Banca de DEFESA: JOSÉ AURÉLIO PINHEIRO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSÉ AURÉLIO PINHEIRO
DATE: 04/02/2022
TIME: 13:00
LOCAL: Google meet
TITLE:

THERMORESPONSIVE CELLULOSE NANOCRYSTALS: EVALUATION OF THE VERSATILITY OF USE THROUGH TESTS IN DRILLING FLUIDS AND RAW MACROPHAGE CELLS.

KEY WORDS:

Poly(N-isopropylacrylamide), nanocellulose, thermoresponsive, drilling fluid, antioxidant.

PAGES: 100
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Polímeros e Colóides
SUMMARY:

In this study, cellulose nanocrystals (CNC) were obtained from acid hydrolysis of a commercial cotton cellulose sample. Then, the CNCs were chemically modified by grafting chains of the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM). Grafting reaction was performed using the monomer N-isopropylacrylamide (NIPAM) using the redox pair potassium persulfate/N,N,N',N'-tetramethylethylenediamine as initiators at room temperature (~ 25 °C), or by thermal activation (60 °C) of potassium persulfate. The materials were characterized by elemental analysis, Fourier Transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-Ray diffraction (XRD) and thermogravimetric analysis (TGA). The properties of CNC and their thermorresponsive derivatives in aqueous medium were evaluated by dynamic light scattering (DLS), zeta potential and confocal microscopy. In addition, the visual stability of modified materials in solvents of different polarities was evaluated. CNC grafted with PNIPAM were studied as additives in synthetic-based drilling fluids. They were able to reduce the filtrate under high temperature and high pressure (HTHP) conditions, indicating a high potential for application in the area. Furthermore, in a second line of applicability, in the biomedical area, modified CNC and its precursors were evaluated for cytotoxicity, immunomodulation and ability to reduce cellular oxidative stress. They exhibited good cytotoxic and antioxidant activities on RAW macrophage cells, even greater than their precursors. The protection of cells against oxidative damage by CNC-g-PNIPAM opens the way for application in the biomedical field.

BANKING MEMBERS:
Externa à Instituição - ANA MARIA DA SILVA MAIA - UFT
Externo ao Programa - 2195251 - HUGO ALEXANDRE DE OLIVEIRA ROCHA
Externo à Instituição - LISZT YELTSIN COUTINHO MADRUGA - UFRN
Interno - 072.972.174-41 - PAULO CÉSAR FRANÇA DA CÂMARA - null
Presidente - 1149440 - ROSANGELA DE CARVALHO BALABAN