Nanomechanical Characteristics of Photo-Cured Cyanoacrylate Bioadhesives Containing TMPTMA or POSS Nanostructures as Crosslinking Agents

Nanoindentation is an effective method to measure the mechanical properties of material surfaces in microscopic domains. Here, nanomechanical properties of photo-crosslinkable cyanoacrylate bioadhesives are reported using nonoindentation technique. Adhesives consisting of 2-octyl cyanoacrylate (2-OCA) and different percentages (0, 10, 20, 30 and 40 wt%) of POSS nanostructures or TMPTMA as crosslinking agents were prepared. PPD (1-phenyl-1,2-propanedione) was used (4 wt%) as photo-initiator. The specimens were photo-polymerized for 300 s using a light source with an irradiance of circa 500 mW.cm-2. The specimens were then irradiated for further 2 hrs in a light box to ensure the complete curing.The specimen surfaces were polished using abrasive papers (grit 2000) and attached to the sample holder of the instrument by applying a super glue adhesive. Nanomechanical properties of the specimens were measured using Nanoscope III (Hysitron Co., Germany) with a Berkovich indenter. The results (n=3 at least) were analyzed using Hysitron TriboScope software and compared using one-way ANOVA and Tukey test at the significance level of 0.05. The results showed that by incorporation of a crosslinking agent, surface modulus and hardness increased and force loss during holding (creep) decreased. Incorporation of the crosslinking agents into the cyanoacrylate increased elastic portion of viscoelastic properties. In addition, the sticky nature of the adhesive surface and its elastic nature resulted in interactions between the specimen surfaces and indenter, which in turn caused deviations from linear elasticity and Oliver and Pharr model. It is also concluded that the calibration model (Oliver and Pharr model) which is commonly used in the nonoindentation technique needs to be modified to consider the possible surface-indentor interactions.

کلیدواژه ها:

Nanoindentation ، Cyanoacrylate ، Bioadhesive ، POSS