Ladder polymers are a type of polymeric structure characterized by their unique arrangement, which resembles a ladder. In these materials, the polymer chains are structured with rigid backbones and are connected by side groups or links that form steps in the "ladder." This configuration can lead to distinctive properties, such as high thermal stability, rigidity, and resistance to solvents and chemicals.
"Macromolecules" is a scientific journal that publishes research articles and reviews in the field of polymer science and macromolecular chemistry. It is recognized for contributing to the understanding of the chemistry, physics, and engineering of macromolecules, including synthetic and natural polymers.
A macromonomer is a type of compound that features both characteristics of macromolecules (such as polymers) and small molecules (monomers). Typically, a macromonomer has a moderate molecular weight and often contains functional groups that allow it to react and participate in polymerization processes. Macromonomers can serve as building blocks for the synthesis of larger polymeric structures, contributing to the formation of various materials with desired properties.
The Mark–Houwink equation describes the relationship between the intrinsic viscosity \([η]\) of a polymer solution and the molecular weight \(M\) of the polymer. This empirical relationship is significant in polymer science as it provides insights into the size and shape of macromolecules in solution.
The Mayo–Lewis equation is a relationship used in polymer science to describe the relationship between the glass transition temperature (Tg) of a polymer and its molecular weight. It is particularly relevant when discussing polymers that exhibit glass transition behavior, which is the temperature range below which the polymer becomes brittle and behaves like a glass.
The Melt Flow Index (MFI) is a measure of the flow characteristics of a thermoplastic polymer when it is melted. It quantifies the ease of flow of the molten polymer through a standard die under a specific temperature and load. The MFI is typically expressed in grams per 10 minutes (g/10 min) and is determined using a standardized test method, often specified by organizations such as ASTM (American Society for Testing and Materials) or ISO (International Organization for Standardization).
A membrane osmometer is a scientific instrument used to measure osmotic pressure, which is the pressure required to stop the flow of solvent across a semipermeable membrane due to osmosis. Osmosis is the movement of solvent molecules (usually water) from a region of lower solute concentration to a region of higher solute concentration through a semipermeable membrane.
Methylaluminoxane (MAO) is a chemical compound that is often used as a cocatalyst in the production of certain types of polymerization reactions, particularly in the field of olefin polymerization. It is an aluminum-based compound and is primarily known for its role in activating specific metal catalysts, such as those based on transition metals, to produce high-performance polymers like polyethylene and polypropylene.
Micro-compounding generally refers to the process of creating very small-scale compounded pharmaceuticals or formulations that are typically prepared by a licensed pharmacist or a specialized compounding pharmacy. This practice allows for the customization of medications to meet the unique needs of individual patients, such as altering dosage forms, flavors, or delivery methods.
Molar mass distribution, also known as molecular weight distribution, refers to the variation in the molar mass (or molecular weight) of a sample of polymers or other complex mixtures. This distribution is important because it reflects the diversity in the size of molecules within a sample, which can significantly affect the physical, chemical, and mechanical properties of a material.
Nanofiber seeding is a technique used in tissue engineering and regenerative medicine, where nanofibers are employed as scaffolds to support the growth of cells and tissues in vitro or in vivo. This method leverages the unique properties of nanofibers, such as their high surface area, porosity, and ability to mimic the extracellular matrix (ECM) of natural tissues, to enhance cellular behavior and tissue regeneration.
An oligomer is a molecular structure that consists of a small number of monomer units (the individual building blocks) linked together. The term “oligomer” typically refers to compounds made up of between 2 and about 10 monomers, though the exact definition can vary depending on the context or field of study.
Phase inversion in chemistry refers to the process where the dominant phase of a multiphase system changes from one type to another, typically between a continuous phase and a dispersed phase. This phenomenon commonly occurs in emulsions, suspensions, and colloidal systems. For instance, in an emulsion, one liquid (the dispersed phase) is distributed in another liquid (the continuous phase). Initially, the system may have oil as the dispersed phase in water (oil-in-water emulsion).
The Phillips catalyst refers to a specific type of catalyst used in the polymerization of ethylene to produce polyethylene, developed by a team of researchers at Phillips Petroleum Company in the 1950s. This catalyst is a chromium-based catalyst, typically chromium oxide, supported on silica. The Phillips catalyst is notable for its ability to produce low-density polyethylene (LDPE) and has significant industrial importance due to its efficiency in converting ethylene into high molecular weight polyethylene.
Photografting is a technique used in material science and polymer chemistry to modify surfaces or create new functionalities on materials at the molecular level through photochemical processes. This method typically involves the use of light to initiate chemical reactions that result in the attachment of polymer chains or functional groups to a substrate.
Plastarch material, often abbreviated as PSM, is a biodegradable thermoplastic material derived from renewable resources, primarily corn starch. It belongs to a group of bioplastics that are designed to provide an environmentally friendly alternative to traditional petroleum-based plastics. PSM exhibits properties similar to conventional plastics, making it suitable for a variety of applications, including packaging, disposable utensils, and other consumer products.
Poly(p-phenylene) is a type of conducting polymer, which consists of a linear chain of repeating units derived from para-substituted phenylene units. Its chemical structure is characterized by alternating single and double carbon-carbon bonds in the backbone, leading to a conjugated system that allows for electrical conductivity.
Poly(pentafluorophenyl acrylate) is a polymer derived from the polymerization of pentafluorophenyl acrylate, which is an acrylate monomer containing a pentafluorophenyl group. The "pentafluorophenyl" refers to a phenyl ring (a six-carbon aromatic ring) that has five of its hydrogen atoms replaced with fluorine atoms.
Poly(phthalaldehyde) (PPA) is a thermoplastic polymer known for its unique properties, such as high rigidity, thermal stability, and good chemical resistance. It is derived from phthalaldehyde, a compound that can polymerize to form this high-performance material. PPA has been studied for various applications, including in the production of engineering plastics and coatings, as well as composite materials. Its advantages include a high glass transition temperature and the ability to maintain mechanical strength at elevated temperatures.
Polyaddition is a type of chemical reaction in which monomers with multiple reactive functional groups react to form a polymer without the elimination of any small molecules. This process typically involves the stepwise addition of monomer units, each containing at least two reactive sites, leading to the formation of a high molecular weight polymer.