Monosized cationic nanoparticles prepared by emulsifer-free emulsion polymerization (original) (raw)
Related papers
Asian Journal of Chemistry
Nanoparticles are defined as submicron-size solid between 100 to 500 nm that can be either biodegradable or non-biodegradable [1]. Nanoparticles can be constructed from various materials (e.g. polymers, lipids, metals, magnetic) and widely utilized in various industrial application like optical [2], catalyst [3], thermal [4], electrical [5], mechanical [6] and magnetic function [7]. In particular, polymeric nanoparticles have received great attention on account of their versatility in which they can host a wide range of active components including chemotherapeutics, contrast agents, proteins and nucleic acids, for various bio-medical applications [8]. The criteria for the ideal polymeric nanoparticles especially in the development of biomedical fields should be easy to synthesize, inexpensive, biocompatible and biodegradable, non-toxic and water soluble [9]. Hydrophilic polymer nanoparticles are the type of polymer chain that contains substitution of hydrophilic groups at the backbone either from anionic, cationic or amphoteric. This type of polymer can be divided into two main types, synthetic and natural. Nowadays, synthetic
Polymerization of methacrylate in a W/O microemulsion stabilized by a methacrylate surfactant
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999
A water-in-toluene microemulsion stabilized by the polymerizable surfactant didecyldimethylammonium methacrylate has been used to form polyelectrolyte particles. The microemulsion was photopolymerized using AIBN as the initiator, resulting in aggregates having hydrodynamic diameters of 11 nm, starting with 5 -6 nm initial nanodroplets with and without added sodium methacrylate (NaMA). The dried latexes have a diameter of 6 nm up to a [NaMA]/[surfactant] mole ratio (R) of 0.5, but 12 nm for R= 1.0. For R =0 -0.5, the maximum degree of polymerization was 50%, but it was 83% for R= 1.0. The polydispersity decreases with increasing R, while the film-forming tendency of the latexes increases.
European Polymer Journal, 2004
The influence of surfactant concentration on particle size and stability of nanocapsules with liquid cores, synthesized by an in situ miniemulsion polymerization process, was investigated. Although the role of surfactant in the synthesis of particles in the nanometer range has frequently been documented, the transition to structured particles, which almost consist of a 1:1 weight ratio of encapsulated liquid hydrophobe to polymeric shell, has not received much attention. Capillary hydrodynamic fractionation (CHDF) analyses were used to evaluate particle size. Results were subsequently used to stoichiometrically calculate the area which is occupied per surfactant molecule on the particle surface. These results were compared with ''classical'' miniemulsion data, i.e. data generated from the synthesis of polymeric latexes in the presence of a hydrophobe, but at a much lower hydrophobe:monomer ratio as was used here. The surface coverage per surfactant molecule could be related to the surface tension of the latex, thus providing a relationship between particle size and stability. CHDF was furthermore used to investigate particle size after grafting of a secondary PMMA shell. Data obtained from CHDF experiments were in all cases confirmed by TEM analysis of the synthesized particles. To conclude, the synthesis of nanocapsules with liquid cores could be successfully scaled-up, with retention of all the characteristics of the final latex.
Journal of Colloid and Interface Science, 2006
The polymerization of n-hexyl methacrylate (n-HMA) in three-component microemulsion stabilized with dodecyltrimethylammonium bromide (DTAB) is reported as a function of monomer and initiator concentrations and temperature. The obtained latices were bluish, transparent, and translucent. Particle sizes and molar masses were on the order of 20 nm and 3 × 10 6 g/mol, respectively. In all cases, high reaction rates and final conversions of 98% were obtained. Polymerization temperature has a strong effect on reaction rate and conversion.
Journal of Polymer Science Part A: Polymer Chemistry, 2004
Nanoscale poly(methyl methacrylate) (PMMA) particles were prepared by modified microemulsion polymerization. Different from particles made by traditional microemulsion polymerization, the particles prepared by modified microemulsion polymerization were multichain systems. PMMA samples, whether prepared by the traditional procedure or the modified procedure, had glass-transition temperatures (T g 's) greater than 120°C and were rich in syndiotactic content (55-61% rr). After the samples were dissolved in CHCl 3 , there were decreases in the T g values for the polymers prepared by the traditional procedure and those prepared by the modified process. However, a more evident T g decrease was observed in the former than in the latter; still, for both, T g was greater than 120°C. Polarizing optical microscopy and wide-angle X-ray diffraction indicated that some ordered regions formed in the particles prepared by modified microemulsion polymerization. The addition of a chain-transfer agent resulted in a decrease in both the syndiotacticity and T g through decreasing polymer molecular weight.
European Polymer Journal, 2004
In this study, MMA/BMA copolymer nanoparticles were synthesized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS) and initiated by potassium persulphate KPS. Maleic acid terminated poly(N-acetylethylenimine) (PNAEI) with two different chain lengths was also included in the recipe, as a cosurfactant and a comonomer. FTIR and 1 H-NMR proved incorporation of the macromonomer in the structure. High polymerization yields were achieved upto 98%. The viscosity average molecular weights of the copolymers were in the range of 2.77-5.50 · 10 5 . The glass transition temperatures of these copolymers were between 50.0 and 63.9°C. The average diameter of nanoparticles were in range of 40-96 nm. It was possible to produce nanoparticles smaller than 100 nm and with narrower size distributions by using much lower concentrations of SDS by including the macromonomers in the microemulsion polymerization recipe.
2011
Here, we present the oil/water (O/W) microemulsion polymerization in three-component microemulsions of n-butyl acrylate, ethyl acrylate, and methyl acrylate, monomers with similar chemical structures but different water solubilities using the cationic surfactant dodecyl trimethyl ammonium bromide. The effects of monomer water solubility, initiator type and initial monomer concentration on the polymerization kinetics were studied. Reaction rates were high with final conversions between 70 and 98% depending on the monomer and reaction conditions. The final latexes were bluish, with a particle size ranging between 20 and 50 nm and polymer with molar masses in the order of 10 6 g mol À1 . Increasing monomer water solubility resulted in a slower reaction rate, larger particles and a lower number density of particles. A higher reaction rate, larger average particle size and higher particle number density were obtained by increasing the monomer concentration.