Molecular Simulation of Polymer-Carbon Nanotube Interactions

1. Molecular Simulation of Polymer-Carbon Nanotube Interactions Under the guidance of Prof. Ajay S Panwar Aftabuddin Shaikh 123110001

2. Outline

3. Background Sumio Iijima ‘1991’ Discovered Carbon Nanotubes (CNTs) Nature 354 (1991) • Exceptional mechanical, electrical, thermal and optical properties of CNT • CNT in Polymer matrix • large surface area • low density • high aspect ratio (l/d)

4. Important Issues Properties of CNT – Polymer matrix depends not only on properties of CNT and Polymer matrix but also depend on other factors Uniform dispersion of CNTs Alignment of CNTs Preferential migration Adsorption EA PA F. Tao et al., Polymer 52 (2011)

5. Agglomeration of SWCNT (a) and MWCNT (b) Maaet al. Composites: Part A 41 (2012) Alignment of CNTs in Polymer matrix using electric field Park et al. Journal of Polymer Science: Polymer Physics44 (2006)

6. CNT-Polymer Interaction Interaction governs the properties of CNT-Polymer composites Types Covalent Non - Covalent Measuring & Characterization of Interfacial Interaction Wetting Atomic Force Microscopy (AFM) Microscopy

7. Molecular Simulation Why “SIMULATION”? Experiments  interfacial properties Physical Model  Mathematical Model Mathematical model – predict system behaviour for wide range of conditions But sometimes, Mathematical models  difficult to solve

8. Experiment, Theory and Simulation Theory Compare Test of Theory Model Compare Computer Simulation Compare Perform experiment Real Problems Test of Model Compare

9. Computer Simulation Atomistic Simulation Continuum Simulation A computer-generated cross section of the polymer-coated carbon nanotube. The polymer shell (blue) wraps around a semiconducting single-walled carbon nanotube (red) STANFORD UNIVERSITY GM Odegardet al. Composites Science and Technology 63 (2003)

10. Molecular Modelling Atoms & Molecules Real System Modelled Empirical Model Quantum Mechanical Model Bond Stretching Bond bending • Electrons • Nuclei • Atoms Non Bonded Interaction Van der Waals

11. Molecular Dynamics (MD) Simulation Classical Mechanics in Molecular SystemHOW? Thermal de Broglie wavelength de Broglie wavelength The evolution of the system in time is computed by solving the equations of motion for all system particles Lecture notes, Introduction to modelling and simulation, Prof. Markus Buehler, MIT

12. Some studies MEH-PPV & SWCNT MDMO-PPV & SWCNT P3HT & SWCNT Zaminpayma and Mirabbaszadeh, Computational Materials Science 58 (2012)

13. Contd… Interfacial vdW energy of PE-CNT composite (b) Young’s modulus of PE-CNT composite C Wei, Applied Physics Letters 88 (2006)

14. Monte Carlo (MC) Simulation Involve random numbers and probability statistics Obtain configuration of system at N different points Calculate the properties • Based on dependence on time, • Metropolis MC • Kinetic MC Wikipedia

15. MC Simulation for CNT – Polymer Interaction Random configuration from previous configuration MC Simulation Change in energy a. Radial distribution of polymer around CNT b. Polymer – Particle interaction force Zhang and Archer, Journal of Chemical Physics 121 (2004)

16. Conclusion • Factors like uniform dispersion, alignment of CNTs in polymer matrix, preferential migration and adsorption of polymer on CNT degrade the CNT-Polymer composite properties. • Experimental techniques like wetting, AFM, SEM etc. are used for interfacial characterization. • Molecular modelling and simulation is also used for understanding interfacial interaction. • Molecular modelling is done either by quantum mechanical method or by empirical method. • Molecular dynamics and Monte Carlo is used for simulating interfacial interaction.

17. Future Work Computational Method algorithm development better empirical models link quantum mechanical model and empirical model Fabrication Methods methods which can increase the bonding chemical which can increase the interaction between CNT and Polymer matrix But chemical should not degrade the property of the composite

18. Thank You