Santiago, D.; de la Flor, S.; Ferrando, F.; Ramis, X.; Sangermano, M. Macromolecular chemistry and physics Vol. 217, num. 1, p. 39-50 DOI: 10.1002/macp.201500261 Data de publicació: 2016-01 Article en revista
A series of acrylate-based shape-memory materials are synthesized from bisphenol A diacrylate monomers as crosslinking agents. Networks are synthesized by keeping constant the content of bisphenol A-based crosslinking agent and systematically varying the content ratio of different monofunctional chain builder monomers. The implications of the structure of bisphenol A-based monomers and the chemical structure and content of monofunctional monomers on thermomechanical properties are discussed. Thermomechanical properties are analyzed using dynamic mechanical analyses and mechanical properties are studied at room temperature and at the onset of the glass transition temperature. Shape-memory performances under isothermal and transient temperature conditions are also carried out. Tensile tests show excellent values of stress at break up to 45 and 15 MPa at room and high temperature, respectively. The measurements show excellent shape recovery and shape fixity ratios, ˜95% and 97%, respectively. These materials also show very high recovery velocities under transient temperature conditions, up to 24% min-1, and very short recovery times, up to 1.5 s, under isothermal conditions in a water bath. The results confirm that networks synthesized from bisphenol A crosslinkers are promising shape-memory materials.
The use of NMR spectroscopy in solution to investigate the chemical structure of engineering poly(alkylene terephthalate)s such as poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT) is reviewed. Chemical defects present in the polyester chain, such as oxydialkylene units, as well as accompanying side products such as cyclic oligomers generated in the polycondensation, are well detected in 1H NMR spectra. The technique is also demonstrated to be effective for identifying, and even for quantifying in certain cases, the end groups of these polyterephthalates, including those that are generated in small amounts as a consequence of thermal degradation. The application of NMR to the study of the chemical microstructure of copolyesters derived from such polyterephthalates is also reviewed for its unique ability to determine comonomeric sequence lengths and degree of randomness (R). Copolyesters synthesized by either melt polycondensation or entropically driven ring opening polymerization, in addition to those prepared by solid-state modification or melt blending, are the object of this review.
Japu, C.; Martinez de Ilarduya, A.; Alla, A.; García-Martín, M.G.; Galbis, J.; Muñoz, S. Macromolecular chemistry and physics Vol. 215, num. 21, p. 2048-2059 DOI: 10.1002/macp.201400299 Data de publicació: 2014-11-01 Article en revista
A set of copolyesters (PHTxGluxy) with compositions ranging between 90/10 and 50/50 in addition to the parent homopolyesters poly(hexamethylene terephthalate) (PHT) and PHGlux, are prepared by the melt polycondensation of 1,6-hexanediol (HD) with mixtures of dimethyl terephthalate (DMT) and dimethyl 2,4:3,5-di-O-methylene-d-glucarate (Glux). The copolyesters have inline image in the 35 000–45 000 g mol-1 range, their microstructure is random, and they start to decompose at a temperature well above 300 °C. Crystallinity of PHT is repressed by copolymerization so that copolyesters containing more than 20% of sugar-based units are essentially amorphous. On the contrary, PHTxGluxy displays a Tg that increases monotonically with composition from 16 °C in PHT up to 73 °C in PHGlux. Compared with PHT, the copolyesters show an accentuated susceptibility to hydrolysis and are sensitive to the action of lipases upon incubation under physiological conditions. The degradability of PHTxGluxy increases with the content in Glux units.
Lanz, A.; Garcia, M.; Portilla, J.A.; Martinez de Ilarduya, A.; Holler, E.; Ljubimova, J.; Muñoz, S. Macromolecular chemistry and physics Vol. 213, num. 15, p. 1623-1631 DOI: 10.1002/macp.201200134 Data de publicació: 2012-08-14 Article en revista
Microbial poly( β , L -malic acid) was modifi ed with either L -leucine ethyl ester (L) or L -phenylalanine
methyl ester (F) to produce amphiphylic copolymers. The degradation of these copolymers
in aqueous buffer took place under physiological conditions in a few weeks by hydrolysis
of the side chain ester group followed by cleavage of the
main chain. Spherical nanoparticles with diameters ranging
between 70 and 230 nm were prepared from these copolymers
by the dialysis-precipitation method. No alteration of the cell
viability was observed after incubation of these nanoparticles
in different cell lines. Anticancer drugs temozolomide and
doxorubicin were encapsulated in the nanoparticles. Temozolomide
was released within several hours whereas doxorubicin
took several weeks to be completely liberated.
Morell, M.; Fernandez-Francos, X.; Ramis, X.; Serra, À. Macromolecular chemistry and physics Vol. 211, num. 17, p. 1879-1889 DOI: 10.1002/macp.201000152 Data de publicació: 2010-09-01 Article en revista
Aradilla, D.; Estrany, F.; Armelin, E.; Oliver, R.; Iribarren, J.; Aleman, C. Macromolecular chemistry and physics Vol. 211, num. 15, p. 1663-1672 DOI: 10.1002/macp.201000015 Data de publicació: 2010-08-02 Article en revista
Teixeira-Dias, Bruno; Zanuy, D.; del Valle, LJ.; Estrany, F.; Armelin, E.; Aleman, C. Macromolecular chemistry and physics Vol. 211, num. 10, p. 1117-1126 DOI: 10.1002/macp.200900599 Data de publicació: 2010-05-17 Article en revista
The influence of the doping level in the formation of specific interactions between plasmid DNA and PEDOT is investigated using experimental assays and theoretical calculations. Electrochemical methods are used to prepare polymer samples with oxidation degrees ranging from 0.14 to 1.05 positive charges per repeating unit. A combination of experimental and theoretical
results are used to propose a mechanism for
the formation of DNA/conducting polymer complexes, which consists of the initial stabilization of the adducts through non-specific interactions followed by small structural re-arrangements that allow to be established specific hydrogen bonds involving the polar groups of the conducting
polymer and selected DNA bases.
Vitrification during the isothermal cure of a thermoset, which is monitored by dynamic
techniques such as temperature-modulated differential scanning calorimetry (TMDSC) or dielectric analysis (DEA), is analyzed in terms of its dependence on frequency. A simulation was used to obtain the vitrification time as a function of frequency, considering it as the time when the (frequency-dependent) glass transition temperature, Tg, of the curing system reaches the cure temperature. Simulations were carried out at different cure temperatures.
Other parameters, such as the exponents (reaction orders) in the Kamal equation, l in the DiBenedetto equation (controlling the dependence of Tg on the degree of cure), and the activation energy for the frequency dependence of Tg, were also considered. The results are compared with those obtained experimentally by a TMDSC technique at low frequencies and by DEA at high frequencies.
From the simulations it is found that the vitrification time decreases nonlinearly with log(frequency) in the low frequency range but approaches a linear dependence at high frequencies, in agreement with experimental data.
Izursun, I.; Bou, J. J.; Pérez, G.; Pérez-Camero, G.; Abad, C.; Campos, A.; Muñoz, S. Macromolecular chemistry and physics Vol. 202, num. 17, p. 3253-3256 Data de publicació: 2001-09 Article en revista
Völcker, N.; Klee, D.; Hanna, M.; Höcker, H.; Bou, J. J.; Martinez de Ilarduya, A.; Muñoz, S. Macromolecular chemistry and physics Vol. 200, num. 6, p. 1363-1373 Data de publicació: 1999-06 Article en revista