Novel michael addition networks containing urethane hydrogen bonding

Bio-Based Polymer Developments from Tall Oil Fatty Acids by Exploiting Michael Addition

In this study, previously developed acetoacetates of two tall-oil-based and two commercial polyols were used to obtain polymers by the Michael reaction. The development of polymer formulations with varying cross-link density was enabled by different bio-based monomers in combination with different acrylates—bisphenol A ethoxylate diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate. New polymer materials are based on the same polyols that are suitable for polyurethanes. The new polymers have qualities comparable to polyurethanes and are obtained without the drawbacks that come with polyurethane extractions, such as the use of hazardous isocyanates or reactions under harsh conditions in the case of non-isocyanate polyurethanes. Dynamic mechanical analysis, differential scanning calorimetry, thermal gravimetric analysis, and universal strength testing equipment were used to investigate the physical and thermal characteristics of the created polymers. Polymers with a wide range of thermal and mechanical properties were obtained (glass transition temperature from 21 to 63 °C; tensile modulus (Young’s) from 8 MPa to 2710 MPa and tensile strength from 4 to 52 MPa). The synthesized polymers are thermally stable up to 300 °C. The suggested method may be used to make two-component polymer foams, coatings, resins, and composite matrices.

Michael Addition Reaction Kinetics of Acetoacetates and Acrylates for the Formation of Polymeric Networks

2-Ethylhexyl acrylate and ethyl acetoacetate were reacted in a Carbon – Michael addition reaction as a model for subsequent studies of polymer networks. A statistical design of reactions was conducted in the presence of an in-situ ATR FTIR spectrometer to determine the effect of solvent, base, base concentration, and reactant stoichiometry on the observed rate constant. In particular, a central composite statistical design of experiments analysis was performed for model reactions that were catalyzed using either 1,8-diazbicyclo[5.4.0]undec-7-ene (DBU) or K2CO3 at various concentrations. Poly(propylene glycol) bisacetoacetate (PPG BisAcAc) and poly(propylene glycol) diacrylate (PPGDA) networks were then prepared in the absence of solvent at 23°C based on optimized conditions in the presence of DBU and K2CO3. In a similar fashion to model studies, in-situ FTIR spectroscopy was utilized, and observed rate constants were determined. The influence of PPG BisAcAc molecular weight on dynamic mechanical properties was determined and gel fraction analysis was conducted. It appears that the selection of base significantly altered the rate of the reaction, but had an insignificant effect on mechanical properties.