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COARSE-GRAINED MC SIMULATIONS OF POLYMER NANOCOMPOSITES

Erguney, Fatih M
http://rave.ohiolink.edu/etdc/view?acc_num=akron1176404164

Abstract Details

2007, Doctor of Philosophy, University of Akron, Polymer Science.
A new generation of MC Simulations for dense melts of coarse-grained chains on a high coordination lattice has been developed so that the simulations incorporate nanoscale filler particles. In this unique approach, filler particles and matrix chains are built from the same chemical structural building unit. With this special construction method, pair wise enthalpic interactions between the two species are the same. A desired number of linear chains are collapsed to become nanoparticles. The collapse process is intramolecular in its origin and achieved by the enhancement of the attractive core of the discretized Lennard-Jones potential. Even when the nanoparticles are completely collapsed to dense, impermeable objects, they still have some degrees of freedom left in their internal structure. Hence, the translational motion of their centers of masses remains comparable in magnitude to that of the matrix chains. Degree of collapse of the filler particles can be manipulated by changing the magnitude of the enhancement in their attractive LJ potential. Therefore, it is also possible to create partially collapsed nanoparticles with moderate permeability against the matrix chains. Clustering of nanoparticles is normally not the case provided that they are strongly collapsed. Not similarly, weakly collapsed filler particles may show some spontaneous clustering behavior. However, this aggregation upon clustering is not due to energetic interactions, but is rather because of the reduction in the conformation entropy of the matrix chains when they fill the extra space provided by permeable filler particles. In this report, most efforts focus on the investigation the response of the mean square radius of gyration, „´s2„Äm, of the matrix chains to random arrays of the nanoscale filler particles. The changes in „´s2„Äm are targeted as a function of compactness, mobility, or composition of the nanoparticles. The relative size effects of matrix chains and filler particles are also of concern. In this simple model, a detailed description of surface - matrix interactions is missing. Nevertheless, the simulated response of „´s2„Äm to the insertion of the filler particles seems quite complicated and very much indeed system dependent. There exists a non-monotonic dependence on the extent of the collapse of the filler particles. The mobility and concentration of the filler particles, as well as the relative molecular masses of the two species, are determined to affect the resulting behavior. Distortion of the matrix chains is seen when the particles and the matrix chains are both represented by a relatively small number of beads. On the contrary, contraction of matrix chains may also be expected if the two species have sufficiently large molecular masses. In the former case, mobility of the filler particles is speculated to account for the unexpected behavior of the matrix chains, whereas the latter behavior is most probably favored by an entropic driving force appearing as a result of a huge gain in the conformation entropy when the matrix chains travel into to a confined geometry defined by the nanoparticles through nano channels in which the number of available configurations for the matrix chains is very limited.
Wayne Mattice (Advisor)
filler particles; matrix chains; filler; chains; POE; POE chains; particles

Recommended Citations

Citations

  • Erguney, F. M. (2007). COARSE-GRAINED MC SIMULATIONS OF POLYMER NANOCOMPOSITES [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1176404164

    APA Style (7th edition)

  • Erguney, Fatih. COARSE-GRAINED MC SIMULATIONS OF POLYMER NANOCOMPOSITES. 2007. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1176404164.

    MLA Style (8th edition)

  • Erguney, Fatih. "COARSE-GRAINED MC SIMULATIONS OF POLYMER NANOCOMPOSITES." Doctoral dissertation, University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1176404164

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.