Publicaciones 2011-2020

@article{RN1008,
title = {A Characterization Of Cellulose In Seven Books Using Raman Spectroscopy In The 800-1800 cm-1 Range.},
author = {J.S. Gomez-Jeria and S. Gutierrez and J. Surco-Luque and E. Clavijo and I. Reyes-Diaz},
url = {https://www.researchgate.net/publication/330521781_A_characterization_of_cellulose_in_seven_books_using_Raman_spectroscopy_in_the_800-1800_cm-1_range},
issn = {2455-8990},
year = {2019},
date = {2019-01-03},
journal = {Research Journal of Pharmaceutical, Biological and Chemical Sciences.},
volume = {10},
pages = {1565-1579},
publisher = {2010 RJPBCS},
abstract = {Raman spectroscopy was employed to study the non-printed area of a page of seven books printed in the 18th and 19th centuries. We employed the Vancouver Raman Algorithm to deal with the strong fluorescence background, obtaining spectra only in the 800 a 1800 cm-1 range. Two samples contain lignin, suggesting the presence of wood fibers. One sample (year 1799) contains only cellulose and gelatin. Two samples contain rosin. There are several Raman bands that we could not ascribe. Based on the results we propose a way to prepare the samples that could guarantee that the infrared and Raman spectra can be compared with confidence.},
keywords = {alum, carbonate, cellulose, gelatin, lignin, Paper composition, raman spectroscopy, rosin, sulfate, Vancouver Raman algorithm.},
pubstate = {published},
tppubtype = {article}
}

@article{RN150,
title = {Cooperative Association of P-Alkylbenzene Sulfonates Sodium Salts to Poly-2-(Dimethylamino) Ethylmethacrylate-N-Alkyl Quaternized at the Water/Chloroform Interface},
author = { H. Rios and X. Briones and M. Urz\'{u}a and V. Vargas},
url = {/brokenurl#<Go to ISI>://WOS:000313621900008},
doi = {10.1080/00222348.2012.716334},
issn = {0022-2348},
year = {2013},
date = {2013-01-01},
journal = {Journal of Macromolecular Science Part B-Physics},
volume = {52},
number = {4},
pages = {614-622},
abstract = {The association of p-alkyl benzene sulfonate sodium salts with several poly-2-(dimethylamino) ethylmethacrylate-N-alkyl quaternized bromides at the water/chloroform interface was studied. High association percentages were found which increase with both the size of the sulfonate molecule and the length of the polyelectrolyte side chain: octyl, decyl, dodecyl and tetradecyl. The results fit well to the Hill's equation for the association of anionic surfactant to polyelectrolytes. Benzene sulfonate shows an anticooperative behavior for the association, whereas 4-methyl benzene sulfonate and 4-ethylbenzene sulfonate are increasingly cooperative for the association. From the association constants, the standard free energies of transfer from water to the interfacial polyelectrolytes were determined. Their values were a linear function of the number of carbon atoms of the aliphatic residue of the benzene sulfonate molecule ranging from -15.7 kJ/mol of CH2 groups for the octyl polyelectrolyte to -18.9 kJ/mol of CH2 groups for the tetradecyl derivative. These values are similar to those reported for the association of some of these sulfonates molecules with ammonium type cationic micelles. The results for the incremental free energy of transfer by mol of methylene group from water to micelles are in the same order of magnitude as those reported for p-alkyl phenoxides and p-alkylbenzoates to hexadecyltrimethyl ammonium bromide micelles. The results shows that amphipathic counterions as small as 4-ethylbenzenesulfonate are enough to induce a cooperative effect in their association to cationic polyelectrolytes.},
keywords = {aqueous-solution, association, binding, chloride chloroform-water cooperative counterions, dextran dodecyltrimethylammonium effects, hydrophobic interactions, interface, ions, micelles, polyelectrolyte polyelectrolytes, sulfate, sulfonate surfactant water},
pubstate = {published},
tppubtype = {article}
}

@article{RN1_98,
title = {Adsorption Behavior of Hydrophobically Modified Polyelectrolytes onto Amino- or Methyl-Terminated Surfaces},
author = { X. Briones and M.V. Encinas and D.F.S. Petri and J. Pavez and R.A. Tapia and M. Yazdani-Pedram and M. Urz\'{u}a},
url = {/brokenurl#<Go to ISI>://WOS:000296598300017},
doi = {10.1021/la2025632},
issn = {0743-7463},
year = {2011},
date = {2011-01-01},
journal = {Langmuir},
volume = {27},
number = {22},
pages = {13524-13532},
abstract = {The adsorption of hydrophobically modified polyelectrolytes derived from poly(maleic anhydride-alt-styrene) (P(MA-alt-St)) containing in their side chain aryl-alkyl groups onto amino- or methyl-terminated silicon wafers was investigated. The effect of the spacer group, the chemical nature of the side chain, molecular weight of polyelectrolyte, and ionic strength of solution on the polyelectrolyte adsorbed amount was studied by null ellipsometry. The adsorbed amount of polyelectrolyte increased with increasing ionic strength, in agreement with the screening-enhanced adsorption regime, indicating that hydrophobic interactions with the surface play an important role in the adsorption process. At constant ionic strength, the adsorbed amount was slightly higher for polyelectrolytes with larger alkyl side chain and decreased with the hydrophobicity of aryl group. The adsorption behavior is discussed in terms of the side chain flexibility of the polymer. Characteristics of the adsorbed layer were studied by atomic force microscopy (AFM) and contact angle measurements. AFM images show the presence of aggregates and closed globular structure of polyelectrolyte onto the amino- or methyl-terminated surface, which agrees with a 3D and 2D growth mechanism, respectively. Fluorescence measurements showed that the aggregation of polyelectrolyte containing the hydrophobic naphthyl group occurs already in the solution. However, the aggregation of polyelectrolytes containing the phenyl group in its side chain is not observed in solution but is induced by the amino-terminated surface. This difference can be explained in terms of the higher flexibility of side chain bearing the phenyl group. The polyelectrolyte films showed a high chemical heterogeneity and moderate hydrophobicity.},
keywords = {anhydride), carboxymethyl cellulose, charge complexes, layers, silica, solid-surfaces, solvent, sulfate},
pubstate = {published},
tppubtype = {article}
}