Diagnósticos de plasmas de dietilenoglicol dimetil-eter (DIGLIME), 2-metil-2-oxazolina (OXAZOLINA) e da mistura de etilenodiamina com acetileno (EDA e C2H2): deposição polimérica
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Data
2019-07-26
Autores
Moreira Júnior, Pedro William Paiva [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho foram produzidos filmes finos de polímeros a partir da técnica de polimerização a plasma dos monômeros dietilenoglicol dimetil-eter (diglime), 2-metil-2-oxazolina (oxazolina) e da mistura de etilenodiamina (EDA) e o gás acetileno (C2H2), obtidos em baixa pressão. Esses materiais podem possuir um conjunto de características que são necessárias para aplicações na área da biomedicina. Os plasmas foram analisados por meio das técnicas de sonda de Langmuir (LP) e de espectroscopia ótica de emissão (OES). A caracterização dos polímeros foi realizada por meio das técnicas de medidas de ângulo de contato e energia de superfície (AC e ES), microscopia de força atômica (AFM), microscopia confocal (MC) e espectroscopia infravermelha por transformada de Fourier (FTIR). As características dos plasmas foram correlacionadas às propriedades dos polímeros a fim de se obter informações sobre os processos de polimerização, objetivando que o processo de produção de materiais com características desejáveis seja feito de forma controlada. Foram observadas temperaturas eletrônicas de elétrons frios entre 0,2 e 1,6 eV, e as densidades de plasmas foram da ordem de 10^15 m^-3. O comportamento da temperatura eletrônica em função da pressão de operação e da potência aplicada aos plasmas foi relacionado à produção de espécies CH, CO e Hα em plasmas de diglime, CH, CN, CO e NH em plasmas de 2-metil-2-oxazolina e CH, CN e NH em plasmas da mistura de EDA e C2H2. A participação dessas espécies nos processos de polimerização foi investigada por meio de observações das rugosidades médias das superfícies dos filmes finos, das ligações químicas observadas por FTIR e da taxa de deposição, revelando que as espécies CO, nos plasmas de diglime, e CN, nos plasmas da mistura de EDA e C2H2, eram responsáveis pela produção de grupos voláteis tanto na superfície dos filmes quanto em suspensão, diminuindo então suas participações nos processos de deposição. Não foram observadas características que revelassem os mesmos comportamentos no processo de polimerização do monômero 2-metil-2-oxazolina. Ao invés disso, elevadas taxas de deposição, decréscimos relativos de anéis fechados de oxazolina na estrutura dos polímeros e pelo menos três tipos de ligação contendo átomos de oxigênio foram observados, revelando que o processo a plasma foi capaz de promover, de forma efetiva, a abertura dos anéis das moléculas do monômero, e consecutivas fragmentações. Todos os polímeros apresentaram caráter hidrofílico, relacionado tanto a presença de grupos polares nos filmes, quanto ao nível de entrelaçamento das cadeias. Para os polímeros produzidos a plasmas de 2-metil-2-oxazolina, observou-se uma alta concentração de grupos polares que foram responsáveis por ângulos de contato próximos de 10 graus e a concentração de grupos nitrogenados (aminas) em polímeros produzidos a plasmas da mistura de EDA e C2H2, estiveram intimamente relacionados ao comportamento do ângulo de contato. Polímeros mais ricos em grupos aminas foram obtidos em condições em que a concentração de espécies CN nos plasma da mistura de EDA e C2H2 era menor. Os filmes ricos em grupos nitrogenados, produzidos através de plasmas da mistura de EDA e C2H2, apresentaram baixa solubilidade em água.
Plasma polymers obtained by plasma polymerization of diethyleneglycol dimethyl-ether (diglyme), 2-methyl-2-oxazoline (oxazoline) and the mixture of ethylenediamine (EDA) with acetylene (C2H2) were produced in low pressure conditions. These materials might have a set of essential properties to biomedical applications. The plasmas were analyzed by Langmuir probe technique (LP) and optical emission spectroscopy (OES) techniques. Polymer characterization was performed by contact angle and surface energy analysis (AC and ES), atomic force microscopy (AFM), confocal microscopy (MC) and Fourier transform infrared spectroscopy (FTIR). In order to obtain details of polymerization process, plasma characteristics were correlated to polymers properties in order to control the production of materials with desired characteristics. The cold electron temperatures were observed between 0.2 and 1.6 eV and the plasmas densities about 10-15 m -3 . The electronic temperature behavior was analyzed as a function of operating pressure and applied power. This behavior was linked to production of CH, CO and Hα species in diglyme plasmas, CH, CN, CO and NH in 2- methyl-2-oxazoline plasmas and CN, CH and NH species in plasmas of EDA and C2H2 mixture. The mean roughness investigation, the bonds observed by FTIR technique and the deposition rates revealed the role of these species on polymerization processes. The CO species in diglyme plasmas and CN species in plasmas of EDA and C2H2 mixture were responsible for production of volatile groups both in the growing polymers surface and in suspension. In the plasma polymerization process of 2-methyl-2-oxazoline this feature was not observed. On the contrary, high deposition rates, decreasing of closed oxazoline rings amount in plasma polymers and at least three kinds of oxygen bonds were observed, showing that the plasma polymerization process was able to perform the ring opening process and fragmentation of monomer molecules. The cross-link structures and amount of polar groups on the plasma polymers surface were assigned to the thin films hydrophilic character. High concentrations of polar groups in 2-methyl-2-oxazoline plasma polymers were responsible to low contact angle values, around 10o , and the amount of nitrogen groups (amines) in plasmas polymers of EDA and C2H2 mixture were closely related to contact angle behavior. Plasma polymers with higher amounts of amine groups were obtained under conditions in which low CN concentrations was observed on plasmas of EDA and C2H2 mixture. The nitrogen-rich films, produced by plasma polymerization of EDA and C2H2 mixture, presented low solubility in water
Plasma polymers obtained by plasma polymerization of diethyleneglycol dimethyl-ether (diglyme), 2-methyl-2-oxazoline (oxazoline) and the mixture of ethylenediamine (EDA) with acetylene (C2H2) were produced in low pressure conditions. These materials might have a set of essential properties to biomedical applications. The plasmas were analyzed by Langmuir probe technique (LP) and optical emission spectroscopy (OES) techniques. Polymer characterization was performed by contact angle and surface energy analysis (AC and ES), atomic force microscopy (AFM), confocal microscopy (MC) and Fourier transform infrared spectroscopy (FTIR). In order to obtain details of polymerization process, plasma characteristics were correlated to polymers properties in order to control the production of materials with desired characteristics. The cold electron temperatures were observed between 0.2 and 1.6 eV and the plasmas densities about 10-15 m -3 . The electronic temperature behavior was analyzed as a function of operating pressure and applied power. This behavior was linked to production of CH, CO and Hα species in diglyme plasmas, CH, CN, CO and NH in 2- methyl-2-oxazoline plasmas and CN, CH and NH species in plasmas of EDA and C2H2 mixture. The mean roughness investigation, the bonds observed by FTIR technique and the deposition rates revealed the role of these species on polymerization processes. The CO species in diglyme plasmas and CN species in plasmas of EDA and C2H2 mixture were responsible for production of volatile groups both in the growing polymers surface and in suspension. In the plasma polymerization process of 2-methyl-2-oxazoline this feature was not observed. On the contrary, high deposition rates, decreasing of closed oxazoline rings amount in plasma polymers and at least three kinds of oxygen bonds were observed, showing that the plasma polymerization process was able to perform the ring opening process and fragmentation of monomer molecules. The cross-link structures and amount of polar groups on the plasma polymers surface were assigned to the thin films hydrophilic character. High concentrations of polar groups in 2-methyl-2-oxazoline plasma polymers were responsible to low contact angle values, around 10o , and the amount of nitrogen groups (amines) in plasmas polymers of EDA and C2H2 mixture were closely related to contact angle behavior. Plasma polymers with higher amounts of amine groups were obtained under conditions in which low CN concentrations was observed on plasmas of EDA and C2H2 mixture. The nitrogen-rich films, produced by plasma polymerization of EDA and C2H2 mixture, presented low solubility in water
Descrição
Palavras-chave
Plasma, Dietilenoglicol dimetil-eter, 2-metil-2-oxazolina, Etilenodiamina, Espectroscopia ótica de emissão, Sonda de Langmuir, Ângulo de contato e energia de superfície, Microscopia de força atômica, Microscopia confocal, Espectroscopia infravermelha por transformada de Fourier, Processos de polimerização, Optical emission spectroscopy, Polymerization processes, Fourier transform infrared spectroscopy, Contact angle and Surface Energy, Confocal microscopy, Atomic force microscopy, Polimerização, Microscopia de infravermelho