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Agglomeration Dynamics In Thermo-Sensitive Polymers Across The Lower Critical Solution Temperature: A Molecular Dynamics Simulation Study

Published online by Cambridge University Press:  03 February 2012

Sanket A. Deshmukh ,
Subramanian K.R.S. Sankaranarayanan  and
Derrick C. Mancini
Sanket A. Deshmukh
Affiliation:
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439
Subramanian K.R.S. Sankaranarayanan
Affiliation:
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439
Derrick C. Mancini
Affiliation:
Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439
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Abstract

Poly(N-isopropylacrylamide) (PNIPAM), a classic thermo-sensitive polymer, has a lower critical solution temperature (LCST) at ∼32°C. In this work we have used molecular dynamics simulations to understand the origin of the LCST and agglomeration of PNIPAM chains of 5 and 30 monomer units (5-mer and 30-mer). Experimentally, when the concentration of PNIPAM is >1 ppm, polymer chains after undergoing coil-to-globule transition above the LCST aggregates to yield a stable colloidal dispersion.In our study two PNIPAM chains, consisting of 30 monomer units each, were placed in a cubic simulation cell and were subsequently solvated. Simulations were carried out below and above the LCST, namely at 278 and 310K for 10ns. Simulated trajectories were analyzed for structural and dynamical properties of both PNIPAM and water. We observe coil-to-globule transition in PNIPAM above the LCST. We also find that the PNIPAM chains agglomerate above the LCST. We also observe entanglement in PNIPAM chains below the LCST. We also study agglomeration of 5 PNIPAM chains each consisting of 5 monomer units. There was no significant difference in polymer agglomeration behavior across the LCST for these short chain oligomers. The agglomeration behavior is thus strongly correlated to the size of the polymer chains. These results provide fundamental insight into the atomistic scale mechanism of PNIPAM agglomeration across the LCST.

Keywords

polymerbiomedicalsimulation
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1418: Symposium LL/MM – Gels and Biomedical Materials , 2012 , mrsf11-1418-ll07-06
Copyright
Copyright © Materials Research Society 2012

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References

REFERENCES

[1]Granick, S. and Rubinstein, M., “ Polymers: A multitude of macromolecules,” Nature Materials, vol. 3, pp. 586–587, 2004.10.1038/nmat1199CrossRefGoogle ScholarPubMed
[2]Briber, Robert M., Liu, Xiaodu, and Bauer, B. J., “The Collapse of Free Polymer Chains in a Network” Science, vol. 268, pp. 395–397, 1995.CrossRefGoogle ScholarPubMed
[3]Wu, Chi and Wang, X., “Globule-to-Coil Transition of a Single Homopolymer Chain in Solution,” Physical Review Letters, vol. 80, pp. 4092–4094, 1998.CrossRefGoogle Scholar
[4]Li, Z., Kyeremateng, S. O., Fuchise, K., Kakuchi, R., Sakai, R., Kakuchi, T., and Kressler, J. r.*, “Aggregation Behavior of Poly(N-isopropylacrylamide) Semitelechelics with a Perfluoroalkyl Segment in Water,” Macromolecular Chemistry and Physics, vol. 210, pp. 2138–2147, 2009.10.1002/macp.200900334CrossRefGoogle Scholar
[5]Lai, H. and Wu, P., “A infrared spectroscopic study on the mechanism of temperature-induced phase transition of concentrated aqueous solutions of poly(N-isopropylacrylamide) and N-isopropylpropionamide,” Polymer, vol. 51, pp. 1404–1412, 2010.CrossRefGoogle Scholar
[6]Geukens, B., Meersman, F., and Nies, E., “Phase Behavior of N-(Isopropyl)propionamide in Aqueous Solution and Changes in Hydration Observed by FTIR Spectroscopy,” The Journal of Physical Chemistry B, vol. 112, pp. 4474–4477, 2008.CrossRefGoogle Scholar
[7]Afroze, F., Nies, E., and Berghmans, H., “Phase transitions in the system poly(N-isopropylacrylamide)/water and swelling behaviour of the corresponding networks,” Journal of Molecular Structure, vol. 554, pp. 55–68, 2000.CrossRefGoogle Scholar
[8]Wu, C. and Zhou, S., “Thermodynamically Stable Globule State of a Single Poly(Wisopropylacry1amide)Chain in Water,” Macromolecules, vol. 28, pp. 5388–5390, 1995.CrossRefGoogle Scholar
[9]Sun, H., “Ab Initio Calculations and Force Field Development for Computer Simulation of Polysilanes,” Macromolecules, vol. 28, pp. 701–712, 1995.10.1021/ma00107a006CrossRefGoogle Scholar
[10]Knopp, B., Suter, U. W., and Gusev, A. A., “Atomistically Modeling the Chemical Potential of Small Molecules in Dense Polymer Microstructures. 1. Method,” Macromolecules, vol. 30, pp. 6107–6113, 1997.CrossRefGoogle Scholar
[11]Fritz, L. and Hofmann, D., “Molecular dynamics simulations of the transport of water-ethanol mixtures through polydimethylsiloxane membranes,” Polymer, vol. 38, pp. 1035–1045, 1997.CrossRefGoogle Scholar
[12]Ahmed, Z., Gooding, E., Pimenov, K., Wang, L., and Asher, S., “UV Resonance Raman Determination of Molecular Mechanism of Poly(N-isopropylacrylamide) Volume Phase Transition,” Journal of Physical Chemistry B, vol. 113, pp. 4248–4256, 2009.CrossRefGoogle ScholarPubMed