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MMA is a raw material for the manufacture of other methacrylates. These derivatives include ethyl methacrylate (EMA), butyl methacrylate (BMA) and 2-ethyl hexyl methacrylate (2-EHMA). Methacrylic acid (MAA) is used as a chemical intermediate as well as in the manufacture of coating polymers, construction chemicals and textile applications.
Two broad classes of monomers are susceptible to anionic polymerization. [3] Vinyl monomers have the formula CH 2 =CHR, the most important are styrene (R = C 6 H 5), butadiene (R = CH=CH 2), and isoprene (R = C(Me)=CH 2). A second major class of monomers are acrylate esters, such as acrylonitrile, methacrylate, cyanoacrylate, and acrolein.
Methacrylic acid, abbreviated MAA, is an organic compound with the formula CH 2 =C(CH 3)CO 2 H. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents.
The degree of polymerization, or DP, is the number of monomeric units in a macromolecule or polymer or oligomer molecule. [1] [2] [3]For a homopolymer, there is only one type of monomeric unit and the number-average degree of polymerization is given by ¯ ¯ = ¯, where ¯ is the number-average molecular weight and is the molecular weight of the monomer unit.
It is applied to alkylated methacrylate monomers and the initiator is a silyl ketene acetal. New monomer adds to the initiator and to the active growing chain in a Michael reaction. With each addition of a monomer group the trimethylsilyl group is transferred to the end of the chain.
The mass-average molecular mass, M w, is also related to the fractional monomer conversion, p, in step-growth polymerization (for the simplest case of linear polymers formed from two monomers in equimolar quantities) as per Carothers' equation: ¯ = + ¯ = (+), where M o is the molecular mass of the repeating unit.
One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. [33] The influence of the weight-average molecular weight on the melt viscosity depends on whether the polymer is above or below the onset of entanglements.
M n is the number average molecular weight, M w is the weight average molecular weight, M o is the molecular weight of the repeating monomer unit, Đ is the dispersity index. (formerly known as polydispersity index, symbol PDI) The last equation shows that the maximum value of the Đ is 2, which occurs at a monomer conversion of 100% (or p = 1 ...