Síntese e caracterização de oligômeros termossensíveis com grupos terminais reativos via polimerizaçãoradicalar controlada

Abstract

N-isopropylacrylamide oligomers with a single reactive functional carboxyl end-group in their chain were synthesized at 70°C/5h, by using DMF as a solvent, by controlled radical polymerization technique. The 2,2-azobisisobutyronitrile was used as chemical initiator and the acid 3-mercaptopropionic as chain transfer and functionalization agent of the oligomer as well. The reagents concentrations were kept constant, with the exception of the chain transfer agent. Afterwards, five values for the ratio between the molar concentration of the acid 3-mercaptopropionic and the monomer were defined: 0,025 0,05 0,0625 0,075 0,1. The polymer was characterized by its molar mass, degree of polymerization, reaction yield and kinetic study of the homopolymerization and, with the purpose of verifying the presence of the functionality onto molecular oligomer, infrared spectrometer analyses were done. From the statistical analysis of the data by simple linear regression, it was observed that the values of the numerical average molar mass and the degree of polymerization had decreased linearly with the increase of the MPA/NIPAAm molar ratio. Concerning the percentage of reactional yield, it was possible to conclude that the obtained results were weakly influenced by the explanatory variable. Concerning the kinetic study of the reaction, there was no observed correlation. In the spectra obtained by FTIR analysis the characteristic bands of the oligomer formed were identified, highlighting the success of the polymerization process.