Synthetic strategies for polymer-based nanocomposites particles

Authors: A.C.C. Esteves and A.M.V. Barros-Timmons. The current chapter focuses on synthetic approaches reported in the last decade regarding the preparation of polymer based nanocomposite particles, featuring potential bio-applications. In composite materials especial attention must be devoted to interfaces in order to improve the compatibility between the inorganic/organic components. Hence the main approaches for the surface modification of inorganic particles are firstly described. Secondly, chemical strategies involving the in situ preparation of one of the composite components are reviewed through typical examples from the recent literature. The advantages and drawbacks of each approach are discussed and the high potential of chemical methods to prepare an enormous variety of polymer based nanocomposites are highlighted. Particular emphasis is given to the recent controlled/living polymerization methods which allow preparing the polymer component with controlled characteristics, directly from the surface of the inorganic nanoparticles. Finally the functionalization of polymer based nanocomposites for prospective bio-applications is addressed

Synthetic strategies for polymer-based nanocomposites particles

Authors: A.C.C. Esteves and A.M.V. Barros-Timmons. The current chapter focuses on synthetic approaches reported in the last decade regarding the preparation of polymer based nanocomposite particles, featuring potential bio-applications. In composite materials especial attention must be devoted to interfaces in order to improve the compatibility between the inorganic/organic components. Hence the main approaches for the surface modification of inorganic particles are firstly described. Secondly, chemical strategies involving the in situ preparation of one of the composite components are reviewed through typical examples from the recent literature. The advantages and drawbacks of each approach are discussed and the high potential of chemical methods to prepare an enormous variety of polymer based nanocomposites are highlighted. Particular emphasis is given to the recent controlled/living polymerization methods which allow preparing the polymer component with controlled characteristics, directly from the surface of the inorganic nanoparticles. Finally the functionalization of polymer based nanocomposites for prospective bio-applications is addressed

Nanocompósitos de matriz polimérica: estratégias de síntese de materiais híbridos

Associating the well known advantages of hybrid materials to the wide potential of nanomaterials, the new and featuring class of polymer nanocomposites turned into one of the most intensively researched areas. This review highlights recent developments in the field of the synthesis of polymer based nanocomposites. Important issues related to the surface modification of fillers, in order to promote the compatibility between the inorganic/organic components, are also reported. The enhancement of the physical properties and the potential applications of polymer nanocomposites are considered in typical examples, given for each synthetic method described

Nanocompósitos de matriz polimérica: estratégias de síntese de materiais híbridos

Associating the well known advantages of hybrid materials to the wide potential of nanomaterials, the new and featuring class of polymer nanocomposites turned into one of the most intensively researched areas. This review highlights recent developments in the field of the synthesis of polymer based nanocomposites. Important issues related to the surface modification of fillers, in order to promote the compatibility between the inorganic/organic components, are also reported. The enhancement of the physical properties and the potential applications of polymer nanocomposites are considered in typical examples, given for each synthetic method described

Preparation and characterization of hybrid organic/inorganic nanocomposites by in situ minemulsion polymerization

SiO2/polystyrene nanocomposite particles were synthesized via miniemulsion polymerization using sodium dodecyl sulfate (SDS) as surfactant and hexadecane as hydrophobe in the presence of silica particles coated with methacryloxy(propyl)trimethoxysilane (MPS) surface coupling agent. The silica particles were individually coated with polymer yielding a very homogenous nanocomposite latex which was very stable in a wide range of ionic strengths. Monomer conversion was reasonably high and fast

Polymer encaopsulation of CdE (E= S, Se) quantum dots ensembles via in situ radical polymerization in miniemulsion

Cadmium sulfide and cadmium selenide/polymer nanocomposites were prepared via in-situ radical polymerization in miniemulsion. Organically capped CdE (E = S, Se) quantum dots (QDs) were used as the starting materials and ensembles of these dots were encapsulated with no need of further surface treatment. The use of two polymer matrices was investigated: polystyrene (PS) and poly(n-butyl acrylate) (PBA). In both cases, homogenous nanocomposites were obtained and their optical properties were investigated by visible absorption and photoluminescence spectroscopy. Quantum size effects were assigned to the nanocomposites, indicating the integrity of the individual QDs upon polymer encapsulation using the miniemulsion process

Hopping conduction on PPy/SiO2 nanocomposites obtained via in situ emulsion polymerization

This work describes the preparation and electrical characterization of conducting polypyrrole (PPy) and silica nanocomposites. Four samples were investigated: (i) pure PPy, (ii) PPy-covered SiO2 spherical nanoparticles, (iii) PPy-covered SiO2 spherical nanoparticles modified with 3-aminopropyltriethoxysilane (APS), and (iv) PPy-covered SiO2 fibers. Structural characterization was made by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical conductivity was measured from 80 K to 300 K and three-dimensional variable range hopping conduction was observed. From the hopping parameter the mean hopping distance was obtained as well as the density of active center and the energy associated with it

Langmuir films from tailor-made semi-amphiphilic alternating (AB) heterocyclic copolymers

Alkyl-substituted polyheterocycles (cf. poly(3-alkylthiophene) and poly(N-alkylpyrrole)) do not form true monomol. films at the air-H2O interface, due to lack of the required hydrophobic-hydrophilic balance. The authors designed and synthesized 2 new semi-amphiphilic alternating (AB) heterocyclic copolymers via a Stille coupling route, to study their film forming properties at the air-H2O interface, as inferred through surface pressure-area isotherms and Brewster angle microscopy. The copolymers I and II possess a N-alkylpyrrole unit, alternated with phenylene and benzothiadiazole units, resp. While copolymer-I formed a stable multilayer stack, copolymer-II forms a monomol. monolayer, at the air-H2O interface. The Langmuir film of copolymer-II could also be transferred layer-by-layer onto a substrate by vertical dipping metho

Synthetic strategies for polymer-based nanocomposites particles

Authors: A.C.C. Esteves and A.M.V. Barros-Timmons. The current chapter focuses on synthetic approaches reported in the last decade regarding the preparation of polymer based nanocomposite particles, featuring potential bio-applications. In composite materials especial attention must be devoted to interfaces in order to improve the compatibility between the inorganic/organic components. Hence the main approaches for the surface modification of inorganic particles are firstly described. Secondly, chemical strategies involving the in situ preparation of one of the composite components are reviewed through typical examples from the recent literature. The advantages and drawbacks of each approach are discussed and the high potential of chemical methods to prepare an enormous variety of polymer based nanocomposites are highlighted. Particular emphasis is given to the recent controlled/living polymerization methods which allow preparing the polymer component with controlled characteristics, directly from the surface of the inorganic nanoparticles. Finally the functionalization of polymer based nanocomposites for prospective bio-applications is addressed

Polymer grafting from CdS quantum dots via AGET ATRP in miniemulsion

We report the synthesis of CdS quantum dot (QD)–poly(acrylate) nanocomposites using a recently developed catalytic system where activators are generated by electron transfer for atom-transfer radical polymerization (ATRP) in a miniemulsion. The QD surface was functionalized with a tris(alkyl)phosphine, previously modified with an ATRP chlorine initiator, and subsequent controlled polymerization was carried out from the functionalized surface of nanoparticles. The final material showed a high homogeneity and the QDs were evenly dispersed. The optical-absorption edge in the visible spectra of the nanocomposites attests the presence of the CdS QDs. Quantum confinement effects were assigned, though a blue shift in relation to the optical spectrum of the initial QDs has been observed