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Abstract(s)
Os Óleos Essenciais (OE) são uma mistura de compostos hidrofóbicos voláteis que
se degradam facilmente, porém apresentam propriedades e aplicações bastante
úteis ao Homem desde o início das civilizações. O nanoencapsulamento destas
substâncias tem vindo a ganhar um elevado interesse, essencialmente pelos
benefícios que apresenta face aos microssistemas e proteção contra as condições
ambientais, mas também pela variedade de materiais que se podem utilizar
como agentes de encapsulamento. As estratégias atuais de nanoencapsulamento
tendem cada vez mais para uma Química Verde e sustentável, de modo a deixar
uma pegada ecológica mais pequena.
O presente trabalho pretende realizar o encapsulamento de óleos essenciais em
nanocápsulas de Poli(Etileno Glicol) (PEG), pelo método de emulsão de óleo em
água (O/A), e estudar a influência da massa molecular do PEG utilizado (do
monómero até PEG 35 000) na formação das nanocápsulas. As amostras obtidas
foram caraterizadas por Microscopia Eletrónica. A resistência das nanoemulsões
de nanocápsulas (NC) à turbulência e à temperatura foi estudada por
centrifugação e por aumento de temperatura gradual a pressão reduzida.
Observou-se que PEG com massa molar de 1 500 até 6 000 g/mol origina sistemas
de emulsões de NC espessas e estáveis, com elevada resistência à turbulência e à
temperatura. O Etilenoglicol, ou seja, o monómero (MEG), nas condições
estudadas parece polimerizar em torno de gotículas de OE, formando
nanocápsulas, mas em baixa concentração. O PEG 300, líquido à temperatura
ambiente, forma nanocápsulas também em baixa quantidade, apenas observáveis
por microscopia de transmissão.
O PEG com massas iguais ou superiores a 12 000 g/mol formam sistemas de
microemulsões estáveis, mas não formam nanocápsulas. Concluiu-se ainda que a
adição de etanol, apesar de aumentar a concentração de nanocápsulas diminui a
espessura das cápsulas, deixando-as frágeis e pouco resistentes.
Essential Oils (EO) are a mixture of volatile hydrophobic compounds that degrade easily, but have properties and applications very useful to man since the beginning of human civilizations. The nanoencapsulation of these substances has gained a relevant interest, essentially for the benefits it provides face to microsystems and protection against environmental conditions, but also by the variety of materials that can be used as encapsulating agents. Current strategies of nanoencapsulation tend increasingly for Green Chemistry and sustainable methods, for a smaller ecological footprint. This work pretends to perform the encapsulation of essential oils in nanocapsules of Poly (Ethylene Glycol) (PEG), by the method of Oil in Water emulsion (O/W), and study the influence of molecular weight of PEG (monomer to PEG 35 000) on the formation of nanocapsules. The samples were characterized by Electronic Microscopy techniques. Nanoemulsions and nanocapsules stability was studied by centrifugation (resistance to turbulence) and by gradual increase of temperature in a low pressure system. It was observed that PEG with molar weight from 1500 t0 6 000 g/mol affords emulsions of uniform nanocapsules, thick and stable systems with high resistance to turbulence and temperature. The monomer (MEG) polymerizes around the OE droplets forming NC in a not significant amount. PEG 300, liquid at room temperature, also forms NC in small amounts. PEG with molar weights equal to or greater than 12 000 g / mol form stable microemulsions systems with no formation of NC. It was also concluded that the addition of ethanol, despite increasing the encapsulation efficiency, decreases the thickness of the capsules, making them fragile and much less resistant.
Essential Oils (EO) are a mixture of volatile hydrophobic compounds that degrade easily, but have properties and applications very useful to man since the beginning of human civilizations. The nanoencapsulation of these substances has gained a relevant interest, essentially for the benefits it provides face to microsystems and protection against environmental conditions, but also by the variety of materials that can be used as encapsulating agents. Current strategies of nanoencapsulation tend increasingly for Green Chemistry and sustainable methods, for a smaller ecological footprint. This work pretends to perform the encapsulation of essential oils in nanocapsules of Poly (Ethylene Glycol) (PEG), by the method of Oil in Water emulsion (O/W), and study the influence of molecular weight of PEG (monomer to PEG 35 000) on the formation of nanocapsules. The samples were characterized by Electronic Microscopy techniques. Nanoemulsions and nanocapsules stability was studied by centrifugation (resistance to turbulence) and by gradual increase of temperature in a low pressure system. It was observed that PEG with molar weight from 1500 t0 6 000 g/mol affords emulsions of uniform nanocapsules, thick and stable systems with high resistance to turbulence and temperature. The monomer (MEG) polymerizes around the OE droplets forming NC in a not significant amount. PEG 300, liquid at room temperature, also forms NC in small amounts. PEG with molar weights equal to or greater than 12 000 g / mol form stable microemulsions systems with no formation of NC. It was also concluded that the addition of ethanol, despite increasing the encapsulation efficiency, decreases the thickness of the capsules, making them fragile and much less resistant.
Description
Keywords
Nanoemulsão. Nanoencapsulamento Óleo Essencial Poli(Etilenoglicol) (Peg)