Poly -methyl methacrylate copolymer degradation

O Driscoll reports that several polymer-monomer combinations were used in the controlled preparation of homo- and block polymers by ultrasonic radiation(108). Similarly, Fujiwara reports the preparation of poly(styrene-b-methyl methacrylate) by ultrasonic degradation of polystyrene(109). The utility of ultrasonic irradiation is limited since yields are usually low, and the block copolymer is often contaminated with relatively large amounts of the homopolymers. 

THE PREPARATION AND PHOTOOXIDATIVE DEGRADATION OF POLYESTERURETHANE-POLY (METHYL METHACRYLATE) TRIBLOCK COPOLYMERS... 

If a mechanical degradation of a solution of two polymers is carried out by high speed stirring, the formation of a block copolymer is not probable as the scission of polymer molecules at low concentration is not caused mainly by intermolecular interaction, such as by collision of molecules and through entanglements, but by displacements due to hydrodynamic forces in velocity gradients. Nakamo and Minoura (98) did obtain reaction by stirring a benzene solution of polyethylene oxide and poly(methyl methacrylate). 

The dithiocarbamates have the pentacoordinate binuclear structure (44). The diamyl- and diethyl-dithiocarbamate complexes have been found to inhibit the hardening of asphalt, but the effect appears too weak to be useful.127 The latter complex is an effective antioxidant for polyethylene,128 polypropylene,129 polystyrene,130 poly(methyl methacrylate)130 and an isoprene-styrene copolymer.131 The di-n-butyldithiocarbamate complex is important in the vulcanization and injection moulding of rubber,132 as a stabilizer against photolytic and thermal degradation. 

Poly(acrylates) and (alkyl acrylates). - Structured nanopore films of poly(styrene-block-methyl methacrylate) copolymers have been made with controlled spectral sensitivity, such that each block is sensitive to a specific degradation wavelength. In copolymers of 2,2,2-trifluoroethyl methacrylate with vinyl ethers, the photosensitivity is controlled by the vinyl ether units. Photodegradation occurs at the tertiary positions of the ether units followed by lactone formation and chain scission processes. Furthermore, the fluorinated side chains have been found to inhibit cyclization reactions. 

Block copolymers consisting of PPV and poly(methyl methacrylate) (PMMA) blocks, can be obtained by atom transfer radical polymerization. The thermal stability is slightly improved in comparison to neat PPV derivates by the introduction of PMMA blocks. The onset of thermal degradation starts around 200°C. 

Table 1.1 Reported techniques to selectively degrade one copolymer block. Poly(styrene) PS, poly (dimethylsiloxane) PDMS, poly(ethyleneoxide) PEO, poly(isoprene) PI. poly(lactic acid) PLA. poly(methyl methacrylate) PMMA, poly(vinylpyridine) PVP, 3-pentadecylphenol PDP...

More recently, another study was carried out on the thermal decomposition of homopolymers of ethyl methacrylate, n-butyl methacrylate, and 2-hydroxyethyl methacrylate as weU as then-copolymers [471]. The copolymers of hydroxyethyl methacrylate with ethyl methacrylate and butyl methacrylate were found to degrade by unzipping to yield the monomers similarly to poly(methyl methacrylate). In addition, there is competition between imzipping and cross-linking in binary copolymers of hydroxyethyl methacrylate with ethyl methacrylate and in n-butyl methacrylate. 

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