The stereoregular polymerization of methyl methacrylate by Grignard reagents as affected by various alkyl groups, polymerization temperatures, and organic additives has been studied. These three factors were found to be effective in controlling the stereoregularity of PMMA. It has been confirmed that bands sensitive to stereoregularity at 757 and 749 cm.−1 correspond to isotactic and syndiotactic segments, respectively. Isotaxy and syndiotaxy were determined by the infrared method. Proton magnetic resonance spectra were found to be useful in analyzing the stereoregularity of PMMA and in estimating the amounts of stereoregular components in the polymer chains. Three elementary stereoregular units were proposed: isotactic, syndiotactic, and disyndiotactic. The kinetics of the polymerization reactions were studied in the cases of n‐butyl and isobutyl magnesium bromide. The rates of polymerization were found to be proportional to monomer concentration and to the square of the initiator concentration and molecular weight was proportional to monomer concentration and inversely proportional to initiator concentration. The rate of polymerization is maximum at a certain temperature. Branched‐alkyl Grignard reagents were found to produce isotactic polymer. Straight‐chain, alkyl‐type Grignard reagents, with the exceptions of n‐octyl‐ and n‐hexylmagnesium bromide, produce usually stereoblock polymer. Phenylmagnesium bromide (above 0°C.) and cyclohexylmagnesium bromide produce isotactic polymer. Low‐temperature, free‐radical polymerization results in almost wholly syndiotactic polymer. Ordinary free‐radical polymer has a stereoblock strucutre composed of syndiotactic and disynodiotactic units with smaller amounts of isotactic material. The addition of dioxane, pyridine, diphenylamine, or diethylamine promotes polymerization. Use of the latter two amines results in isotactic polymer.

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Motional Narrowing of Some Stereoregular Polymethyl MethacrylatesRecent studies of stereoregular polymerization of methyl-methacrylate have revealed that the stereoregularity of this polymer from the isotactic to the syndiotactic, can be controlled by selecting suitable conditions of po1ymerization.'s2 It is interesting to note how the stereoregularity affects the physical properties of this polymer.

Although various Si-containing resists for electron beam (EB) or Xray lithography have been reported (i), only a few positive resists have been reported so far (2).The reported positive resists consist of olefinsulfone series of polymers.However, these materials are generally liable to degrade by heating and their process conditions must be precisely controlled.Si-containing ~-chloroacrylate polymers are expected to be positive acting resists which are thermally stable.This communication reports the first example of sensitive Si-containing positive resists consisting of ~-chloroacrylate polymers.Our aim was to develop practical Si-containing positive resists by introducing a Si atom into the ester side chain of EBR-9 series of positive resists (3).Since large ester side chains make it possible for polymers to be cross-linked by ionizing radiation, the trimethylsilylmethyl group has been selected as the Si-containing ester side chain. This is because it is the simplest and a stable Si-containing ester side chain which can be easily synthesized.In this case, its Si content is as high as 14.5 wt % (calculated value), indicating that the polymer is likely to have a high resistance to 02 reactive ion etching (RIE).So, we have investigated poly(trimethylsilylmethyl a-chloroacrylate) SER-2 as a Si-containing positive electron resist for doublelayer processing technology.SER-2 monomer was synthesized from methyl ~-chloroacrylate by an ester interchange reaction with trimethylsilylmethyl alcohol. The polymer was synthesized by conventional radical polymerization.Its M w