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Molecular mechanics and performance of crosslinked amorphous polymer adhesives

Published online by Cambridge University Press:  13 May 2014

Max Solar ,
Zhao Qin  and
Markus J. Buehler
Max Solar
Affiliation:
Department of Civil and Environmental Engineering, Laboratory for Atomistic and Molecular Mechanics (LAMM), Massachusetts Institute of Technology, Cambridge, Massachusetts; and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
Zhao Qin
Affiliation:
Department of Civil and Environmental Engineering, Laboratory for Atomistic and Molecular Mechanics (LAMM), Massachusetts Institute of Technology, Cambridge, Massachusetts
Markus J. Buehler*
Affiliation:
Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; and Center for Computational Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; and Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
*
a)Address all correspondence to this author. e-mail: mbuehler@mit.edu
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Abstract

Amorphous polymers are among the most common materials used in adhesives, and a clear understanding of the effects of molecular scale features on macroscopic responses is necessary to design new, better performing adhesives. While many features have been investigated, including effects of molecular weight, inclusion of filler materials, and some effects of crosslinking, much of the understanding of the adhesive response remains empirical. Specifically, choosing the appropriate combination of polymer properties that optimize the work required to debond is still a challenge and the interplay between mechanical and chemical properties of polymers at interfaces is largely unknown. Here, we perform molecular dynamics simulations on a simple coarse-grained polymer model to directly investigate the role of crosslinking in determining the adhesive response of amorphous polymers at the molecular level. We find that crosslinking has a dramatic effect on the mechanical properties even at relatively low crosslink densities, and that crosslinking alone can be effective for optimizing the adhesive response of amorphous polymer adhesives. We observe a clear transition from cohesive to adhesive failure as the crosslink density is increased which coincides with the optimal toughening in the films. Furthermore, we find that our model captures the key molecular scale deformation mechanisms that control the adhesive response. For low crosslink densities, increased crosslinking improves the adhesive response by inhibiting chain sliding and allowing the structures to achieve large deformations, but as the crosslink density is increased further, the adhesive response is diminished due to reduced overall deformability. Our results provide simple but important insights into how crosslinking in amorphous polymer adhesives can be used to tune the mechanical response and ultimately to optimize adhesive performance for various applications.

Keywords

adhesionpolymercrosslinkmolecular mechanicsmultiscale model
Type
Articles
Information
Journal of Materials Research , Volume 29 , Issue 9 , 14 May 2014 , pp. 1077 - 1085
Copyright
Copyright © Materials Research Society 2014 

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References

REFERENCES

Pugno, N.M., Cranford, S.W., and Buehler, M.J.: Synergetic material and structure optimization yields robust spider web anchorages. Small 9(16), 2747 (2013).CrossRefGoogle ScholarPubMed
Cranford, S.W., Tarakanova, A., Pugno, N.M., and Buehler, M.J.: Nonlinear material behaviour of spider silk yields robust webs. Nature 482(7383), 72 (2012).CrossRefGoogle ScholarPubMed
Barlow, D.E., Dickinson, G.H., Orihuela, B., Kulp, J.L., Rittschof, D., and Wahl, K.J.: Characterization of the adhesive plaque of the barnacle Balanus amphitrite: Amyloid-like nanofibrils are a major component. Langmuir 26(9), 6549 (2010).CrossRefGoogle ScholarPubMed
Buehler, M.J., Yao, H.M., Gao, H.J., and Ji, B.H.: Cracking and adhesion at small scales: Atomistic and continuum studies of flaw tolerant nanostructures. Modell. Simul. Mater. Sci. Eng. 14(5), 799 (2006).CrossRefGoogle Scholar
Sahni, V., Blackledge, T.A., and Dhinojwala, A.: A review on spider silk adhesion. J. Adhes. 87(6), 595 (2011).CrossRefGoogle Scholar
Qin, Z. and Buehler, M.J.: Molecular mechanics of mussel adhesion proteins. J. Mech. Phys. Solids 62(1), 19 (2014).CrossRefGoogle Scholar
Knowles, T.P.J. and Buehler, M.J.: Nanomechanics of functional and pathological amyloid materials. Nat. Nanotechnol. 6(8), 469 (2011).CrossRefGoogle ScholarPubMed
Qin, Z. and Buehler, M.J.: Impact tolerance in mussel thread networks by heterogeneous material distribution. Nat. Commun. 4, 2187 (2013).CrossRefGoogle ScholarPubMed
Buehler, M.J.: Tu(r)ning weakness to strength. Nano Today 5(5), 379 (2010).CrossRefGoogle Scholar
Creton, C.: Pressure-sensitive adhesives: An introductory course. MRS Bull. 28(6), 434 (2003).CrossRefGoogle Scholar
Krenceski, M.A. and Johnson, J.F.: Shear, tack, and peel of polyisobutylene - Effect of molecular-weight and molecular-weight distribution. Polym. Eng. Sci. 29(1), 36 (1989).CrossRefGoogle Scholar
Khan, I. and Poh, B.T.: Natural rubber-based pressure-sensitive adhesives: A review. J. Polym. Environ. 19(3), 793 (2011).CrossRefGoogle Scholar
Gay, C. and Leibler, L.: On stickiness. Phys. Today 52(11), 48 (1999).CrossRefGoogle Scholar
Zosel, A.: Adhesive failure and deformation-behavior of polymers. J. Adhes. 30(1–4), 135 (1989).CrossRefGoogle Scholar
Dahlquist, C.A.: Pressure-sensitive adhesives. In Treatise on Adhesion and Adhesives; Patrick, R.L. ed.; Marcel Dekker: New York, 1969; p. 219.Google Scholar
Gent, A.N. and Schultz, J.: Effect of wetting liquids on strength of adhesion of viscoelastic materials. J. Adhes. 3(4), 281 (1972).CrossRefGoogle Scholar
Poh, B.T., Giam, Y.F., and Yeong, F.P.A.: Tack and shear strength of adhesives prepared from styrene-butadiene rubber (SBR) using gum rosin and petro resin as tackifiers. J. Adhes. 86(8), 844 (2010).CrossRefGoogle Scholar
Poh, B.T. and Yong, A.T.: Effect of molecular weight of epoxidized natural rubber on shear strength of adhesives. J. Appl. Polym. Sci. 114(6), 3976 (2009).CrossRefGoogle Scholar
Poh, B.T. and Yong, A.T.: Effect of molecular weight of rubber on tack and peel strength of SMR L-based pressure-sensitive adhesives using gum rosin and petroresin as tackifiers. J. Macromol. Sci. A 46(1), 97 (2009).CrossRefGoogle Scholar
Poh, B.T. and Yong, A.T.: Dependence of peel adhesion on molecular weight of epoxidized natural rubber. J. Adhes. 85(7), 435 (2009).CrossRefGoogle Scholar
Poh, B.T., Lee, P.G., and Chuah, S.C.: Adhesion property of epoxidized natural rubber (ENR)-based adhesives containing calcium carbonate. Express Polym. Lett. 2(6), 398 (2008).CrossRefGoogle Scholar
Lakrout, H., Creton, C., Ahn, D.C., and Shull, K.R.: Influence of molecular features on the tackiness of acrylic polymer melts. Macromolecules 34(21), 7448 (2001).CrossRefGoogle Scholar
Sherriff, M., Knibbs, R.W., and Langley, P.G.: Mechanism for action of tackifying resins in pressure-sensitive adhesives. J. Appl. Polym. Sci. 17(11), 3423 (1973).CrossRefGoogle Scholar
Tobing, S.D. and Klein, A.: Molecular parameters and their relation to the adhesive performance of emulsion acrylic pressure-sensitive adhesives. II. Effect of crosslinking. J. Appl. Polym. Sci. 79(14), 2558 (2001).3.0.CO;2-Y>CrossRefGoogle Scholar
Zosel, A.: Effect of cross-linking on tack and peel strength of polymers. J. Adhes. 34(1–4), 201 (1991).CrossRefGoogle Scholar
Auhl, R., Everaers, R., Grest, G.S., Kremer, K., and Plimpton, S.J.: Equilibration of long chain polymer melts in computer simulations. J. Chem. Phys. 119(24), 12718 (2003).CrossRefGoogle Scholar
Kremer, K. and Grest, G.S.: Dynamics of entangled linear polymer melts - A molecular-dynamics simulation. J. Chem. Phys. 92(8), 5057 (1990).CrossRefGoogle Scholar
Sides, S.W., Grest, G.S., Stevens, M.J., and Plimpton, S.J.: Effect of end-tethered polymers on surface adhesion of glassy polymers. J. Polym. Sci. Pol. Phys. 42(2), 199 (2004).CrossRefGoogle Scholar
Sides, S.W., Grest, G.S., and Stevens, M.J.K.: Large-scale simulation of adhesion dynamics for end-grafted polymers. Macromolecules 35(2), 566 (2002).CrossRefGoogle Scholar
Stevens, M.J.: Manipulating connectivity to control fracture in network polymer adhesives. Macromolecules 34(5), 1411 (2001).CrossRefGoogle Scholar
Stevens, M.J.: Interfacial fracture between highly cross-linked polymer networks and a solid surface: Effect of interfacial bond density. Macromolecules 34(8), 2710 (2001).CrossRefGoogle Scholar
Tsige, M., Lorenz, C.D., and Stevens, M.J.: Role of network connectivity on the mechanical properties of highly cross-linked polymers. Macromolecules 37(22), 8466 (2004).CrossRefGoogle Scholar
Tsige, M. and Stevens, M.J.: Effect of cross-linker functionality on the adhesion of highly cross-linked polymer networks: A molecular dynamics study of epoxies. Macromolecules 37(2), 630 (2004).CrossRefGoogle Scholar
Xia, W.J. and Keten, S.: Coupled effects of substrate adhesion and intermolecular forces on polymer thin film glass-transition behavior. Langmuir 29(41), 12730 (2013).CrossRefGoogle ScholarPubMed
Xia, W.J., Mishra, S., and Keten, S.: Substrate vs. free surface: Competing effects on the glass transition of polymer thin films. Polymer 54(21), 5942 (2013).CrossRefGoogle Scholar
Plimpton, S.: Fast parallel algorithms for short-range molecular-dynamics. J. Comput. Phys. 117(1), 1 (1995).CrossRefGoogle Scholar
Humphrey, W., Dalke, A., and Schulten, K.: VMD: Visual molecular dynamics. J. Mol. Graph. 14(1), 33 (1996).CrossRefGoogle ScholarPubMed
Marsagli, G.: Choosing a point from surface of a sphere. Ann. Math. Stat. 43(2), 645 (1972).CrossRefGoogle Scholar