The interaction and adsorption of enzyme, glucose oxidase (GOx), on poly(methyl methacrylate)-bovine serum albumin (PMMA-BSA) particles were studied by using a quartz crystal microbalance with dissipation (QCM-D) and laser light scattering (LLS). The enzyme was irreversibly immobilized on the PMMA-BSA particle surface. The amount of enzyme immobilized on PMMA-BSA particles and the enzymatic activity were determined by UV/vis measurements. The influences of pH and ionic strength on the adsorption indicate that the electrostatic interaction plays a major role on the immobilization. The adsorbed GOx can retain at least 80% of the free enzyme activity. Thermal stability studies reveal that the adsorbed GOx only losses 28% of its activity in comparison with a 64% activity loss of free GOx when it is incubated at 50 degrees C for 35 h.
A series
of amide-functionalized ionic liquids (ILs), e.g., 1-R-3-(2-amino-2-oxoethyl)-imidazolium
(R = −vinyl, −methyl–butyl) cations combined
with Cl–, N(CN)2–, or NTf2
– anions, were synthesized and fully characterized
as curing agent for diglycidyl-4,5-epoxy-cyclohexane-1,2-dicarboxylate
(TDE-85). Studies of curing behaviors showed that ILs with N(CN)2
– anions exhibit moderate curing conditions.
As to thermosets of TDE-85 cured by these curing agents, their tensile
strength (95.1–111.7 MPa) and elongation at break (2.69 to
4.20%) are significantly improved compared with the traditional curing
systems of DDS/TDE-85 (DDS, 4,4′-diamino diphenyl sulphone).
These thermosets also exhibit good thermal mechanical properties with
the glass transition temperature (T
g)
> 200 °C and thermal degradation temperature (T
d) > 300 °C. The possible mechanisms of curing
reactions
were analyzed by using IR, and results indicated that curing reactions
of TDE-85 with amide-functionalized ionic liquids may include three
steps, −NH2 groups reacted with oxirane at lower
temperatures, and then the anions further participated in the reaction
to strengthen the cross-linking networks. This study provides informative
guidelines for designing new curing agents.
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