Banca de DEFESA: MARIANA ALVES LEITE DUTRA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : MARIANA ALVES LEITE DUTRA
DATA : 18/07/2016
HORA: 14:00
LOCAL: LAPET
TÍTULO:
A NEW ROUTE OF OBTAINING THE POLY(N-ISOPROPYLACRYLAMIDE-co-VINYL LAURATE AND THEIR CARACTERIZATION PHYSICAL-CHEMISTRY IN AQUEOUS MEDIUM
PALAVRAS-CHAVES:
POLY(N-ISOPROPYLACRYLAMIDE), POLY(N-ISOPROPYLACRILAMIDE-CO-VINYL LAURATE), N-ISOPROPILACRYLAMIDE, FT-IR, NMR, RHEOMETRY, SLS, DLS
PÁGINAS: 100
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Polímeros e Colóides
RESUMO:
The synthesis of copolymers containing N-isopropylacrylamide (NIPAAm) and hydrophobic comonomers, such as laurate vinyl (LV), has been done using organic solvents such as tetrahydrofuran (THF), and a water soluble initiator in this medium such as Azoisobutironitrila (AIBN). This study aimed to synthesis of two poly (N-isopropylacrylamide-co-vinyl laurate) with different molar percentage of monomers in the polymer chain and the evaluation of their properties. The polymerization was carried out by free radicals, replacing the organic solvent THF by water and AIBN initiator by potassium persulfate (K2S2O8). To LV contribution assessment in copolymers was also synthesized homopolymer NIPAAm under the same reaction conditions employed for the copolymers. The chemical structures of the polymers obtained were investigated by infrared spectroscopy (IR) and nuclear magnetic resonance of hydrogen (1H NMR) and carbon (13C NMR). Aqueous solutions of the polymers were analyzed by rheometry, static light scattering (SLS) and dynamic (DLS). The results of rheometry showed that consoluta temperature lower (lower critical solution temperature - LCST) of poly (N-isopropylacrylamide-co-laurate, vinyl) containing 7 mol% of LV was 26 ° C, while the copolymer containing 13 mol% LV was 21 ° C, in other words, lower than the LCST of PNIPAAm (34 ° C). This result indicates that the presence of hydrophobic monomer, LV, contributes significantly to reducing the LCST of the polymer. From the scattering of light static (SLS), calculated the weight apparent average molecular weight (w), the radius of gyration (Rg) and the second virial coefficient (A2) of the polymers. The w and A2 and poly (N-isopropylacrylamide-co-vinyl laurate) containing 7 mol% of LV was 3,0x106 g/mol and 16.1 mol.L.g-2, respectively, while that for the copolymer containing 13 mol% of VL, the values for w and A2 were 2,6x106 g/mol and - 4.27 mol.L.g-2, respectively. For PNIPAAm, the values of w and A2 were 3,2x107 g/mol and 0.69 mol.L.g-2, respectively. The decrease in the value of w of the copolymers relative to the w value of PNIPAAm was attributed to the reduction of the polymer-solvent interactions in the medium, which was confirmed by decreasing the value of A2 to the copolymers. The DLS analysis made concentration 1g/L in the temperature range 15 °C to 40 °C indicated the presence of isolated chains and aggregates of different sizes for the polymers.
MEMBROS DA BANCA:
Interno - 1803692 - FABRICIO GAVA MENEZES
Presidente - 1149440 - ROSANGELA DE CARVALHO BALABAN
Externo à Instituição - ROSSANA MARA DA SILVA MOREIRA THIRÉ - UFRJ