New free radical catalysts for the polymerization of methyl methacrylate and other acrylic monomers have been reported. They comprise mixtures or salts of N,N‐dialkyl aryl amines and o‐benzoic sulfimide (saccharin). A p‐substituent on N,N‐dimethylaniline or N,N‐diethylaniline had a significant influence upon polymerization. Electron‐donating groups such as methyl or methoxy increased the total yield of the polymer, while electron‐withdrawing groups, namely, chlorine, bromine, or aldehyde, reduced the yield of the polymer. When electron‐withdrawing groups, namely, nitro, nitroso, or phenylazo, were present in the para position of dimethylaniline, no polymer was obtained. Presence of a methyl group in the meta position in dimethylaniline enhanced the yield of the polymer. However, when a methyl group was present in the ortho position, the yield of the polymer was significantly reduced, probably due to a steric factor. Binary mixtures containing equimolar proportions of saccharin and the amine were better initiators for methyl methacrylate polymerization than the corresponding salts of saccharin and amine. A number of organic acids in admixture with dimethylaniline also polymerized methyl methacrylate. The stronger the acid, the greater was the yield of the polymer. However, the yields were considerably lower than in case of dimethaniline‐saccharin mixture as catalyst.

No abstract

No abstract

Challenging traditional historiography that claims Lyndon B. Johnson's foreign policy was his political weakness, this article aligns itself with recent, more positive assessments of his record 'beyond Vietnam'. President Johnson contributed to the avoidance of a lasting split in the Atlantic alliance despite General de Gaulle's anti-Americanism, the unpopularity of the US engagement in Vietnam, and increasing US calls for 'burden-sharing'. He was able to do this by recognising his own and his country's limitations in external affairs, by relying on the judgement of key advisers, by adopting a calm approach in contrast to de Gaulle's inflammatory behaviour, and by supporting progress toward détente and Ostpolitik. Thus, although transatlantic relations faced major tensions and serious realignment during the Johnson years, they remained relatively stable.

No abstract