What are the polymerization reactions? What are the types of polymerization reactions?

Polyaddition and polycondensation.

Polymerization reaction: It is divided into polyaddition reaction (polymerization reaction) and polycondensation reaction (condensation reaction).

1. The polymerization reaction mainly includes cationic polymerization, anionic polymerization, free radical polymerization and metal catalyst polymerization, which are suitable for different monomers. After the polymerization reaction is initiated by an initiator, the monomers are added to the top of the polymerization chain one by one to form polymers.

2. Polycondensation reaction can be divided into four categories according to reaction conditions: melt polycondensation, solution polycondensation, interface polycondensation and solid-phase polycondensation, and the monomer used in polycondensation reaction must have two or more functional groups. Generally, when monomers containing two functional groups are polycondensed, chain polymers are formed, and when monomers containing more than two functional groups are polycondensed, cross-linked bulk condensation polymers can be formed.

There are two types of differences: polyaddition (polymerization) and polycondensation (condensation).

1. The relationship between the disappearance of monomers and the polymerization time In the gradual polymerization reaction, the different functional groups of all monomers can react with each other, and the monomers disappear quickly, and the conversion rate should be expressed by the degree of reaction of the monomer functional groups p, and the relationship between them is the conversion rate = 100p. Whereas, in the chain polymerization reaction, the monomer gradually disappears.

2. The relationship between the average degree of polymerization and the conversion rate of polymers In the chain polymerization reaction, there is basically no dependence between the degree of polymerization and the conversion rate. In the stepwise polymerization reaction, only oligomers are formed at a conversion rate of 80%; Only when the conversion rate is 98%, the polymer can be formed, and the negative ion polymerization without chain termination and chain transfer can form a live polymer, and the click increases with the increase of the conversion rate.

The above content refers to Encyclopedia-Polyaddition Reaction.

The above content refers to Encyclopedia - Polycondensation Reaction.

The above content refers to Encyclopedia - Polymerization Reaction.

1. Polyaddition reaction (polymerization reaction).

That is, addition polymerization reaction, some compounds containing unsaturated bonds (double bonds, triple bonds, conjugated double bonds) or cyclic low molecular compounds, under the action of catalysts, initiators or radiation and other external conditions, the reaction of the same monomer to form new covalent bonds linked macromolecules is the addition reaction.

2. Polycondensation reaction (condensation reaction).

Refers to condensation polymerization. Condensation polymerization reaction is the full name of polycondensation reaction, which refers to the reaction of one or more monomers condensed with each other to form polymers, and its main product is called condensation polymer.

Safety measures that should be taken care of in the polymerization reaction:

1) A combustible gas detection alarm should be set up, which will automatically stop once it is found that there is a combustible gas leakage in the equipment and pipelines.

2) The stirring and temperature of the reactor should be detected and interlocked, and the feeding can be automatically stopped if abnormalities are found.

3) The high-pressure separation system should be equipped with rupture discs and detonators, and have a good electrostatic grounding system, and once there is an abnormality, the pressure should be relieved in time.

The polymerization reaction is divided into three categories: polycondensation, polyaddition, and ring-opening polymerization.

1. Polycondensation. Polycondensation is the abbreviation of condensation polymerization, which is the reaction of multiple condensation of monomers to synthesize polymers, in addition to the formation of polymers, there are also by-products of small molecules, such as water (synthesis of polyester), alcohol and other small molecules. Such as:

Synthesis of polyester, polycarbonate, phenolic resin, urea-aldehyde resin. Polycondensation reaction characteristics: the structural unit of the condensation polymer is several atoms less than that of the monomer.

2. Polyaddition. The reaction of hydrocarbon monomer bond breaking and then addition polymerization is called polyaddition reaction, such as polyethylene, polyvinyl chloride, etc. Polyaddition Reaction Characteristics:

The polymer band carries the same structural unit as the monomer, but the electronic structure changes, so the molecular weight of the polymer is an integer multiple of the molecular weight of the monomer.

3. Open-loop polymerization.

Cyclic monomers (e.g., propylene oxide) After the bond is broken, it polymerizes to form a polymer. Such as polyethylene oxide (PEG), polypropylene oxide (PPG).

Polymer. The compounds used to synthesize polymers are called monomers, which are transformed into building blocks in polymers through polymerization. Polymers formed by polymerization of a monomer, such as polyethylene, polypropylene.

Polymers formed by copolymerization of two or more monomers are called copolymers, such as polyester, polyamide, etc. The part of the monomer that remains in the polyosmotic stool complex molecule after the reaction is called the structural unit. Repeating units are the parts inside curly braces.

The polymerization reaction is.

The reaction of the polymerization of monomers into polymers. Polymerization with only one monomer is called homopolymerization, also known as polymerization. When the monomer polymerizes to form an oligomer with a small molecular weight, it is called a low polymerization reaction, and the product is called an oligomer.

When two or more monomers polymerize together, it is called copolymerization, and the product is called copolymer. From the perspective of polymerization reaction kinetics, there are two main types of polymerization reactions, one is chain polymerization reaction, such as addition polymerization of alkene monomers, referred to as polymerization. The second is the gradual polymerization reaction, such as the condensation polymerization between difunctional acids and diamines, referred to as polycondensation.

Lactic acid (IUPAC scientific name: 2-hydroxypropanolic acid) is a chemical compound, it is a carboxylic acid, its molecular formula is C3H6O3, the structure is simplified.

ch3ch(oh)cooh

It is a carboxylic acid that contains a hydroxyl group and is therefore an alpha hydroxy acid. Because it has both carboxyl and hydroxyl groups in its molecular structure, it can be polymerized. It can undergo a polycondensation reaction to form polymer compounds.

Polymerization is to break the double or triple bonds, and the leaked bonds are connected to the original other bond (if it is the same substance), and then connected in turn.

The definition of polymerization reaction will not be repeated. According to the definition of a polymerization reaction, if a monomer polymerizes to produce an oligomer with a low molecular weight, it may not become a polymer compound (the molecular weight of a polymer is usually large). So, it's not necessarily just the monomer that becomes a polymer.

The reaction process of synthesizing polymers from monomers. The low molecular weight raw materials with polymerization ability are called monomers, and the polymerization raw materials with large molecular weights are called macromolecular monomers.

Examples of polymerization reactions:

Polycondensation – monosaccharides form polysaccharides and amino acids form proteins.

Poly - most of the rubber.

Polymerization can occur under catalytic conditions.

Polyaddition. addition polymerization): i.e., addition polymerization.

Some compounds containing unsaturated bonds (double bonds, triple bonds, conjugated double bonds) or cyclic low molecular compounds are added to each other to form new covalent bonds under the action of catalysts, initiators or radiation.

The reaction of the attached macromolecules is the polymerization reaction. The reaction of the polymerization of alkene monomers by addition. There are no by-products in the polyaddition reaction. High school chemistry, especially elective 5, is often exposed. Generally speaking, the addition reaction refers to the chain growth polymerization reaction.

Such a reaction from a compound with a small relative molecular weight to an organic polymer compound with a relatively large molecular mass is called a polymerization reaction, and a polymerization reaction like ethylene to polyethylene is also called an addition polymerization reaction, referred to as a polyaddition reaction.

Polymerization is a reaction process in which polymers are synthesized from monomers. Polymerization reactions are divided into polycondensation reactions and polyaddition reactions.

Polyaddition reaction: that is, addition polymerization reaction, compounds containing unsaturated bonds (double bonds, triple bonds, conjugated double bonds) or cyclic low molecular compounds, under the action of catalysts, initiators or radiation and other external conditions, the reaction of the same monomer to form new covalently bonded macromolecules is the polyaddition reaction.

Polycondensation reaction: It is a monomer with two or more functional groups that reacts with each other to form polymer compounds, and at the same time produces simple molecules (eg.

H2O, Hx, alcohols, etc.).

Polymerization is defined as the process of converting low-molecular-weight monomers into high-molecular-weight polymers

Polymers have important properties such as plasticity, fiber formation, film formation, and high elasticity that low molecular weight monomers do not have, and can be widely used as plastics, fibers, rubbers, coatings, adhesives, and other applications. This material is composed of more than one structural unit (monomer), and is a polymer compound synthesized from monomers through repeated reactions.

There are four commonly used polymerization methods: bulk polymerization, suspension polymerization, solution polymerization and emulsion polymerization. Free radical polymerization can be performed with one of them; Ionic or coordination polymerization, generally using solution polymerization, for example, ethylene, propylene polymerization with titanium catalyst, because the catalyst and polymer are insoluble in solvents, often called slurry polymerization; The polycondensation reaction is generally carried out in the bulk or solution, which is called bulk (melt) polycondensation and solution polycondensation, respectively, and the polycondensation at the interface of two phases is called interfacial polycondensation.

Most of the monomers, solvents, initiators, catalysts, etc. used in the polymerization reaction are flammable and explosive substances, which are easily caused by fire if they are not used or stored properly. For example, the monomer ethylene of polyethylene is a combustible gas, the solvent benzene in the production of butadiene rubber is a flammable liquid, and the initiator sodium metal is a flammable dangerous goods when wet.

Many polymerization reactions are carried out under high-pressure conditions, and the monomers are prone to leakage during compression or in high-pressure systems, and fires and fires occur. For example, ethylene is polymerized at a pressure of 130 300 MPa to form polyethylene.