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<p><font color="#ff0000">COMPUTATIONAL ENGINEERING OF CHOLESTERIC
COLLAGEN FILMS: RHEOLOGICAL PROPERTIES, HYDRODYNAMICS AND FILM
FORMATION</font><br>
<br>
<span style="white-space:nowrap">Lugar y fecha: Aula Magna, martes 23 de mayo a las 11:00 hs</span><br>
<br>
<span style="white-space:nowrap">Disertante: ALEJANDRO REY</span><br>
El profesor Alejandro Rey, originario de Argentina, es profesor en
la Universidad McGill desde 1988, y director del Grupo de
Investigación en Modelado de Materiales perteneciente al
Departamento de ingeniería<br>
Química de dicha universidad. Ha dictado cursos en nuestra
institución como profesor visitante en dos ocasiones en el marco
del subsidio Milstein del programa raíces, y actualmente se
encuentra visitando nuestra institución por tercera vez en el
marco el subsidio Milstein y del programa DOCTORAR.<br>
<br>
<span style="white-space:nowrap">Resumen:</span><br>
This seminar presents recent theory and simulation1-4 of the
formation of thin defect-free cholesteric collagen films by a
non-equilibrium self-assembly process that involves dilution,
flow-casting, and dehydration. To control and design defect-free
films an integrated quantitative understanding of all the
mechanisms that operate in the film formation are necessary. This
work uses a wide range of experimental information and
measurements that include phase diagrams, shear rheology, film
casting and drying to build a multi-transport computational model
of the entire process. The goal is to first identify all the
processing constraints and materials properties and then identify
the processing envelope that avoids microstructural defects and
leads to a perfect, chiral, collagen thin homogeneous film with a
nano-wrinkled surface. Rheological data are used to find molecular
aspect ratio, orientational diffusivity and flow-aligning
functions. Four roll flow kinematics is then used to identify the
required flow type and strength to align dilute collagen solutions
and form films with suitable initial structures. Finally , finely
tuned dehydration is shown to lead to defect-free films when the
time scale of chirality formation is in the proper ratio with the
water removal rate. The integrated model can be applied to other
cholesteric biomaterials such as nano-crystalline cellulose and
silk solutions.<br>
<br>
1. A.D. Rey, "Liquid Crystal Models of Biological Materials and
Processes”, Soft Matter, 6-5, 3402-3429, 2010.<br>
2. Echeverria, Coro, et al. "Two negative minima of the first
normal stress difference in a cellulose‐based cholesteric liquid
crystal: Helix uncoiling." Journal of Polymer Science Part B:
Polymer Physics 55.10 (2017): 821-830<br>
3.O. F. Aguilar Gutiérrez and A.D. Rey, "Theory and Simulation of
Cholesteric Film Formation Flows of Dilute Collagen Solutions",
Langmuir, 10.1021/acs.langmuir.6b0344, 32 (45), pp 11799–11812,
Oct 19, 2016.<br>
4.O. F. Aguilar Gutiérrez and A.D. Rey, "Geometric Reconstruction
of Biological Orthogonal Plywoods", Soft Matter, DOI:
10.1039/C5SM02214B, Nov 19, 2015, 12, pp 1184 - 1191, 2016.</p>
<br>
<pre class="moz-signature" cols="72">--
Dr. Ezequiel R. Soulé
División Polímeros Nanoestructurados - INTEMA
Facultad de Ingeniería, UNMdP
Av. Juan B. Justo 4302 - (7600) Mar del Plata,
Buenos Aires, Argentina
TE: (54-223) 481-6600 int 240</pre>
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