NationMaster - Encyclopedia: Copolymerization

In chemistry, copolymerization is the process of using more than one monomer in the production of a polymer, resulting in a product with properties different to the homopolymer of either monomer. The resulting product may be a random copolymer, an alternating copolymer, or a block copolymer. In the copolymerization between two monomers, M₁ and M₂, the following reactions may occur: Chemistry (derived from the Arabic word kimia, alchemy, where al is Arabic for the) is the science that deals with the properties of organic and inorganic substances and their interactions with other organic and inorganic substances. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... Polymer is a generic term used to describe a very long molecule consisting of structural units and repeating units connected by covalent chemical bonds. ... A homopolymer is a polymer which is formed from only one type of monomer. ...

~~M₁^* + M₁ --> ~~M₁M₁^* (rate constant = k₁₁)

~~M₁^* + M₂ --> ~~M₁M₂^* (rate constant = k₁₂)

~~M₂^* + M₁ --> ~~M₂M₁^* (rate constant = k₂₁)

~~M₂^* + M₂ --> ~~M₂M₂^* (rate constant = k₂₂)

1 Copolymerization Equation
- 1.1 Effect of Reactivity Ratios
2 Examples
3 See also

In chemical kinetics a reaction rate constant quantifies the speed of a chemical reaction. ...

Copolymerization Equation

The Mayo-Lewis equation (also called the copolymerization equation) gives the molar ratios of the two monomers in the resulting copolymer as:

$frac {dleft [M_1 right ]}{dleft [M_2right ]}=frac{left [M_1right ]left (r_1left[M_1right ]+left [M_2right ]right)}{left [M_2right ]left (left [M_1right ]+r_2left [M_2right ]right)}$

where r₁ and r₂ are the reactivity ratios of the individual monomers and r₁ = k₁₁/k₁₂ & r₂ = k₂₂/k₂₁, i.e. r = the rate of reaction with another monomer of itself / the rate of reaction with a different monomer. r is also called the copolymerization parameter.

k₁₁ and k₂₂ are the rate constants for the homopolymerization of the two monomers. k₁₂ and k₂₁ are the rate constants for the reaction between the two different monomers.

In another form:

$F_1=1-F_2=frac{r_1 f_1^2+f_1 f_2}{r_1 f_1^2+2f_1 f_2+r_2f_2^2}$

where F₁, F₂ are the mole fractions of monomers M₁, M₂ in copolymer:

F₁=1-F₂=d[M₁]/(d[M₁]+d[M₂])

and f₁, f₂ are the mole fractions of monomers M₁, M₂ in the feed:

f₁=1-f₂=M₁/(M₁+M₂)

When the copolymer composition has the same composition as the feed, this composition is called the azeotrope.

Effect of Reactivity Ratios

Homopolymer: favored when r = ∞

-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A- (r₁ = ∞)

-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B-B- (r₂ = ∞)

Random copolymer (or statistical copolymer): favored when r₁, r₂ close to 1.

-A-A-B-B-A-A-A-B-A-A-B-B-A-B-A-A-A-B-A-A-A-B-B-

Alternating copolymer: favored when r₁, r₂ close to zero.

-A-B-A-B-A-B-A-B-A-B-A-B-A-B-, or -(-A-B-)_n-

Block copolymer: favored when r₁ >1 r₂ >1

-A-A-A-A-A-A-A-B-B_A+B+B+A_R+O+C+K+S-B-B-B-B-B-A-A-A-A-A-A-A-B-B-...

A homopolymer is a polymer which is formed from only one type of monomer. ... Alternating copolymers: Have properities intermediate to those of the corressponding homopolymers A and B ... A heteropolymer, also called a copolymer, is a polymer formed when two different types of monomer are linked in the same polymer chain. ...

Examples

acrylonitrile butadiene styrene (ABS) plastic, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), P(VDF-TrFE). Monomers in ABS polymer Acrylonitrile butadiene styrene, or ABS, (chemical formula ) is a common thermoplastic used to make light, rigid, molded products such as pipes, golf club heads (used for its good shock absorbance), automotive body parts, enclosures and toys including LEGO bricks. ... Plastic is a term that covers a range of synthetic or semisynthetic polymerization products. ...

Process for producing graft-modified .alpha.-olefin copolymer - Patent 5037890 (9671 words)
	Copolymerization of ethylene/propylene/divinylbenzene was conducted in the same conditions and methods as is Example A9 except that 4.49 mmole of triethylaluminium and 2.26 mmole of titanium tetrachloride (molar ratio of Al/Ti=2) were used as a catalyst, and 10 ml of divinylbenzene and 1,500 ml of hydrogen were used with a copolymerization time of 5 hours.
	Copolymerization was conducted in the same manner and condition as in the step (a) of Example A1 except that 200 mg of titanium trichloride and 600 ml of hydrogen were used to obtain 198 g of a propylene/divinylbenzene copolymer (catalyst activity: 990 g copolymer/g solid catalyst).
	Copolymerization of ethylene/propylene/divinylbenzene was conducted in the same manner and condition as in Example A9 except that 4.49 mmole of triethylaluminium and 2.26 mmole of titanium tetrachloride (molar ratio Al/Ti=2) were used as a catalyst, 5.0 ml of divinylbenzene and 1,000 ml of hydrogen were used and copolymerization time was set as 5 hours.

Copolymerization - Wikipedia, the free encyclopedia (199 words)
	In chemistry, copolymerization is the process of using more than one monomer in the production of a polymer, resulting in a product with properties different to the homopolymer of either monomer.
	The resulting product may be a random copolymer, an alternating copolymer, or a block copolymer.
	The Mayo-Lewis equation (also called the copolymerization equation) gives the molar ratios of the two monomers in the resulting copolymer as:

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Contents

Copolymerization Equation GA_googleFillSlot("encyclopedia_square");

Effect of Reactivity Ratios

Examples

See also

Copolymerization Equation