Photo-polymerization, swelling and mechanical properties of cellulose fibre reinforced poly(ethylene glycol) hydrogels

Abstract

a b s t r a c tThe application of hydrogels as load-bearing biomedical components is often limited by their mechanical properties. Often an attempt to improve a hydrogel's stiffness is accompanied by a loss of toughness and swelling properties. In this work, we show that the addition of nanofibrillated cellulose (NFC) provides a mean to tailor both the swelling and the mechanical properties of the hydrogel. Various volume fractions of NFC were added to poly(ethylene glycol) dimethacrylate (PEGDM) precursors with two different molecular weights (6 and 20 kDa). The viscosity measurements of the precursor solutions indicated that the dispersed NFCs form a network-like structure in the hydrogel precursor. Such a structure, as observed in the photo-rheology experiments, serves as a light-scattering source when the solution is illuminated by UV light, which provides a uniform polymerization of the hydrogel in three-dimension and reduces the curing time. Mechanical properties of the neat and composite hydrogels were characterized using monotonic and cyclic compression tests. NFC reinforcement increases the hydrogel's stiffness by a factor 2 and 3.5 for the PEGDM matrixes with molecular weights of 6 and 20 kDa respectively without compromising their toughness. Moreover, the desired stiffness and swelling properties can be simultaneously achieved by adapting the reinforcement concentration and the hydrogel cross-link density. The obtained composite hydrogels offer enhanced and tuneable properties and are proposed for injectable and photo-curable load-bearing implants.

Tailoring swelling to control softening mechanisms during cyclic loading of PEG/cellulose hydrogel composites

“…Hydrogel precursors were prepared according to an established protocol [13]. PEGDM, phosphate buffered saline (PBS, pH 7.4, Gibco), NFC and 0.1 g ml −1 % of Irgacure 2959 (BASF), were mixed as photoinitiator using ultra-turrax (IKA T25 digital, SN 25 10G).…”

“…The rheology results on PEGDM-NFC composite hydrogel precursor [13] showed that composite hydrogel is composed of two networks; a covalently bonded PEGDM network as well as the network of NFC fibers formed through physical entanglements and hydrogen bonds (see Fig. 5).…”

“…Designing composite hydrogel is one of the approaches proposed to improve their mechanical properties [9][10][11][12] The hydrogel properties can be tailored by changing the reinforcement concentration while preserving in situ applicability of the hydrogel implants [13]. Furthermore, hybrid and hierarchical microstructure of various natural tissues such as cartilage or the core of intervertebral disc (i.e.…”

Miniature probe for the delivery and monitoring of a photopolymerizable material

“…Conversions of 30% or 50% might already be sufficient to achieve a sufficiently cured material. 28 As poly(ethylene glycol) (PEG)-base gels usually swell when immersed into water of PBS, 29 the increase in volume could also be attributed to swelling and not photopolymerization. Yet, the impact of dissolved PEG molecules on the ionic strength of the solvent is much higher than the impact of dissolved ions in the PBS (Na þ , Cl − , K þ , PO 3− 4 , etc.).…”

In vitro Implementation of Photopolymerizable Hydrogels as a Potential Treatment of Intracranial Aneurysms

“…The polymerization was considered complete when G reached a plateau level. The time required to reach 95% of the plateau level of G was defined as polymerization time, noted t 95 , as previously reported (Khoushabi et al, 2015).…”