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Roles of chemical and physical crosslinking on the rheological properties of silica-doped polyacrylamide hydrogels

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This paper examines the nanoparticle (NP) influence on energy storage and dissipation in hydrogel nanocomposites (HNCs). To obtain fundamental insights into mechanical enhancement, a model system involving the in situ free-radical polymerization of acrylamide with bis-acrylamide (bis) and silica NPs is adopted. The loss tangents of the unmodified polymer networks span three orders of magnitude, and the weak attraction between silica and poly(acrylamide) (PA)—as compared to composites with a stronger NP-polymer interaction—makes these HNCs particularly sensitive to systematic variations in (i) NP size and concentration and (ii) monomer and crosslinker concentrations. From the dynamic shear moduli during polymerization, and their spectra at steady-state, silica NPs in PA behave as multi-functional, physical crosslinking centers that increase the storage modulus, particularly in very weakly bis-crosslinked PA (in which NP aggregates are proposed to form elastically effective clusters). The loss modulus for HNCs reflects adsorption/desorption and friction at the NP surfaces, varying with the NP, monomer and crosslinker concentrations. Silica NPs were also found to slow the polymerization and crosslinking of acrylamide according to the specific NP surface area (set by the NP size and concentration), suggesting that silica NPs reduce the free-radical concentration.

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  1. “Brittle” is used in this context to describe breaking by fracture, which occurs in hydrogels without accumulating plastic deformation.

  2. The surface chemistry of the modified silica surface was not reported.

  3. This term is used to describe inclusions that do not modify the structure of the continuous (PA hydrogel) phase.


  • Adibnia V, Hill RJ (2014) Electroacoustic spectroscopy of nanoparticle-doped hydrogels. Macromolecules 47:8064–8071

    Article  Google Scholar 

  • Adibnia V, Hill RJ (2016) Universal aspects of hydrogel gelation kinetics, percolation and viscoelasticity from PA-hydrogel rheology. J Rheol 60:541–548

    Article  Google Scholar 

  • Akcora P, Kumar SK, Moll J, Lewis S, Schadler LS, Li Y, Benicewicz BC, Sandy A, Narayanan S, Ilavsky J, Thiyagarajan P, Colby H (2010) Gel-like mechanical reinforcement in polymer nanocomposite melts. Macromolecules 43:1003–1010

    Article  Google Scholar 

  • Aranguren MI, Mora E, DeGroot JV, Macosko CW (1992) Effect of reinforcing fillers on the rheology of polymer melts. J Rheol 36:1165–1182

    Article  Google Scholar 

  • Balazs AC, Emrick T, Russell TP (2006) Nanoparticle polymer composites: where two small worlds meet. Science:314

  • Bhosale PS, Chun J, Berg JC (2011) Electroacoustics of particles dispersed in polymer gel. Langmuir 27:7376–7379

    Article  Google Scholar 

  • Brooks DE (1973) The effect of neutral polymers on the electrokinetic potential of cells and other charged particles: II. a model for the effect of adsorbed polymer on the diffuse double layer. J Colloid Interface Sci 43:687–699

  • Calvet D, Wong JY, Giasson S (2004) Rheological monitoring of polyacrylamide gelation: importance of cross-link density and temperature Macromolecules

  • Caregnato P, Le Roux GC, Martire DO, Gonzalez MC (2005) Kinetic studies on the sulfate radical-initiated polymerization of vinyl acetate and 4-vinyl pyridine in the presence of silica nanoparticles. Langmuir 21:8001–8009

    Article  Google Scholar 

  • Catsimpoolas N (1976) editor. Method of Protein Separation, vol 2. Springer

  • Censi R, Di Martino P, Vermonden T, Hennink WE (2012) Hydrogels for protein delivery in tissue engineering. J Control Release 161:680–692

    Article  Google Scholar 

  • Deligkaris K, Tadele TS, Olthuis W, Berg A (2010) Hydrogel-based devices for biomedical applications Sensor Actuat. B-Chem 147:765–774

    Google Scholar 

  • Di Michele L, Yanagishima T, Brewer AR, Kotar J, E. E (2011) Interactions between colloids induced by a soft cross-linked polymer substrate. Phys Rev Lett 107:136101

  • Gaharwar AK, Rivera CP, Wu CJ, Schmidt G (2011) Transparent, elastomeric and tough hydrogels from poly(ethylene glycol) and silicate nanoparticles. Acta Biomater 7:4139–4148

    Article  Google Scholar 

  • Gaharwar AK, Rivera C, Wu CJ, Chan BK, G. S (2013) Photocrosslinked nanocomposite hydrogels from peg and silica nanospheres Structural, mechanical and cell adhesion characteristics. Mat Sci Eng C 33:1800–1807

    Article  Google Scholar 

  • Giraldo J, Vivas NM, Vila E, Badia A (2002) Assessing the (a)symmetry of concentration-effect curves: empirical versus mechanistic models. Pharmacol Ther 95:21–45

    Article  Google Scholar 

  • Guth E (1945) Theory of filler reinforcement. J Appl Phys 16:20–25

    Article  Google Scholar 

  • Haraguchi H, Takehisa T, Fan S (2002) Effects of clay content on the properties of nanocomposite hydrogels composed of poly(n-isopropylacrylamide) and clay. Macromolecules 35:10162– 10171

    Article  Google Scholar 

  • Haraguchi K (2007) Nanocomposite hydrogels. Curr Opin Solid St M 11:47–54

    Article  Google Scholar 

  • Haraguchi K, Song L (2007) Microstructures formed in co-cross-linked networks and their relationships to the optical and mechanical properties of pnipa/clay nanocomposite gels. Macromolecules 40:5526–5536

    Article  Google Scholar 

  • Haraguchi K, Farnworth R, Ohbayashi A, Takehisa T (2003) Compositional effects on mechanical properties of nanocomposite hydrogels composed of poly(n,n-dimethylacrylamide) and clay. Macromolecules 36:5732–5741

    Article  Google Scholar 

  • Haraguchi K, Li HJ, Matsuda K, Takehisa T, Elliott E (2005) Mechanism of forming organic/inorganic network structures during in-situ free-radical polymerization in PNIPA-clay nanocomposite hydrogels. Macromolecules 38:3482–3490

    Article  Google Scholar 

  • Hill AV (1913) The combinations of haemoglobin with oxygen and with carbon monoxide. Biochem J 7:471–480

    Article  Google Scholar 

  • Larson RJ (1999) The structure and rheology of complex fluids Oxford University Press

  • Lin WC, Fan W, Marcellan A, Hourdet D, Creton C (2010) Large strain and fracture properties of poly(dimethylacrylamide)/silica hybrid hydrogels. Macromolecules 43:2554–2563

    Article  Google Scholar 

  • Lin WC, Marcellan A, Hourdet D, C. C (2011) Effect of polymer–article interaction on the fracture toughness of silica filled hydrogels. Soft Matter 7:6578–6582

    Article  Google Scholar 

  • Lusti HR, Karmilov IA, Gusev AA (2002) Effect of particle agglomeration on the elastic properties of filled polymers. Soft Matter 1:115–120

    Article  Google Scholar 

  • Mahaut F, Chateau X, Coussot P, Ovarlez G (2008) Yield stress and elastic modulus of suspensions of noncolloidal particles in yield stress fluids. J Rheol 52:287–313

    Article  Google Scholar 

  • Okay O, Oppermann W (2007) Polyacrylamide-clay nanocomposite hydrogels: rheological and light scattering characterization. Macromolecules 40:3378–3387

    Article  Google Scholar 

  • Peppas NA, Hilt JZ, Khademhosseini A, Langer R (2006) Hydrogels in biology and medicine: from molecular principles to bionanotechnology. Adv Mater 18:1345–1360

    Article  Google Scholar 

  • Petit L, Bouteiller L, Brulet A, Lafuma F, Hourdet D (2007) Responsive hybrid self-assemblies in aqueous media. Langmuir 23:147–158

    Article  Google Scholar 

  • Ratner BD, Bryant SJ (2004) Biomaterials Where we have been and where we are going. Annu Rev Biomed Eng 6:41–75

    Article  Google Scholar 

  • Rose S, Marcellan A, Hourdet D, Creton C, Narita T (2013) Dynamics of hybrid polyacrylamide hydrogels containing silica nanoparticles studied by dynamic light scattering. Macromolecules 46:4567–4574

    Article  Google Scholar 

  • Samoshina Y, Diaz A, Becker Y, Nylander T, Lindmana B (2003) Adsorption of cationic, anionic and hydrophobically modified polyacrylamides on silica surfaces. Colloids Surf A 231:195–205

    Article  Google Scholar 

  • Schexnailder P, Schmidt G (2009) Nanocomposite polymer hydrogels. Colloid Polym Sci 287:1–11

    Article  Google Scholar 

  • Ye L, Tang Y, Qiu D (2014) Enhance the mechanical performance of polyacrylamide hydrogel by aluminium-modified colloidal silica. Colloids Surf A 447:103–110

    Article  Google Scholar 

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Financial support from the NSERC Discovery and NSERC Research Tools and Instruments programs is gratefully acknowledged. V.A. supported, in part, by a McGill Engineering Doctoral Award (MEDA). S.M.T. supported by NSERC Banting and McGill Tomlinson post-doctoral scholarships.

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Correspondence to Reghan J. Hill.

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Adibnia, V., Taghavi, S.M. & Hill, R.J. Roles of chemical and physical crosslinking on the rheological properties of silica-doped polyacrylamide hydrogels. Rheol Acta 56, 123–134 (2017).

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