DEVELOPMENT OF NOVEL BACTERIAL CELLULOSE BASED MATERIALS FOR PROTON EXCHANGE FUEL CELLS

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Publications

Physicochemical surface properties of bacterial cellulose/polymethacrylate nanocomposites: an approach by inverse gas chromatography

Publication . Faria, Marisa; Vilela, Carla; Silvestre, Armando J.D.; Deepa, Bhanumathyamma; Resnik, Matic; Freire, Carmen S. R.; Cordeiro, Nereida

Nanocomposites of poly(glycidyl methacrylate) and bacterial cellulose (BC), or poly(poly(ethylene glycol) methacrylate) and BC were produced via the in-situ polymerization of methacrylic monomers, inside the BC 3D network. The nanocomposites surface properties were evaluated by inverse gas chromatography (IGC). The dispersive component of surface energy (γsd) varied between 35.64 - 83.05 mJ m-2 at 25 °C. The surface of the different nanocomposites has a predominant basic character (Kb/Ka = 4.20-4.31). Higher specific interactions with polar probes were found for the nanocomposite bearing pendant epoxide groups, that apart from the low surface area (SBET = 0.83 m2 g-1) and monolayer capacity (nm = 2.18 μmol g-1), exhibits a high value of γsd (88.19 mJ m-2 at 20 °C). These results confirm the potential of IGC to differentiate between nanocomposites with different surface functional groups and to predict their potential interactions with living tissues, body fluids and other materials.

2019Journal article

Open access

Poly(glycidyl methacrylate)/bacterial cellulose nanocomposites: preparation, characterization and post-modification

Publication . Faria, Marisa; Vilela, Carla; Mohammadkazemi, Faranak; Silvestre, Armando J.D.; Freire, Carmen S. R.; Cordeiro, Nereida

Nanocomposites composed of poly(glycidyl methacrylate) (PGMA) and bacterial cellulose (BC) were prepared by the in-situ free radical polymerization of glycidyl methacrylate (GMA) inside the BC network. The resulting nanocomposites were characterized in terms of structure, morphology, water-uptake capacity, thermal stability and viscoelastic properties. The three-dimensional structure of BC endowed the nanocomposites with good thermal stability (up to 270 °C) and viscoelastic properties (minimum storage modulus = 80 MPa at 200 °C). In addition, the water-uptake and crystallinity decreased with the increasing content of the hydrophobic and amorphous PGMA matrix. These nanocomposites were then submitted to post-modification via acid-catalysed hydrolysis to convert the hydrophobic PGMA into the hydrophilic poly(glyceryl methacrylate) (PGOHMA) counterpart, which increased the hydrophilicity of the nanocomposites and consequently improved their water-uptake capacity. Besides, the post-modified nanocomposites maintained a good thermal stability (up to 250 °C), viscoelastic properties (minimum storage modulus = 171 MPa at 200 °C) and porous structure. In view of these results, the PGMA/BC nanocomposites can be used as functional hydrophobic nanocomposites for post-modification reactions, whereas the PGOHMA/BC nanocomposites might have potential for biomedical applications requiring hydrophilic, swellable and biocompatible materials.

2019Journal article

Open access

Lipophilic phytochemicals from banana fruits of several Musa species

Publication . Vilela, Carla; Santos, Sónia A. O.; Villaverde, Juan J.; Oliveira, Lúcia; Nunes, Alberto; Cordeiro, Nereida; Freire, Carmen S. R.; Silvestre, Armando J.D.

The chemical composition of the lipophilic extract of ripe pulp of banana fruit from several banana cultivars belonging to the Musa acuminata and Musa balbisiana species (namely 'Chinese Cavendish', 'Giant Cavendish', 'Dwarf Red', 'Grand Nain', 'Eilon', 'Gruesa', 'Silver', 'Ricasa', 'Williams' and 'Zelig') was studied by gas chromatography-mass spectrometry for the first time. The banana cultivars showed similar amounts of lipophilic extractives (ca. 0.4% of dry material weight) as well as qualitative chemical compositions. The major groups of compounds identified in these fractions were fatty acids and sterols making up 68.6-84.3% and 11.1-28.0%, respectively, of the total amount of lipophilic components. Smaller amounts of long chain aliphatic alcohols and α-tocopherol were also identified. These results are a relevant contribution for the valorisation of these banana cultivars as sources of valuable phytochemicals (ω-3 and ω-6 fatty acids, and sterols) with well-established beneficial nutritional and health effects.

2014Journal article

Open access

Profiling of lipophilic and phenolic phytochemicals of four cultivars from cherimoya (Annona cherimola Mill.)

Publication . Santos, Sónia A. O.; Vilela, Carla; Camacho, João F.; Cordeiro, Nereida; Gouveia, Manuela; Freire, Carmen S. R.; Silvestre, Armando J.D.

The lipophilic and phenolic extractives of the ripe mesocarp of four cherimoya cultivars ('Perry Vidal', 'Mateus I', 'Mateus III' and 'Funchal') from Madeira Island, were studied for the first time. The predominant lipophilic compounds are kaurene diterpenes (42.2-59.6%), fatty acids (18.0-35.6%) and sterols (9.6-23.7%). Kaur-16-en-19-oic acid is the major lipophilic component of all cultivars accounting between 554 and 1350mgkg(-1) of dry material. The studied fruits also contain a high variety of flavan-3-ols, including galloylated and non-galloylated compounds. Five phenolic compounds were identified for the first time: catechin, (epi)catechin-(epi)gallocatechin, (epi)gallocatechin, (epi)afzelechin-(epi)catechin and procyanidin tetramer. 'Mateus I' and 'Mateus III' cultivars present the highest content of phenolic compounds (6299 and 9603mgkg(-1) of dry weight, respectively). These results support the use of this fruit as a rich source of health-promoting components, with the capacity to prevent or delay the progress of oxidative-stress related disorders.

2016Journal article

Open access

The ripe pulp of Mangifera indica L.: a rich source of phytosterols and other lipophilic phytochemicals

Publication . Vilela, Carla; Santos, Sónia A. O.; Oliveira, Lúcia; Camacho, João F.; Cordeiro, Nereida; Freire, Carmen S. R.; Silvestre, Armando J.D.

The chemical composition of the lipophilic extracts of the ripe pulp of mangoes from twelve cultivars of Mangifera indica L. from Madeira Island was investigated by gas chromatography–mass spectrometry (GC–MS) for the first time. The ripe pulp of these mango cultivars showed analogous amounts of lipophilic extractives, as well as sim ilar qualitative chemical compositions. The predominant compounds were free and glycosylated sterols and fatty acids, representing 44.8–70.7% and 22.6–41.9%, respectively, of the total amount of lipophilic components. Small er amounts of long chain aliphatic alcohols and α-tocopherol were also identified. These data indicate that the investigated mango cultivars are a rich source of valuable phytochemicals, contributing to the intake of at least 9.5–38.2 mg of phytosterols (free and glycosylated) and 0.7–3.9 mg of fatty acids (ω−3 and ω−6) per 100 g of fresh mango, with recognizable beneficial effects on human nutrition and health.

2013Journal article

Open access