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A monomer is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.
A polymer is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals.
In chemistry, a solution is a special type of homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. If the attractive forces between the solvent and solute particles are greater than the attractive forces holding the solute particles together, the solvent particles pull the solute particles apart and surround them. These surrounded solute particles then move away from the solid solute and out into the solution. The mixing process of a solution happens at a scale where the effects of chemical polarity are involved, resulting in interactions that are specific to solvation. The solution usually has the state of the solvent when the solvent is the larger fraction of the mixture, as is commonly the case. One important parameter of a solution is the concentration, which is a measure of the amount of solute in a given amount of solution or solvent. The term "aqueous solution" is used when one of the solvents is water.
Physical or chemical properties of materials and systems can often be categorized as being either intensive or extensive, according to how the property changes when the size of the system changes. The terms "intensive and extensive quantities" were introduced into physics by German mathematician Georg Helm in 1898, and by American physicist and chemist Richard C. Tolman in 1917.
In chemistry, a mixture is a material made up of two or more different chemical substances which are not chemically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions and colloids.
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called bipolymers. Those obtained from three and four monomers are called terpolymers and quaterpolymers, respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material.
In chemistry and biochemistry, an oligomer is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers. The name is composed of Greek elements oligo-, "a few" and -mer, "parts". An adjective form is oligomeric.
In chemistry, a molecule or ion is called chiral if it cannot be superposed on its mirror image by any combination of rotations, translations, and some conformational changes. This geometric property is called chirality. The terms are derived from Ancient Greek χείρ (cheir) 'hand'; which is the canonical example of an object with this property.
A solid solution, a term popularly used for metals, is a homogeneous mixture of two different kinds of atoms in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to describe the intimate mixing of components at the atomic level and distinguishes these homogeneous materials from physical mixtures of components. Two terms are mainly associated with solid solutions – solvents and solutes, depending on the relative abundance of the atomic species.
In polymer chemistry, branching is the regular or irregular attachment of side chains to a polymer's backbone chain. It occurs by the replacement of a substituent on a monomer subunit by another covalently-bonded chain of that polymer; or, in the case of a graft copolymer, by a chain of another type. Branched polymers have more compact and symmetrical molecular conformations, and exhibit intra-heterogeneous dynamical behavior with respect to the unbranched polymers. In crosslinking rubber by vulcanization, short sulfur branches link polyisoprene chains into a multiple-branched thermosetting elastomer. Rubber can also be so completely vulcanized that it becomes a rigid solid, so hard it can be used as the bit in a smoking pipe. Polycarbonate chains can be crosslinked to form the hardest, most impact-resistant thermosetting plastic, used in safety glasses.
In chemistry and fluid mechanics, the volume fraction is defined as the volume of a constituent Vi divided by the volume of all constituents of the mixture V prior to mixing:
A dispersion is a system in which distributed particles of one material are dispersed in a continuous phase of another material. The two phases may be in the same or different states of matter.
A telechelic polymer or oligomer is a prepolymer capable of entering into further polymerization or other reactions through its reactive end-groups. It can be used for example to synthesize block copolymers.
Miscibility is the property of two substances to mix in all proportions, forming a homogeneous mixture. The term is most often applied to liquids but also applies to solids and gases. An example in liquids is the miscibility of water and ethanol as they mix in all proportions.
In chemistry, coalescence is a process in which two phase domains of the same composition come together and form a larger phase domain. In other words, the process by which two or more separate masses of miscible substances seem to "pull" each other together should they make the slightest contact.
The upper critical solution temperature (UCST) or upper consolute temperature is the critical temperature above which the components of a mixture are miscible in all proportions. The word upper indicates that the UCST is an upper bound to a temperature range of partial miscibility, or miscibility for certain compositions only. For example, hexane-nitrobenzene mixtures have a UCST of 19 °C (66 °F), so that these two substances are miscible in all proportions above 19 °C (66 °F) but not at lower temperatures. Examples at higher temperatures are the aniline-water system at 168 °C (334 °F), and the lead-zinc system at 798 °C (1,468 °F).
An Interpenetrating polymer network (IPN) is a polymer comprising two or more networks which are at least partially interlaced on a polymer scale but not covalently bonded to each other. The network cannot be separated unless chemical bonds are broken. The two or more networks can be envisioned to be entangled in such a way that they are concatenated and cannot be pulled apart, but not bonded to each other by any chemical bond.
Reactive compatibilization is the process of modifying a mixed immiscible blend of polymers to arrest phase separation and allow for the formation of a stable, long-term continuous phase. It is done via the addition of a reactive polymer, miscible with one blend component and reactive towards functional groups on the second component, which result in the "in-situ" formation of block or grafted copolymers.
A miscibility gap is a region in a phase diagram for a mixture of components where the mixture exists as two or more phases – any region of composition of mixtures where the constituents are not completely miscible.
The methods for sequence analysis of synthetic polymers differ from the sequence analysis of biopolymers. Synthetic polymers are produced by chain-growth or step-growth polymerization and show thereby polydispersity, whereas biopolymers are synthesized by complex template-based mechanisms and are sequence-defined and monodisperse. Synthetic polymers are a mixture of macromolecules of different length and sequence and are analysed via statistical measures.
References
- ↑ Gert R. Strobl (1996). The Physics of Polymers Concepts for Understanding Their Structures and Behavior. Springer-Verlag. ISBN 978-3-540-60768-7. Section 3.2 Polymer Mixtures
- ↑ IUPAC , Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) " compatible polymer blend ". doi : 10.1351/goldbook.CT07581
- ↑ IUPAC , Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) " polymer blend ". doi : 10.1351/goldbook.P04736
