Hydroxyl-functionalized polymers

MALDI spectrum of a hydroxyl functional polymer prepared by GTP the level of the impurity is easily seen and the success of this reaction clearly observed. However, this is not a universally applicable technique. Perhaps the most topical living polymerisation at present is transition metal mediated radical polymerization. This typically gives a polymer with a tertiary halide terminal group. This group, as has nitroxide, has been found to be very labile in the mass spectrometer leading to fragmentation. 

Samarium. In 1996, Endo determined that, in the presence of Mg/Me SiCl, carbonyl compounds can be reductively dimerized by a catalytic quantity of Sml2 (Eq. 3.30) [51, 52]. Aliphatic and aromatic aldehydes and ketones can be coupled with this system. This catalytic process has recently been applied to the synthesis of hydroxyl-functionalized polymers [53]. 

Graft copolymers were prepared by both classical strategies, that is, from enzymatically obtained macromonomers by subsequent chemical polymerization and by enzymatic grafting from hydroxyl functional polymers. Kalra et al. studied the synthesis of PPDL graft copolymers from macromonomers, which were obtained by the enzymatic ROP of pentadecalactone (PDL) from hydroxyethyl methacrylate (HEMA) and polyethylene glycol) methacrylate (PEGMA) [40]. Subsequently graft copolymers were obtained by free radical polymerization of the macromonomers. A similar approach was published by Srivastava for the HEMA-initiated enzymatic ROP of CL and subsequent free radical polymerization [41]. 

Anionic Synthesis of Hydroxyl-Functionalized Polymers Using Protected, Functionalized Alkyllithium and Isoprenyllithium Initiators... 

Analogous functionalization reactions of PBDLi (Mn = 2500) with 1-butene oxide were investigated. By quantitative column chromatography, the yield of hydroxyl-functionalized polymer was determined to be 98%. NMR analysis by integration of the hydrogen on the carbon bonded to oxygen compared to the methyl groups from the initiator at <5 = 0.9 ppm indicated that the functionalized polymer was obtained in 97% yield. Thus, the results were similar to those obtained for PSLi functionalization. 

In order to improve the yield of hydroxyl-functionalized polymers, the effect of addition of THF was investigated. It is known that Lewis bases such as THF reduce or eliminate association of polymeric organolithium chain ends. If the formation of the polystyrene dimer is favored by association of PSLi chain ends, it was expected that the addition of Lewis base would minimize dimer formation. Upon the addition of THF ([THF]/[PSLi] > 15) to PSLi prior to addition of styrene... 

In principle, another general method for the preparation of hydroxyl-functionalized polymers is through the reaction of polymeric organolithium compounds with carbonyl compounds. The reaction of polymeric organolithium compounds with the simplest carbonyl compound, formaldehyde, has been reported. ... 

In the early days, although paint manufacturers flirted with acrylamide chemistry for automotive topcoats, their higher curing temperatures of 150 C and above precluded commercialisation in this end use. Carboxy functional acrylics have inferior weathering performance. Consequently, thermosetting acrylic topcoats are almost exclusively based on hydroxyl functional polymers. These are crosslinked with either alkylated melamine formaldehyde resins or as 2 component (2K) systems, with aliphatic isocyanate adducts. The 2 component systems are an extremely important class used mainly in automotive repair applications and warrant a chapter in their own right (see Chapter V on component isocyanate curing systems). 

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