Growth of hydrogel nano- and microlayers covalently bounded onto PE surface

Silva, Rafael; Muniz, Edvani C.; Rubira, Adley F.

doi:10.1016/j.apsusc.2009.02.013

Cited by 12 publications

(7 citation statements)

References 36 publications

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“…PE was used as a substrate, since it is inert, cheap, and flexible. − Nonetheless, it is worth pointing out that any solid substrate could be potentially used. In addition, the previous surface treatment is not necessary to start the nanofabrication process.…”

Section: Resultsmentioning

confidence: 99%

Water Droplet Self-Assembly to Au Nanoporous Films with Special Light Trapping and Surface Electromagnetic Field Enhancement

Fragal

Rubira

et al. 2018

Langmuir

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Gold nano "breath figure" films are for the first time reported and their function as ideal systems for plasmonics demonstrated. Metal nano-breath figure substrates are metal thin films containing nanohole arrays supported on a solid substrate. Au nanohole arrays are prepared from the dynamic breath figure phenomenon, in which the pore formation is controlled to provide holes smaller than 100 nm. Au layer is deposited on polymer substrates containing breath figure topology. The breath figure topology can be fully translated to the Au layer. The nanofabrication process is completed within few minutes. A simplified preparation process but very impressive light trapping and surface electromagnetic field enhancement are related to the Au breath figure films obtained in this work. The porous films demonstrated higher absorbance in the region of 500−1100 nm than nonporous Au films. In the case of 10 nm Au film, the plasmon absorbance becomes more intense than the electronic band absorbance. The electromagnetic enhancement is proved by surface enhanced Raman spectroscopy effect, which is found to be very close to the maximum possible value predicted for nonresonant species.

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Section: Resultsmentioning

confidence: 99%

Water Droplet Self-Assembly to Au Nanoporous Films with Special Light Trapping and Surface Electromagnetic Field Enhancement

Fragal

Rubira

et al. 2018

Langmuir

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“…183,184 Na formação de compósitos, as modificações de superfícies são realizadas nas fibras lignocelulósicas na intenção de melhorar a compatibilidade com a matriz polimérica.…”

Section: Biocompósitos: Fibras Lignocelulósicas E Polímeros Biodegradunclassified

Aplicações de fibras lignocelulósicas na química de polímeros e em compósitos

2009

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Recebido em 19/1/09; aceito em 25/3/09; publicado na web em 2/4/09 APPLICATIONS OF LIGNOCELLULOSIC FIBERS IN POLYMER CHEMISTRY AND IN COMPOSITES. The use of lignocellulosic fibers and their constituents, as raw materials in the production of polymeric and composite materials, represent an exceptional opportunity of sustainable technological development. In the present report works that discuss promising alternatives of obtaining and use of materials such as cellulose, hemicellulose, lignin, cellulose nanocrystals and biocomposites were revised. The advance in the use of biomass can be, in a near future, capable of going beyond the application difficulties of these vast materials, especially in relation to the economical unviability, by the production of high performance polymeric and composite materials. This advance would represent a higher profitability to some areas of agrobusiness, especially the sector of biofuels, which produces elevated amounts of biomass waste.Keywords: lignocellulosic fibers; nanowhiskers; biocomposites. introduçÃoNos últimos anos tem surgido um grande interesse mundial no desenvolvimento de tecnologias "verdes" que possibilitem a utilização de produtos de menor impacto ambiental.1-4 A química "verde", como um todo, implica no desenvolvimento de processos químicos e produtos que levem a um ambiente mais limpo, saudável e sustentável. Neste contexto, os materiais plásticos sintéticos têm recebido especial atenção por conter em seus métodos de preparação questões que devem ser priorizadas. As questões que devem ser priorizadas são a não-biodegradabilidade dos plásticos sintéticos e por serem oriundos de fontes não-renováveis. 5-8Na busca pela sustentabilidade, várias pesquisas e trabalhos na área de materiais poliméricos e compósitos foram, e estão sendo, realizados para garantir a preservação ambiental e proporcionar um melhor padrão de vida à sociedade.9-13 Dentre as pesquisas nesta área, as que buscam a aplicação de recursos naturais na preparação dos materiais vêm crescendo, podendo-se destacar o uso de fibras naturais. [14][15][16][17][18][19][20][21][22] A Organização das Nações Unidas para a Agricultura e a Alimentação (FAO-ONU -Food and Agriculture Organization of the United Nations) declarou o ano de 2009 como o ano internacional das fibras naturais.23 A medida visa conscientizar e estimular a utilização de fibras naturais, encorajando políticas governamentais de incentivo ao setor e às ações empresariais sustentáveis, para a exploração dessas matérias-primas.Destaque ainda maior deve ser dado à utilização de fibras naturais de origem vegetal, em razão da enorme variedade de espécies passí-veis de serem pesquisadas. Diversas fibras vegetais são produzidas em praticamente todos os países e usualmente são designadas como materiais lignocelulósicos. Algumas fibras ocorrem espontaneamente na natureza, outras são cultivadas como atividade agrícola e ainda há aquelas que são resíduos gerados, principalmente, pela agroindústria. Na Tabela 1 pode ser verificada a produção anual das princ...

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“…19,20 This structure can not only provide a firm bonding between the hydrogel and the substrate to prevent delamination, but also eliminate the adverse effect of the poor mechanical strength of the thin hydrogel layer. 29 However, all these methods are complicated, and what's worse, the high reaction temperature or radiation makes it hard to introduce drugs into the hydrogel layer during its preparation, especially when it comes to active proteins. 27,28 For example, hydrogel nano-and microlayers were covalently bonded onto the prepared amine-functionalized polyethylene (PE) surface by the reaction of carboxylic acid groups with amine groups.…”

Section: Introductionmentioning

confidence: 99%

“…27,28 For example, hydrogel nano-and microlayers were covalently bonded onto the prepared amine-functionalized polyethylene (PE) surface by the reaction of carboxylic acid groups with amine groups. 29 However, all these methods are complicated, and what's worse, the high reaction temperature or radiation makes it hard to introduce drugs into the hydrogel layer during its preparation, especially…”

mentioning

confidence: 99%

Synthesis of pH-responsive hydrogel thin films grafted on PCL substrates for protein delivery

Zhang

Zhao

et al. 2015

J. Mater. Chem. B

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A new visible light induced graft polymerization method was utilized to prepare pH-sensitive hydrogel layers covalently attached to polymer substrates for drug delivery. In our strategy, isopropyl thioxanthone semi-pinacol (ITXSP) dormant groups were firstly introduced on the surface of a polycaprolactone (PCL) film by a UV-induced abstracting hydrogen-coupling reaction. Then visible light induced graft crosslinking polymerization was performed to initiate polymerization of poly(ethylene glycol) diacrylate (PEGDA) and acrylic acid (AA), resulting in the formation of a hydrogel layer. The thickness of the hydrogel film can be controlled by varying the exposure time and monomer composition. The grafted hydrogel layers showed a flat morphology and dense structure, which is different from the traditional reported porous structure. The water contact angle of the hydrogel layer exhibited a reversible change from 381 to 181 when the film was alternatively treated in buffers of pH 2.0 and 7.4, respectively. Patterned hydrogel layers were prepared as a model to determine the change in the height of the grafted hydrogel layer as a function of pH. As the pH changed from 2.0 to 7.4, the hydrogel pattern showed an increase in height due to the swelling of the hydrogel network, and the hydrogel layer formed by 0.2 wt% PEGDA and 25 wt% AA showed the most increase (30%) in height. Bovine serum albumin (BSA) and lysozyme as models of protein drugs were incorporated in the hydrogel network, and their release also showed obvious pH-sensitivity. At pH 2.0, hydrogels present a faster initial burst release due to the squeezing mechanism. Tertiary structure analysis showed that encapsulation and release did not affect the protein conformation. These findings have improved our understanding of hydrogel thin films, which may be useful as potential vehicles of therapeutic proteins in drug delivery applications. Scheme 1 Schematic illustration of the synthesis of a P(PEGDA/AA)/ protein hydrogel thin layer on the PCL film. (a) ITXSP was immobilized on the surface of the PCL substrate under UV irradiation. (b) Hydrogel layer was formed under visible light irradiation. (a 0 ) and (b 0 ) are the reaction mechanisms for steps (a) and (b), respectively.

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Growth of hydrogel nano- and microlayers covalently bounded onto PE surface

Cited by 12 publications

References 36 publications

Water Droplet Self-Assembly to Au Nanoporous Films with Special Light Trapping and Surface Electromagnetic Field Enhancement

Water Droplet Self-Assembly to Au Nanoporous Films with Special Light Trapping and Surface Electromagnetic Field Enhancement

Aplicações de fibras lignocelulósicas na química de polímeros e em compósitos

Synthesis of pH-responsive hydrogel thin films grafted on PCL substrates for protein delivery

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