Browsing by Author "Etxeberria, Agustin"
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Item Characterization of Comb Shaped MAA-co-PEGMA Copolymers Synthesized by Free-Radical Polymerization(2020-12) Emaldi, Iñaki; Agirre, Amaia; Etxeberria, Agustin; Erkizia, Edurne; Dolado, Jorge S.; Leiza, Jose R.; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNMethacrylic acid-co-polyethylene glycol methacrylate (MAA-co-PEGMA) copolymers (also known as MPEG-type polycarboxylate ether (PCE) superplasticizers) present comb-shaped microstructure and they are generally used as dispersants of inorganic particles in cementitious formulations. Application properties of the PCEs strongly depend on the molecular structure and therefore accurate characterization of the microstructure is necessary to fully understand the structure–property relationship. In this work, MAA-co-PEGMA copolymers with various lateral size chain lengths and homogeneous copolymer compositions are synthesized by starved-feed semibatch copolymerization. Molar mass and radius of gyration distributions and monomer sequence distribution are measured using size exclusion chromatography coupled with multi angle light scattering (SEC/MALS/refractive index, RI) and 1H and 13C NMR, respectively. Furthermore, it is proved that the experimental radius of gyration compares well with the prediction of a theoretical model for the radius of gyration that uses characteristic parameters of the microstructure of the PCEs (e.g., average molar masses). This confirms the accuracy of the measurements of the absolute molar masses for the MPEG-type PCEs synthesized by free-radical (co)polymerization.Item Modelling and control of the microstructure of comb-like poly(MAA-: Co-PEGMA) water-soluble copolymers(2019-02-28) Emaldi, Inãki; Hamzehlou, Shaghayegh; Erkizia, Edurne; Sanchez Dolado, Jorge; Etxeberria, Agustin; Leiza, Jose Ramon; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNWater-soluble copolymers of methacrylic acid and poly(ethylene glycol) methacrylate (poly(MAA-co-PEGMA)) present a comb like structure. These macromolecules under alkaline conditions present an anionic backbone and uncharged side chains. The control of their microstructure is of paramount importance for application as cementitious admixtures. With this in mind, open-loop control strategies including monomer starved and optimal addition policies were employed to obtain homogeneous composition copolymers. A detailed mathematical model was developed for the copolymerization of MAA and PEGMA5 and was used to develop optimal feeding strategies. The mathematical model provides a good representation of the experimental data sets and copolymers with desired homogeneous copolymer compositions were synthesized within the shortest possible reaction times.Item Organic-acid mediated bulk polymerization of ε-caprolactam and its copolymerization with ε-caprolactone(2016-08-01) Sanchez-Sanchez, Ana; Basterretxea, Andere; Mantione, Daniele; Etxeberria, Agustin; Elizetxea, Cristina; de la Calle, Amaia; García-Arrieta, Sonia; Sardon, Haritz; Mecerreyes, David; POLIMEROSPolyamides (PA) constitute one of the most important classes of polymeric materials and have gained strong position in different areas, such as textiles, fibers, and construction materials. Whereas most PA are synthesized by step-growth polycondensation, PA 6 is synthesized by ring opening polymerization (ROP) of ε-caprolactam (ε-CLa). The most popular ROP methods involve the use of alkaline metal catalyst difficult to handle at large scale. In this article, we propose the use of organic acids for the ROP of ε-CLa in bulk at 180 °C (below the polymer's melting point). Among evaluated organic acids, sulfonic acids were found to be the most effective for the polymerization of ε-CLa, being the Brønsted acid ionic liquid: 1-(4-sulfobutyl)−3-methylimidazolium hydrogen sulfate the most suitable due to its higher thermal stability. End-group analysis by 1H nuclear magnetic resonance and model reactions provided mechanistic insights and suggested that the catalytic activity of sulfonic acids was a function of not only the acid strength, but of the nucleophilic character of conjugate base as well. Finally, the ability of sulfonic acid to promote the copolymerization of ε-CLa and ε-caprolactone is demonstrated. As a result, poly(ε-caprolactam-co-ε-caprolactone) copolymers with considerably randomness are obtained. This benign route allows the synthesis of poly(ester amide)s with different thermal and mechanical properties.