Monodisperse sub-200nm polystyrene nanoparticles were synthesized by a facile one-step emulsion polymerization technology using sodium dodecyl sulfonate (SDS) and 2, 2′-azobis (2-methylpropionamide) dihydrochloride (AIBA) as the surfactant and initiator, respectively. The in situ neutralization between negatively charged surfactant SDS and positively charged AIBA was used to control the primary particle (or swollen micelle) volume and the extent of the particle coagulation. As the oligomeric radicals with cationic AIBA chain ends were captured by anionic swollen micelles, the electrostatic stability of swollen micelles gradually reduced, further promoting the primary particle coagulation. As a result, the initial particle number decreased with the addition of AIBA. The earlier primary particle coagulation not only enlarged the particle size, but also narrowed the particle size distribution of the final latex particles. This approach was easy to scale-up as a facile industrial technology to produce monodisperse polymeric nanoparticles on large scale.
Keywords: Emulsion polymerization; Nanoparticle; Monodisperse; Particle coagulation; AIBA
1. Introduction
Emulsion polymerization technology is widely applied in many fields including synthetic rubber, thermoplastics, coating, adhesive, and plastic modifier [1–4]. Much of the interest in it derives from the possibilities for the preparation of monodisperse or functional latex particles [5,6]. Until today, the challenges
To keep it as simple as possible, (K.I.S.S.) this topic involves the study of: 1. POLYMERS FROM PETROCHEMICALS & BIOMASS
Polymers are formed through a process of polymerisation reactions (10), the most common reaction types being addition and condensation reactions (10). In an addition polymerisation reaction (Figure 1), double-bonded hydrocarbons (alkenes) react together to break their double bonds and covalently bond to form monomers (10). Highly branched molecules have the inability to 'line up' with one another which causes an amorphous solid, which does not have a predictable arrangement or repeating pattern (10). Long-chain molecules have regular and repeating structure which causes cyrstallinity, due to the increased attraction of intermolecular forces (10). Condensation reactions occur when a hydrocarbon molecule also contains oxygen, where two functional groups containing hydrogen are present on each molecule (10). These molecules form a dimer when attached together which then combine to create a polymer, and results in a water product
In normal micelles, the hydrophobic hydrocarbon chains of the surfactants are directed toward the internal of the micelle, and the hydrophilic groups of the surfactants are in contact with the surrounding aqueous middle. Above the cmc, the physical state of the surfactant molecules changes significantly, and extra surfactant exists as aggregates or micelles. The bulk attributes of the surfactant change around the cmc, such as osmotic pressure, turbidity, solubilization, surface tension, conductivity, and selfdiffusion. On the other hand, reverse micelles are formed in nonaqueous medium where
This seminar was presented by Dr. Robert B. (Barney) Grubbs, who is an Associate Professor of the Department of Chemistry at Stony Brook University. Also, Dr. Grubb has been a professional scientist at the Center for Functional Nanomaterials at the Brookhaven National Laboratory (2009-2014). On his presentation Dr. Grubbs explained how, through synthesis it is possible to control the structure and properties of molecules to create functional materials. In order to obtain these functional materials, Dr. Grubbs and his research group have synthesized block and star-block copolymers, which depending on their properties can be used in different applications.
Conventional surfactants (monomeric surfactants) contain both hydrophobic group (hydrocarbon chain) and hydrophilic group (polar head) in the same surfactant molecule. In recent years, the dimeric surfactants known as gemini surfactants have generated attention in the academic and various industrial applications [3-6]. Gemini surfactants represent a new class of surfactants made up of two identical or different amphiphilic moieties having the structure of conventional (monomeric) surfactants connected by a spacer group and display greater surface activity in the same molar concentration. Their cmc values are smaller than those of monomeric surfactants with equivalent chain lengths. As single-chained surfactants form spherical micelles in aqueous solutions, double-changed surfactants form bilayer or worm-like type micelles [7, 8].
Alkenes—referred to as olefins due to their oil forming tendency with chlorine—play an important role in the production of polymers. The work by Ziegler and Natta on the catalysts for polymerization of alkenes established the roots of the polymer industry. However, a major catalyst to its growth was the great discovery made by Grubbs, Schrock and Chauvin that won them the Nobel Prize in Chemistry in 2005—olefin metathesis.
Polymerization is when two monomer molecules join together to form a larger polymer monomer molecule or a chain of lager polymer molecules. This chemical reaction takes place through dehydration synthesis. Dehydration synthesis is when water is removed to make it able for monomers to join of bond together. The four major group of biochemical: carbohydrates, nucleic acid, lipids, and proteins share properties with polymerization of the macromolecules. Therefore completed macromolecules depend on properties of single monomers and their sequence.
The history of polymers stretch back millions of years. These “primitive” polymers were created by nature to fulfill the needs of information storage, energy storage and information reproduction. Human made polymers are a more recent invention, of the last two hundred years or so. These polymers are general made of highly flammable hydrocarbons and their derivatives. Fires caused by a combination of human careless and the physical properties of hydrocarbons have caused millions of dollars in property damage and claimed an untold number of human lives. It is this fact that has lead to scientists devoting time and resources to making polymers safer. In the following paragraphs the mechanism behind burning polymers will be
Polymeric materials are consumed on the order of three million metric tons per year and account for the high standard of living in the developed world. For most applications, these materials must be plasticized. Traditionally, phthalate esters, owing both to cost and effectiveness, have been popular plasticizers. However, these materials may migrate from the host polymer, particularly for waste items discarded in a landfill, and enter the environment. They may bioaccumulate become part of the human diet and contribute to various negative health effects. As a consequence, new environmentally-benign plasticizers are being sought.
Colloidal drug carriers offer a number of potential advantages as delivery systems for, weakly soluble compounds. The first generation of colloidal carriers, in particular liposomes and submicron-sized lipid emulsions are, however, associated with several drawbacks which so far have prevented the wide use of these carriers in drug delivery. As an alternative colloidal delivery system melt emulsified nanoparticles based on solid lipids have been proposed. Careful physicochemical characterization has demonstrated that these lipid-based nanosuspensions (solid lipid nanoparticles) are not just emulsions with solidified droplets. Colloidal drug carriers such as liposomes and nanoparticles can be used to improve the therapeutic
The report firstly introduced Acrylonitrile butadiene Styrene copolymers(ABS) basic information included Acrylonitrile butadiene Styrene copolymers(ABS) definition classification application industry chain structure industry overview; international market analysis, China domestic market analysis, Macroeconomic environment and economic situation analysis and influence, Acrylonitrile butadiene Styrene copolymers(ABS) industry policy and plan, Acrylonitrile butadiene Styrene copolymers(ABS) product specification, manufacturing process, product cost structure etc.
In this study, we describe a versatile strategy to fabricate newly-fashioned silica-modified membranes based on organic/inorganic hybridization for oil/water emulsion separation. The silica-modified membranes were easily obtained by a simple two-step immersion of polysulfone hollow fiber membranes into silicon solution of tetraethyl orthosilicate mixed with 3-glycidyloxypropyltrimethoxysilane, and subsequently into lactic acid solution. Attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy were used to characterize the compositions and structures of the membranes. A micronanoscaled SiO2-based coating was generated roughly and continuously on
Colloidal particles in wastewater suspension normally carry an overall negative charge on their surface that led to electrostatic repulsion. This electrostatic repulsionresult is the stabilization of the suspension as it prohibits the particles to come together and form agglomerate. Flocculants are thus added to change the surface property of such particles and destabilize the suspension so as to facilitate the separation of the solids (Tripathy and Ranjan De 2006). Protein based flocculantsdevelopment for wastewater treatment is mainly built on theirpolyampholite nature associated with the functional groups of the composing amino acids. Most studies in the literature base their protein flocculation mechanisms(Seki et al. 2010, Piazza and Garcia 2013) on theories developed for synthetic polymeric flocculants, such as polyacrylamide. Flocculation mechanisms that could be relevant for protein based flocculants include: (1) Coagulation, (2) Electrostatic patch flocculation and (3) Polymer bridging(Gregory 1973, Sharma et al. 2006, Hjorth and Jorgensen 2012).
This half-an-hour process involves the deposition of a layer of APTES at the channel surface. This opens a route for the facile derivatization of the modified PDMS surface with small organic molecules or biomolecules, in a manner analogous to the use of silanized glass or metal oxide substrates. The methodology offers significant advantages, including reduced reaction times and equipment requirements compared to processes such as removing uncured oligomers by curing PDMS for a longer time [Eddington et al, 2006] and monomer grafting. It is inexpensive and suitable for commercial adoption [John Beal et al,
A polymer is a large molecule consisting of many smaller subunits known as monomers. There are different types of polymers and many uses for all of them. Even though people may not realize it polymers play an essential role in our everyday life. For polymers range from plastics, PVC, and Styrofoam to key structures in the human body like DNA and proteins which are key components to the human body that makes it possible for each of us to live and be unique. So with out polymers in our body we would be dead, and with out them in our society it would be a drastically changed for the worse to say the least