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Polymers for Coatings for Plastics
Published in Rose A. Ryntz, Philip V. Yaneff, Coatings Of Polymers And Plastics, 2003
When more than one building block (monomer) is used in polymerization, a copolymer is the product. Copolymerization allows the polymer to be designed for specific physical or application properties. This is like blending ingredients in a formulation and fine tuning the product for optimum performance. As an example, methyl methacrylate is a monomer used in acrylic polymers and provides high hardness. Butyl acrylate is monomer that can be copolymerized with methyl methacrylate. Poly butyl acrylate gives a very soft and flexible polymer. By copolymerizing varying proportions of methyl methacrylate and butyl acrylate, the desired degree of hardness and flexibility can be dialed into the copolymer. This is more effective than blending a polymer of methyl methacrylate and one of butyl acrylate, because the two polymers may not be compatible with each other and may not provide a homogeneous film. In an alkyd resin, a “hard” component is phthalic anhydride. A soft, flexible component is one of the fatty acids used in making the alkyd resin. The amounts of phthalic anhydride and fatty acids can be varied to tune in the desired hardness properties of the coating. The same concept can be used for other properties of the coating, by controlling the amounts and type of the comonomers used in the polymerization. Obviously, the comonomers must react with each other in whatever process is being utilized. Figure 3 shows the chemical structure of the four building blocks previously mentioned. The methyl methacrylate and phthalic units are compact structures leading to hardness and less polymer chain mobility, while the butyl acrylate and fatty acid have longer linear segments that will facilitate more segmental movement in a copolymer and, therefore, provide softer, more flexible behavior.
Water structure of poly(2-methoxyethyl acrylate) observed by nuclear magnetic resonance spectroscopy
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Akira Mochizuki, Yuko Miwa, Chie Yahata, Dai Ono, Yoshinobu Oda, Tsubasa Kawaguchi
PMEA and poly(butyl acrylate) (PBA) (used as the control) were prepared by radical polymerization of the monomers (Tokyo Kasei, Tokyo, Japan) using 2, 2′-azobis-isobutyronitrile [9]. The number average molecular weight (Mn) and Mw/Mn of PMEA and PBA were 18 000 and 4.2, and 40 000 and 2.8, respectively, where Mw is the weight average molecular weight.
The interaction of carbon-centered radicals with copper(I) and copper(II) complexes*
Published in Journal of Coordination Chemistry, 2018
Thomas G. Ribelli, Krzysztof Matyjaszewski, Rinaldo Poli
Direct evidence was obtained later by EPR spectroscopy on the basis of a time-resolved single-pulse pulsed laser polymerization (SP-PLP) experiment [104]. Primary radicals were photogenerated by the laser pulse from α-methyl-4-(methylmercapto)-α-morpholinopropiophenone and allowed to initiate the polymerization of n-butyl acrylate (BA) to generate poly(butyl acrylate) radicals chains (PBA•), see Scheme 7. The rate of disappearance of these radicals was then measured by EPR spectroscopy in the absence and presence of L/CuI at –40 °C, a temperature chosen to avoid the occurrence of back-biting, which would produce less reactive mid-chain tertiary radicals. In the absence of L/CuI, the PBA• radicals disappeared by the standard bimolecular radical termination. In the presence of L/CuI complexes, on the other hand, a faster rate of disappearance obeying a first-order dependence in radicals and first-order in [CuI] generated a new distinct EPR signal attributed to the [L/CuII−RPBA] transient, which accumulated as a relatively stable species at –40 °C. The rate constant of the addition process could be determined as (3.0 ± 0.8) × 105, and (9 ± 3) × 103 M−1 s−1 for L = TPMA and N,N,N’,N”,N”-pentamethyldiethylenetriamine, while for L = N,N,N’,N”,N’’’,N’’’-hexamethyltriethylenetetraamine this constant was too low for an accurate determination by this technique. These adducts decomposed upon warming to 0 °C. For comparison, the rate constants for the corresponding ATRP deactivations (Br atom transfers from [L/CuII−Br] where measured as (0.9 ± 0.2) × 106, and (6 ± 2) × 106 and (2.0 ± 0.5) × 106 M−1 s−1 in similar SP-PLP experiments conducted in the presence of copper(II) complexes with the same three ligands. The comparison shows that, for these complexes and polymer chain, the OMRP deactivation (Scheme 2) is slower than the ATRP deactivation (Scheme 1) and more strongly influenced by the ligand nature. The EPR signature of these species is different than, but shows similar parameters to that of [L/CuII−Br]. This transient decomposed at higher temperature, to regenerate the L/CuI precursor plus terminated macromolecules. It is to be noted that all these CRT investigations were conducted in MeCN as solvent. As already shown above, EPR spectroscopic evidence for the generation of a [L/CuII−R] species was also obtained in an electrochemical investigation conducted on a molecular model [102].