Trimethylsilyl methacrylate

The fact that trimethylsilyl methacrylate is a sluggish monomer under GTP conditions [45, 46] also bodes well for a dissociative mechanism. The excess silyl carboxy groups are silylating enolate chain ends Thus lowering the rate of polymerization and changing the nature of the carboxylate catalyst (Scheme 23c). 

The samarocene complexes SmMe(C5Me5)2(THF) and Smn(( 5Mc5)212 were employed as initiators for the synthesis of the well-defined block and triblock copolymers poly(trimethylsilyl methacrylate)-fc-PMMA, PTMSMA-fo-PMMA, PMMA-fo-PTMSMA, PTMSMA-fo-P BuA, PMMA-fo-P BuA, and PMMA-fo-P BuA-fo-PMMA [115]. When the procedure started with MMA polymerization, followed by the addition of TMSMA, block copolymers with low polydispersity and stoichiometric molecular weights in very good agreement with the experimental values were obtained. The reverse mode of add-... 

Copolymers of methacrylonitrile with 4-trimethylsilyloxy-a-methylstyrene, HFA-bearing a-methylstyrene, and trimethylsilyl methacrylate have been proposed as 157 nm positive resits [317]. 

Further, I propose to attempt the synthesis of DG-forming poly(benzyl meth-acrylate)- -poly(styrene)-fe-poly(lactic acid) orpoly(trimethylsilyl methacrylate)-l>-poly(styrene)- -poly(lactic acid) using HEBIB as initiator in the following order First, ATRP of styrene second, ATRP of the substituted methacrylate and finally, ROP of lactide. Selective and successive degradation of the methacrylate and lactide blocks would enable to separately address and replicate the two double-gyroid networks. 

Polymerization of trimethylsilyl methacrylate to alternatively form the isotactic, syndiotactic and atactic polymers has been described previously (22). The molecular weight and tacticity of these polymers could be determined after acidic workup of the polymerization reaction followed by isolation of the polymer and treatment with diazomethane to form poly(methyl methacrylate). The molecular weight and tacticity of these polymers are given in Table II. The values obtained represent dramatic differences in tacticity as a function of preparation method and thus provide a reasonable basis for the testing the effect of polymer microstructure on its subsequent behavior. 

Conditions for preparation of poly(trimethylsilyl methacrylate). All reactions were run in toluene for 24 hours using a monomerxatalyst ratio of 50 1. As determined by gel permeation chromatography in tetrahydrofuran versus poly(methyl methacrylate) standards. PDI = Mw/Mn. As determined by NMR spectroscopy. OBHT = -0-(2,6-di-t-butyl)-4-methylbenzene (butylated hydroxy toluene)... 

After some time, ethylene glycol dimethacrylate and dry methanol were added and distillation was begun. The addition of methanol deblocks the trimethylsilyl methacrylate and converts it into methacrylic acid. Eventually, l-methyl-2-pyrrolidinone is added. This forms a butyl methacrylate, methacrylic acid, and ethylene glycol dimethacrylate star. 

Controlled structure PMAA can be prepared by the deprotection of an appropriate precursor polymethacrylate which has itself been polymerized under living conditions. Both anionic polymerization and GTP have been used to prepare PMAA employing a variety of PMAA precursor monomers such as benzyl methacrylate (125), ter -butyl methacrylate (126), trimethylsilyl methacrylate (127) and 2-tetrahydropyranyl methacrylate (128,129). Removal of the protecting group yields the desired PMMA. 

It was not until the 1970s that the first block polyampholytes were reported (251,252). Anionic polymerization was used to prepare precursor AB diblock copolymers of 2-vinylpyridine lOZ with trimethylsilyl methacrylate (TMSMA). The TMSMA residues were subsequently hydrolyzed to poly(methacrylic acid) residues to yield the corresponding AB diblock polyampholytes. Anionic poljnner-ization has also been employed to prepare other block polyampholytes (253-258). GTP has also been successfully employed for the preparation of block polyampholytes. As with anionic polymerization, protected acid monomers must be employed since methacrylic acid (MAA) cannot be polymerized directly by this technique. A variety of protected monomers have been reported to be suitable as a means of introducing MAA residues, with 2-tetrahydropyranyl methacrylate being the most effective (Fig. 46). 

Typical procedure. Ethyl (E)-3-(trimethylsilyl) methacrylate 1867 [1388] To a stirred solution of oxalyl chloride (131 pL, 0.190 mg, 1.50 mmol) in dichloromethane (8.0 mL) at —78 °C was added dimethyl sulfoxide (121 pL, 0.133 mg, 1.70 mmol). After 10 min, a solution of (trimethylsilyl)methanol (104 mg, 1.00 mmol) in dichloromethane (2 mL) was added over 4 min, and, after 15 min, triethylamine (0.52 mL, 377 mg, 3.7 mmol) was added over 1 min. After 5 min at —78 °C, a solution of ethyl 2-(triphenylphosphoranylidene)propionate (690 mg, 1.9 mmol) in dichloromethane was added over 3 min. The reaction mixture was then allowed to warm to room temperature, diluted with diethyl ether (70 mL), and then washed with water (40 mL) and brine (40 mL). The organic phase was dried over magnesium sulfate and then concentrated under reduced pressure. Chromatography of the residue eluting with diethyl ether/petroleum ether, 3 97, afforded 101 mg (54%) of product 1867 as a colorless oil. 

Up to now the only way to get isotactic poly(acrylic acid) or poly(methacrylic acid) has been by hydrolysis of isotactic poly(acrylates) or poly(methacrylates) [476]. Direct routes to get isotactic polymers would be anionic and coordination polymerization. But these polymerizations are not practicable, because the acid function would destroy the initiator. Kargin et al. [477] prepared isotactic poly(acrylic acid) by reaction of isotactic poly(isopropylacrylate) in toluene as solvent with potassium hydroxide in propanol. Propanol and the formed isopropanal were removed after reflexing for 6 h by distillation. Complete hydrolysis was reached after 10 h. Aylward synthesized isotactic and syndiotactic poly(methacrylic acid) by quantitative hydrolysis of poly(trimethylsilyl methacrylate) [478]. 

Copolymerization of trimethylsilyl methacrylate and 3-oximino-2-butanone methacrylate yields copolymers (18) with improved sensitivity to deep UV light, while maintaining good resistance to oxygen plasma. 

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