Multi-scale mechanical and transport properties of a hydrogel.

In this paper, molecular dynamic simulation was used to study the effect of water on the equilibrated structure and mechanical properties of cross-linked hydrogel at multiple scales. The hydrogel consisted of Polyethylene glycol diglycidyl ether (PEGDGE) as epoxy and the Jeffamine, poly-oxy-alkylene-amines, as curing agent. The results for systems with various water contents indicated that the cross-links were more hydrophilic within the hydrogel structure. Effects of cross-linking on the transport properties were also investigated by computing diffusion coefficients of water molecules. A new Coarse-Grained (CG) scheme for hydrogels is proposed, and validated by comparing the transport properties with the all-atom method, demonstrating the capability of the model to capture the correct dynamic evolution of the system. The all-atom model of the hydrogel was mapped to the CG model using the MARTINI force field. This method resulted in a more realistic representation of the stiffness of the system, compared to the previous experimental studies in the literature. The variation of the stiffness of the hydrogel as a function of the water content showed that 40% water content is the optimal value for mechanical performance of the hydrogel.

[1]  David J. Pine,et al.  Rapidly recovering hydrogel scaffolds from self-assembling diblock copolypeptide amphiphiles , 2002, Nature.

[2]  M. Dadsetan,et al.  Effect of hydrogel porosity on marrow stromal cell phenotypic expression. , 2008, Biomaterials.

[3]  M. Grujicic,et al.  The effect of covalent functionalization of carbon nanotube reinforcements on the atomic-level mechanical properties of poly-vinyl-ester-epoxy , 2007 .

[4]  Pengyu Y. Ren,et al.  The COMPASS force field: parameterization and validation for phosphazenes , 1998 .

[5]  U. Suter,et al.  Detailed molecular structure of a vinyl polymer glass , 1985 .

[6]  W. Goddard,et al.  Mechanical and transport properties of the poly(ethylene oxide)-poly(acrylic acid) double network hydrogel from molecular dynamic simulations. , 2007, The journal of physical chemistry. B.

[7]  S. Jang,et al.  Molecular dynamics simulation study of P (VP-co-HEMA) hydrogels: effect of water content on equilibrium structures and mechanical properties. , 2009, Biomaterials.

[8]  N. Rahbar,et al.  Nano-scale fracture toughness and behavior of graphene/epoxy interface , 2012 .

[9]  Alberto Fernandez-Nieves,et al.  Highly responsive hydrogel scaffolds formed by three-dimensional organization of microgel nanoparticles. , 2008, Nano letters.

[10]  Erik Pierstorff,et al.  Active nanodiamond hydrogels for chemotherapeutic delivery. , 2007, Nano letters.

[11]  Weijian Xu,et al.  Atomistic molecular modelling of crosslinked epoxy resin , 2006 .

[12]  O. Wichterle,et al.  Hydrophilic Gels for Biological Use , 1960, Nature.

[13]  Hideki Tanaka,et al.  Molecular Dynamics Study of Polymer−Water Interaction in Hydrogels. 1. Hydrogen-Bond Structure , 1996 .

[14]  Maurizio Fermeglia,et al.  Polymer-clay nanocomposites: a multiscale molecular modeling approach. , 2007, The journal of physical chemistry. B.

[15]  Mark S.P. Sansom,et al.  Carbon nanotube/detergent interactions via coarse-grained molecular dynamics. , 2007, Nano letters.

[16]  W. Goddard,et al.  Charge equilibration for molecular dynamics simulations , 1991 .

[17]  Animesh Agrawal,et al.  Strong fiber-reinforced hydrogel. , 2013, Acta biomaterialia.

[18]  S. Marrink,et al.  The MARTINI force field , 2008 .

[19]  P. Calvert.  Hydrogels for Soft Machines , 2009 .

[20]  D. Tieleman,et al.  The MARTINI force field: coarse grained model for biomolecular simulations. , 2007, The journal of physical chemistry. B.

[21]  A. Mark,et al.  Coarse grained model for semiquantitative lipid simulations , 2004 .

[22]  Jean-Marie Lehn,et al.  Gelation-driven component selection in the generation of constitutional dynamic hydrogels based on guanine-quartet formation , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[23]  Robert E. Rudd,et al.  COARSE-GRAINED MOLECULAR DYNAMICS AND THE ATOMIC LIMIT OF FINITE ELEMENTS , 1998 .

[24]  Sony Joseph,et al.  Effect of cross-linking on the diffusion of water, ions, and small molecules in hydrogels. , 2009, The journal of physical chemistry. B.

[25]  H. Sun,et al.  COMPASS: An ab Initio Force-Field Optimized for Condensed-Phase ApplicationsOverview with Details on Alkane and Benzene Compounds , 1998 .

[26]  Valentina Tozzini,et al.  Coarse-grained models for proteins. , 2005, Current opinion in structural biology.

[27]  Laurent David,et al.  Multi-membrane hydrogels , 2008, Nature.

[28]  Mark W Grinstaff,et al.  Biodendrimer-based hydrogel scaffolds for cartilage tissue repair. , 2006, Biomacromolecules.

[29]  George C Schatz,et al.  Modeling the self-assembly of peptide amphiphiles into fibers using coarse-grained molecular dynamics. , 2012, Nano letters.

[30]  Sharon C. Glotzer,et al.  Simulated Assembly of Nanostructured Organic/Inorganic Networks , 2003 .

[31]  N. Rahbar,et al.  Nanoscale Structure and Mechanical Properties of Cross-Linked Hydrogels , 2015 .

[32]  A. Khademhosseini,et al.  Hydrogels in Biology and Medicine: From Molecular Principles to Bionanotechnology , 2006 .

[33]  M. Dadsetan,et al.  Characterization of photo-cross-linked oligo[poly(ethylene glycol) fumarate] hydrogels for cartilage tissue engineering. , 2007, Biomacromolecules.

[34]  N. Peppas,et al.  Physicochemical foundations and structural design of hydrogels in medicine and biology. , 2000, Annual review of biomedical engineering.