the degree of polymerization, surface roughness, and interactive energy impact polymer adsorption

Aquil Frost, Environmental Engineering, Central State University Graduate Student Mentor: Abishek VenkatakrishnanJohn Lewnard, Mechanical Engineering, University of Cincinnati Faculty Mentors: Dr. Kelly Anderson and Dr. Vikram KuppaAnne Shim, Biomedical Engineering, The Ohio State University

The Degree of Polymerization, Surface Roughness, and Interactive Energy Impact Polymer Adsorption

Introduction• Polymer adsorption onto surfaces is an important process in many applications of products such as

adhesives, paints, and plastics.• Simulations have been run to study the adsorption of polymers onto completely smooth surfaces,

though all surfaces are rough on the nano-scale.• The goal of this research is to find whether the degree of polymerization, surface roughness,

and/or interactive energy effect polymer adsorption in order to better explain the macro-scale properties of polymer adsorption.

Method

Conclusions

Acknowledgements

Results

Polymer Generation using C Surface Generation using MATLAB

Run Simulations using LAMMPS and VMD(Large-Scale Atomic/Molecular Massively Parallel Simulator and Visual Molecular Dynamics

Analyze Simulations

Controlled Variables• Polymer bond length• Polymer bond angle• Polymer density• Surface bond length• Ratio of surface atoms to surface

area• Amplitude of surface

We would like to thank the University of Cincinnati, in conjunction with the National Science Foundation, for funding this program. We would also like to thank our faculty mentors and graduate student mentor for their guidance and support.

Degree of Polymerization Surface Roughness Interactive Energy

0.0 10.420.931.341.752.262.673.183.593.90

0.05

0.1

0.15

0.2

0.25

Distance from Surface (Å)

Den

sity

of P

olym

ers (

g/cc

)

Short Polymer

Long Polymer

0.0 12.925.838.751.664.577.390.20

0.05

0.1

0.15

0.2

0.25

Distance from Surface (Å)

Den

sity

of P

olym

ers (

g/cc

)

Density of Short and Long Polymers on Surface A

Short Polymer

Long Polymer

Density of Short and Long Polymers on Surface B

Independent Variables• Degree of polymerization• Wavelength of surface• Interactive energy parameter

Dependent Variables• Degree of adsorption, measured

by the polymer’s distance from the surface

• Density profile compiled for each polymer-surface system• Average center of mass calculated for each chain length in each polymer-surface system• Polymer lengths, surface types, and interactive energies compared to find adhesion properties

• With high degree of polymerization : increased surface roughness caused decreased adsorption. • With low degree of polymerization : increased surface roughness caused increased adsorption.

• With high surface roughness: increased degree of polymerization caused decreased adsorption. • With low surface roughness: increased degree of polymerization caused increased adsorption.

• Increasing the interactive energy parameter caused increased adsorption universally.

Figure 1: Generated polymersShort Polymers: 42.5625 monomers per chainLong Polymers: 127.6875 monomers per chain

Figure 4: Polymer adsorption onto a sinusoidal surface

Figure 5: Density profile for surface A

Figure 6: Density profile for surface B

0.0 10.420.931.341.752.262.673.183.593.90

0.05

0.1

0.15

0.2

0.25

Distance from Surface (Å)

Den

sity

of P

olym

ers (

g/cc

)

Density of Short Polymers on Surface A and Surface B

Figure 7: Density profile for short polymers

Surface A

Surface B

0.0 10.420.931.341.752.262.673.183.593.90

0.020.040.060.08

0.10.120.140.160.18

0.2

Distance from Surface (Å)

Den

sity

of P

olym

ers (

g/cc

)

Density of Long Polymers on Surface A and Surface B

Figure 8: Density profile for long polymers

Surface A

Surface B

Figure 2: Surface AAmplitude: 5 ÅWavelength: 25 Å

Figure 3: Surface BAmplitude: 5 ÅWavelength: 37.5 Å

0.0 10.220.530.740.951.261.471.681.992.10

0.1

0.2

0.3

0.4

0.5

0.6

Distance from Surface (Å)

Den

sity

of P

olym

ers (

g/cc

)

ε = 0.0935

ε = 0.2805

ε = 0.187

Figure 9: Density profile for varying epsilons

Density of Short Polymers on Surface A with varying Interactive Energies

0.0 10.220.530.740.951.261.471.681.992.10

0.1

0.2

0.3

0.4

0.5

0.6

Distance from Surface (Å)

Den

sity

of P

olym

ers (

g/cc

)

ε = 0.0935

ε = 0.187

ε = 0.2805

Figure 10: Density profile for varying epsilons

Density of Short Polymers on Surface B with varying Interactive Energies