| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 2.38 MB | Adobe PDF |
Authors
Abstract(s)
O polidimetilsiloxano (PDMS) tem atraído significativa atenção em diversas áreas devido às suas excelentes propriedades, mas sua hidrofobicidade inerente apresenta desafios em aplicações que exigem controle da molhabilidade. Este estudo fornece uma visão abrangente das principais estratégias para modificar a molhabilidade das superfícies de PDMS, focando nos métodos tradicionais e seu impacto no ângulo de contato e outras características relacionadas. Quatro técnicas principais foram estudadas, sendo elas o tratamento com plasma de oxigênio, a adição de surfactantes, o tratamento com UV-ozônio e a incorporação de nanomateriais, sendo a aplicada neste estudo a adição de surfactantes. Esses métodos são escolhidos entre os demais devido a sua ampla disponibilidade de literatura, menor complexidade e custo-benefício
em comparação com técnicas mais novas. O tratamento com plasma de oxigênio melhora a hidrofilicidade do PDMS ao introduzir grupos funcionais polares através da oxidação. A adição de surfactantes possui uma abordagem versátil para alterar a molhabilidade, sendo a escolha e a concentração dos surfactantes fundamentais para obter as propriedades desejadas da superfície. O tratamento com UV-ozônio aumenta com eficácia a energia da superfície por meio da indução de oxidação e geração de grupos funcionais hidrofílicos. A incorporação de nanomateriais nas matrizes de PDMS possibilita modificações promissoras na molhabilidade, permitindo propriedades de superfície que são ajustáveis através da dispersão controlada e interações interfaciais. Os efeitos das nanopartículas e dos nanotubos melhoram significativamente o com-
portamento de molhamento e a energia da superfície. Adicionalmente, esse estudo aborda os desafios da recuperação hidrofóbica no PDMS, especialmente considerável para dispositivos microfluídicos comerciais que se tem a exigência do armazenamento e distribuição prolongados. Um estudo comparando três surfactantes não iônicos (Triton X-100, Brij L4 (BL4) e Polietileno Óxido (PEO)) apresenta que a seleção de surfactantes deve considerar a eficiência, estabilidade e durabilidade do comportamento hidrofílico. Diversos tipos e concentrações de surfactantes e a suas temperaturas de cura foram testados, revelando que 2,5% de PEO curado a 80°C atingiu um ângulo de contato de 12,8° imediatamente após a cura. Análises de condutividade térmica indicaram que 0,5% de TX-100 a 80°C era ideal inicialmente, enquanto 2,5% de
BL4 a 25°C apresentou melhor desempenho após três semanas. Análises estatísticas, incluindo o método Taguchi e a Análise Relacional de Grey, validam ainda mais a influência de vários parâmetros na molhabilidade e condutividade térmica.
Polydimethylsiloxane (PDMS) has attracted significant attention in several areas due to its excellent properties, but its inherent hydrophobicity presents challenges in applications that require control of wettability. This study provides a comprehensive overview of the main strategies for modifying the wettability of PDMS surfaces, focusing on traditional methods and their impact on the contact angle and other related characteristics. Four main techniques are discussed: oxygen plasma treatment, addition of surfactants, UV-ozone treatment and incorporation of nanomaterials. These methods are chosen over the others due to their wide availability in the literature, lower complexity and cost-effectiveness compared to newer techniques. Oxygen plasma treatment improves the hydrophilicity of PDMS by introducing polar functional groups through oxidation. The addition of surfactants has a versatile approach to change wettability, with the choice and concentration of surfactants being the key to obtain the desired surface properties. UV-ozone treatment effectively increases surface energy by inducing oxidation and generating hydrophilic functional groups. The incorporation of nanomaterials into PDMS matrices enables promising modifications in wettability, allowing for surface properties that are adjustable through controlled dispersion and interfacial interactions. The effects of nanoparticles and nanotubes significantly improve wetting behavior and surface energy. Additionally, this study addresses the challenges of hydrophobic recovery in PDMS, especially considerable for commercial microfluidic devices that require prolonged storage and distribution. A study comparing three non-ionic surfactants (Triton X-100, Brij L4 (BL4) and Polyethylene Oxide (PEO)) shows that the selection of surfactants must consider the efficiency, stability and durability of the hydrophilic behavior. Various types and concentrations of surfactants and their curing temperatures were tested, revealing that 2.5% PEO cured at 80°C reached a contact angle of 12.8° immediately after curing. Thermal conductivity analyses indicated that 0.5% TX-100 at 80°C was ideal right after the cure, while 2.5% BL4 at 25°C performed better after three weeks. Statistical analyses, including the Taguchi method and Grey's Relational Analysis, further validate the influence of various parameters on wettability and thermal conductivity.
Polydimethylsiloxane (PDMS) has attracted significant attention in several areas due to its excellent properties, but its inherent hydrophobicity presents challenges in applications that require control of wettability. This study provides a comprehensive overview of the main strategies for modifying the wettability of PDMS surfaces, focusing on traditional methods and their impact on the contact angle and other related characteristics. Four main techniques are discussed: oxygen plasma treatment, addition of surfactants, UV-ozone treatment and incorporation of nanomaterials. These methods are chosen over the others due to their wide availability in the literature, lower complexity and cost-effectiveness compared to newer techniques. Oxygen plasma treatment improves the hydrophilicity of PDMS by introducing polar functional groups through oxidation. The addition of surfactants has a versatile approach to change wettability, with the choice and concentration of surfactants being the key to obtain the desired surface properties. UV-ozone treatment effectively increases surface energy by inducing oxidation and generating hydrophilic functional groups. The incorporation of nanomaterials into PDMS matrices enables promising modifications in wettability, allowing for surface properties that are adjustable through controlled dispersion and interfacial interactions. The effects of nanoparticles and nanotubes significantly improve wetting behavior and surface energy. Additionally, this study addresses the challenges of hydrophobic recovery in PDMS, especially considerable for commercial microfluidic devices that require prolonged storage and distribution. A study comparing three non-ionic surfactants (Triton X-100, Brij L4 (BL4) and Polyethylene Oxide (PEO)) shows that the selection of surfactants must consider the efficiency, stability and durability of the hydrophilic behavior. Various types and concentrations of surfactants and their curing temperatures were tested, revealing that 2.5% PEO cured at 80°C reached a contact angle of 12.8° immediately after curing. Thermal conductivity analyses indicated that 0.5% TX-100 at 80°C was ideal right after the cure, while 2.5% BL4 at 25°C performed better after three weeks. Statistical analyses, including the Taguchi method and Grey's Relational Analysis, further validate the influence of various parameters on wettability and thermal conductivity.
Description
Mestrado de dupla diplomação com o Instituto Federal do Rio Grande do Sul
Keywords
Modificação de superfícies Hidrofilicidade Microfluídica