Crystalline structure and thermotropic behavior of alkyltrimethylphosphonium amphiphiles

Quaternary organophosphonium salts bearing long alkyl chains are cationic surfactants of interest owing to their physical and biological properties. In the present work, the crystal structure and thermotropic behavior of the homologous series of alkyltrimethylphosphonium bromides (nATMP·Br), with the alkyl chain containing an even number (n) of carbon atoms from 12 to 22, have been examined within the 0–300 °C range of temperatures. These compounds were shown to be resistant to heat up to ~390 °C. The phases adopted at different temperatures were detected by DSC, and the structural changes involved in the phase transitions have been characterized by simultaneous WAXS and SAXS carried out in real-time, and by polarizing optical microscopy as well. Three or four phases were identified for n = 12 and 14 or n = 16, respectively, in agreement with the heat exchange peaks observed by DSC. The phase existing at room temperature (Ph-I) was found to be fully crystalline and its crystal lattice was determined by single-crystal X-ray diffraction methods. Ph-II consisted of a semicrystalline structure that can be categorized as Smectic-B with the crystallized ionic pairs hexagonally arranged in layers and the molten alkyl chain confined in the interlayer space. Ph-II of 12ATMP·Br and 14ATMP·Br directly isotropicized upon heating at ~220 °C, whereas for n = 16, it converted into a Smectic-A phase (Ph-III) that needed to be heated above ~240 °C to become isotropic (Ph-Is). The correlation existing between the thermal behavior, phase structure and length of the alkyl side chain has been demonstrated.Peer ReviewedPostprint (published version

Elastomeric copolyesters of omega-pentadecalactone and cyclohexylenedimethylene succinate obtained by enzymatic polymerization

The use of renewable monomers and green polymerization processes for preparing new synthetic polymers is a hot topic today. In this work we have obtained high molecular weight copolyesters derived from ¿-pentadecalactone (PDL), dimethyl succinate (DMS) and 1,4-cyclohexanedimethanol (1,4-CHDM) by a combination of ring opening polymerization (ROP) and two step melt polycondensation processes. The reaction has been carried in bulk under mild conditions (80–120 ¿C) and catalyzed by immobilized Candida artarctica lipase B (N435 biocatalyst). These reactions were followed by 1 H NMR and it was observed that although PDL reacted faster, at the end copolyesters displayed a random microstructure due to transesterification reactions taking place during polymerization. These copolyesters were thermally stable up to around 350 ¿C and semicrystalline for all compositions with melting temperatures decreasing with the increased content of the counterpart comonomer up to a pseudo-eutectic point located at 40 mol-% of PDL composition. The crystalline structure and transitions taken place by heating have been studied by WAXS and SAXS synchrotron X-ray diffraction. Copolyesters with elastomeric properties could be obtained at intermediate compositions.Peer ReviewedObjectius de Desenvolupament Sostenible::13 - Acció per al ClimaObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Ionic coupling of hyaluronic acid with ethyl N-lauroyl L-arginate (LAE): Structure, properties and biocide activity of complexes

Ethyl alpha-N-lauroyl L-arginate hydrochloride (LAE) was coupled with hyaluronic acid (HyA) 2 to form ionic complexes with LAE to HyA ratios of 1:1 and 1:2. The complexes were extensively 3 characterized by FTIR and NMR spectroscopies and their thermal properties evaluated by 4 thermogravimetry and calorimetry. Thin films prepared from these complexes by casting 5 displayed a smectic-like structure based on an ordered arrangement of LAE and HyA layers 6 with a nanometric periodicity of 3.8-3.9 nm. Films immersed in water at pH 7.4 and 5.5 7 dissociated to deliver free LAE to the environment and reaching the equilibrium in few hours. 8 The biocide activity of these films against both Gram-positive and Gram-negative bacteria was 9 preliminary assessed by the liquid medium method, and shown to be notable in both cases. The 10 antibacterial property of the complexes was found to increase with the content of LAE and to be 11 particularly efficient against Gram-negative S. enterica bacteria.Peer ReviewedPostprint (author's final draft

Activitats de difusió científica i tecnològica de l'ETSEIB:

És una pràctica de laboratori químic que forma part d'un conjunt d'activitats que l'ETSEIB oferta als instituts de secundaria. La finalitat és que els estudiants de batxillerat coneguin l'ETSEIB a la vegada que completen la seva formacióPreprin

Activitats de difusió científica i tecnològica de l'ETSEIB: "Separació i identificació dels colorants del recobriment de caramels de xocolata"

És una pràctica de laboratori químic que forma part d'un conjunt d'activitats que l'ETSEIB oferta als instituts de secundaria. La finalitat és que els estudiants de batxillerat coneguin l'ETSEIB a la vegada que completen la seva formaci

Activitats de difusió científica i tecnològica de l'ETSEIB: "Separació i identificació dels colorants del recobriment de caramels de xocolata"

És una pràctica de laboratori químic que forma part d'un conjunt d'activitats que l'ETSEIB oferta als instituts de secundaria. La finalitat és que els estudiants de batxillerat coneguin l'ETSEIB a la vegada que completen la seva formaci

Activitats de difusió científica i tecnològica de l'ETSEIB: "Separació i identificació dels colorants del recobriment de caramels de xocolata"

És una pràctica de laboratori químic que forma part d'un conjunt d'activitats que l'ETSEIB oferta als instituts de secundaria. La finalitat és que els estudiants de batxillerat coneguin l'ETSEIB a la vegada que completen la seva formacióPreprin

Activitats de difusió científica i tecnològica de l'ETSEIB:

És una pràctica de laboratori químic que forma part d'un conjunt d'activitats que l'ETSEIB oferta als instituts de secundaria. La finalitat és que els estudiants de batxillerat coneguin l'ETSEIB a la vegada que completen la seva formaci

DNA coiled coil superstructures in oligonucleotide crystals

We present the structure of coiled coils found in two oligonucleotide DNA crystals. The sequences d-(ATATATATAT) and d(CGATATATAT) are used. In the first case several coiled coils with different structures are found. In the second case a single structure is present. The results are compared with other coiled coil structures. They might be used in the development of new nanomaterials.Peer ReviewedPostprint (published version

DNA coiled coil superstructures in oligonucleotide crystals

We present the structure of coiled coils found in two oligonucleotide DNA crystals. The sequences d-(ATATATATAT) and d(CGATATATAT) are used. In the first case several coiled coils with different structures are found. In the second case a single structure is present. The results are compared with other coiled coil structures. They might be used in the development of new nanomaterials.Peer Reviewe