First Steps in the Aggregation Process of Copolymers Based on Thymine Monomers: Characterization by Molecular Dynamics Simulations and Atomic Force Microscopy

GARAY, A. SERGIO; RODRIGUES, DANIEL E.; FUSELLI, ANTONELA; MARTINO, DÉBORA M.; PASSEGGI, MARIO C.G. (H)

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016 vol. 120 p. 3414 - 3424

1520-6106

p { margin-bottom: 3.53mm; direction: ltr; color: rgb(0, 0, 0); text-align: center; widows: 2; orphans: 2; }p.western { font-family: "Times","Times New Roman"; font-size: 20pt; font-weight: bold; }p.cjk { font-family: "Times New Roman",serif; font-size: 20pt; font-weight: bold; }p.ctl { font-family: "New York",serif; font-size: 20pt; font-weight: bold; }a:visited { color: rgb(128, 0, 128); }a.western:visited { }a.cjk:visited { }a.ctl:visited { }a:link { color: rgb(0, 0, 255); }AtomisticMolecular Dynamic simulations were performed to study the structureof isolated VBT-VBA (vinylbenzyl thymine - vinylbenzyltriethylammonium chloride) copolymer chains in water at differentmonomeric species ratios (1:1 and 1:4). The geometric parameters ofthe structure that the copolymers form in equilibrium together withthe basic interactions that stabilize them were determined. AtomicForce Microscopy (AFM) measurements of dried diluted concentrationsof the two copolymers onto Highly Oriented Pyrolytic Graphite (HOPG)substrates were carried out to study their aggregation arrangement.The experiments show that both copolymers arrange in fiber-likestructures. Comparing the diameters predicted by the simulationresults and those obtained by AFM it can be concluded that individualcopolymers arrange in bunches of two chains, stabilized bycontraions-copolymer interactions for the 1:1 copolymerization ratioat the ionic strength of our samples. In contrast, for the 1:4 systemthe individual copolymer chains do not aggregate in bunches. Theseresults remark the relevance of the copolymerization ratio and ionicstrength of the solvent in the mesoscopic structure of thesematerials.