywords
Polímeros, Polimerización
Citation
Collections
Endorsement
Review
Supplemented By
Referenced By
Creative Commons license
Except where otherwised noted, this item's license is described as info:eu-repo/semantics/openAccess