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The change of tacticity of methacrylate blocks in the anionic block copolymerization of ethylene oxide with methyl methacrylate or rerr-butyl methacrylate as function of the number of monomeric units in the poly(ethy1ene oxide) (PEO) sequences formed in the first polymerization step, was studied. The fraction of the syndiotactic triads of the polymethacrylates was found to increase with the DP of the PEO precursor. When the plateau value was reached, the tacticity was similar to that of poly(methy1 methacrylate) initiated by alkali alkoxides when solvated with crown ethers. The variation of the tacticity was smaller with rerr-butyl methacrylate than with methyl methacrylate. The growth reaction of methacrylate monomers was found to follow Bernoullian statistics. It is assumed that the solvation of the counterions increases with increasing of the monomeric units in the starting poly(ethy1ene oxide) blocks.

The photo-induced radical polymerization of acrylamide has been investigated in combinations of two polymers containing carboxy groups. The kinetic parameters of this polymerization, measured with a calorimetric method, depend on the proportion of the two polymers in the system. In mixtures with the lowest glass transition temperature, the polymerization rates are the highest. These transition temperatures have been determined with a special fluorescence technique using crystal violet as probe. Presumably, the effects measured in the systems are based on the strong polar interactions between the carboxy groups of both polymers. ZUSAMMENFASSUNG:Die photoinduzierte radikalische Polymerisation von Acrylamid in Kombinationen von zwei Polymeren, die Carbonsauregruppen enthalten, wurde untersucht. Die kinetischen Parameter dieser Polymerisation, gemessen mit Hilfe einer kalorimetrischen Methode, hangen vom Mischungsverhaltnis der beiden Polymeren im System ab. In Gemischen mit der niedrigsten Glastibergangstemperatur ist die Polymerisationsgeschwindigkeit am hochsten. Diese Ubergangstemperaturen wurden mit Hilfe einer speziellen Fluoreszenztechnik unter Benutzung von Kristallviolett bestimmt. Die gemessenen Effekte werden wahrscheinlich durch die stark polaren Wechselwirkungen zwischen den Carboxygruppen der beiden Polymeren verursacht. SMBuHa CMS Experimental partMaterials a-Isopropoxydeoxybenzoin (BIPE) was synthesized using a known procedure4. Acrylamide (p, a.) (Fluka) and crystal violet (Merck) are pure commercial substances. The binders employed (CMS, M, = 550 g/mol; SMBuHa, M, = 100OOO g/mol) are also commercial substances (Buna AG/Filmfabrik Wolfen AG) and were used without further purification.