Nanocomposite of Fullerenes and Natural Rubbers: MARTINI Force Field Molecular Dynamics Simulations

Jiramate Kitjanon; Wasinee Khuntawee; Saree Phongphanphanee; Thana Sutthibutpong; Nattaporn Chattham; Mikko Karttunen; Jirasak Wong-Ekkabut

doi:10.3390/polym13224044

Nanocomposite of Fullerenes and Natural Rubbers: MARTINI Force Field Molecular Dynamics Simulations

Polymers (Basel). 2021 Nov 22;13(22):4044. doi: 10.3390/polym13224044.

Authors

Jiramate Kitjanon^{1

2}, Wasinee Khuntawee^{1

2

3}, Saree Phongphanphanee^{2

3

4}, Thana Sutthibutpong^{2

3

5}, Nattaporn Chattham¹, Mikko Karttunen^{6

7

8}, Jirasak Wong-Ekkabut^{1

2

3}

Affiliations

¹ Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
² Computational Biomodelling Laboratory for Agricultural Science and Technology (CBLAST), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
³ Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400, Thailand.
⁴ Department of Material Science, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
⁵ Department of Physics, Faculty of Science, King Mongkut's University of Technology Thonburi (KMUTT), Bangkok 10140, Thailand.
⁶ Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7, Canada.
⁷ Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7, Canada.
⁸ The Center for Advanced Materials and Biomaterials Research, The University of Western Ontario, London, ON N6A 3K7, Canada.

Abstract

The mechanical properties of natural rubber (NR) composites depend on many factors, including the filler loading, filler size, filler dispersion, and filler-rubber interfacial interactions. Thus, NR composites with nano-sized fillers have attracted a great deal of attention for improving properties such as stiffness, chemical resistance, and high wear resistance. Here, a coarse-grained (CG) model based on the MARTINI force field version 2.1 has been developed and deployed for simulations of cis-1,4-polyisoprene (cis-PI). The model shows qualitative and quantitative agreement with the experiments and atomistic simulations. Interestingly, only a 0.5% difference with respect to the experimental result of the glass transition temperature (T_g) of the cis-PI in the melts was observed. In addition, the mechanical and thermodynamical properties of the cis-PI-fullerene(C₆₀) composites were investigated. Coarse-grained molecular dynamics (MD) simulations of cis-PI-C₆₀ composites with varying fullerene concentrations (0-32 parts per hundred of rubber; phr) were performed over 200 microseconds. The structural, mechanical, and thermal properties of the composites were determined. The density, bulk modulus, thermal expansion, heat capacity, and T_g of the NR composites were found to increase with increasing C₆₀ concentration. The presence of C₆₀ resulted in a slight increasing of the end-to-end distance and radius of the gyration of the cis-PI chains. The contribution of C₆₀ and cis-PI interfacial interactions led to an enhancement of the bulk moduli of the composites. This model should be helpful in the investigations and design of effective fillers of NR-C₆₀ composites for improving their properties.

Keywords: MARTINI force field; cis-1,4-polyisoprene; molecular dynamics simulations; natural rubber.