Banca de QUALIFICAÇÃO: DIEGO MOREIRA LIMA
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.STUDENT : DIEGO MOREIRA LIMA
DATE: 05/03/2024
TIME: 10:00
LOCAL: por participação remota
TITLE:
4D printing of thermoresponsive nanocomposite hydrogels based on Poly(N-isopropylacrylamide), cellulose nanocrystals, and Boron Nitride Nanosheets.
PAGES: 50
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Polímeros, Aplicações
SUMMARY:
4D Printing is an additive manufacturing technique capable of developing structures with properties that change in response to external stimuli. In this context, the application of Poly(N-isopropylacrylamide) (PNIPAm) hydrogel appears promising due to its ability to undergo structural changes in response to temperature variations. However, the hydrogel exhibits limitations in terms of stability and shape fidelity post-printing, requiring the inclusion of rheological modifiers to optimize material processability. Among the potential modification routes, cellulose nanocrystals (CNC) were chosen, known for their high mechanical strength. During the printing process of precursor gels, it is expected that CNC will be oriented through extrusion, enabling the creation of anisotropic materials with shape-changing capabilities (4D) in response to thermal fluctuations. Nevertheless, the resulting nanocomposites show reduced mechanical properties, fragmenting during mold removal and/or transportation to other platforms. To mitigate material fragility, alginate cross-linking is performed with bivalent cations [Ca2+], a process that inhibits shape change. To reduce the double cross-linking concentration, the use of functionalized boron nitride nanosheets (f-BNNS) is proposed. These nanoparticles exhibit high thermal conductivity and functional groups capable of interacting with polymers via hydrogen bonds. Their incorporation is expected to enhance the mechanical strength and thermoresponsiveness of PNIPAm hydrogel without compromising its shape-changing properties. Thus, four formulations with concentrations of 0%, 0.05%, 0.1%, and 0.2% (w/w relative to PNIPAm) of f-BNNS were analyzed. The behavior of the 4D response and shape fidelity is investigated, aiming to establish correlations with CNC alignment through optical microscopy (OM) and atomic force microscopy (AFM).
COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1761120 - DANILO JUSTINO CARASTAN
Membro Titular - Examinador(a) Interno ao Programa - 052.991.506-52 - JULIANA DA SILVA BERNARDES - UFABC
Membro Titular - Examinador(a) Externo à Instituição - MARCOS AKIRA D'ÁVILA - UNICAMP
Membro Suplente - Examinador(a) Interno ao Programa - 035.297.869-42 - RUBIA FIGUEREDO GOUVEIA - UFABC
Membro Suplente - Examinador(a) Externo ao Programa - 1604317 - SONIA MARIA MALMONGE
Membro Suplente - Examinador(a) Externo ao Programa - 1762438 - JEAN JACQUES BONVENT