Block polymethyl methacrylate

The main experimental techniques used to study the failure processes at the scale of a chain have involved the use of deuterated polymers, particularly copolymers, at the interface and the measurement of the amounts of the deuterated copolymers at each of the fracture surfaces. The presence and quantity of the deuterated copolymer has typically been measured using forward recoil ion scattering (FRES) or secondary ion mass spectroscopy (SIMS). The technique was originally used in a study of the effects of placing polystyrene-polymethyl methacrylate (PS-PMMA) block copolymers of total molecular weight of 200,000 Da at an interface between polyphenylene ether (PPE or PPO) and PMMA copolymers [1]. The PS block is miscible in the PPE. The use of copolymers where just the PS block was deuterated and copolymers where just the PMMA block was deuterated showed that, when the interface was fractured, the copolymer molecules all broke close to their junction points The basic idea of this technique is shown in Fig, I. 

Scheme 1 Schematic structure of graft block copolymer [51] TTTm = polymethyl methacrylate segment w AA = po-lydimethylsiloxane segment.

Formation of block polymers is not limited to hydrocarbon monomers only. For example, living polystyrene initiates polymerization of methyl methacrylate and a block polymer of polystyrene and of polymethyl methacrylate results.34 However, methyl methacrylate represents a class of monomers which may be named a suicide monomer. Its polymerization can be initiated by carbanions or by an electron transfer process, the propagation reaction is rapid but eventually termination takes place. Presumably, the reactive carbanion interacts with the methyl group of the ester according to the following reaction... 

Keqiang [43] has successfully produced block copolymers, based upon cellulose, while Henglein has been able to produce both graft and block copolymers using polystyrene and polymethyl methacrylate. Price [68] has shovm that the irradiation of mixtures of polystyrene and poly(cis-butadiene) and separately polystyrene and... 

Berlin [69] had shown that for the block copolymerisation of polymethyl methacrylate with acrylonitrile, the time required to produce a given amount of polyacrylonitrile in the block decreased with increasing intensity. 

Fig. 24. Composition during the mastication of initially (a) 24% methyl methacrylate in polystyrene and (b) 38% styrene in polymethyl methacrylate. Curves a, b, and c Free polystyrene, block polymer, and free polymethyl methacrylate, respectively. Curves d, b and c ...

Free polymethyl methacrylate, block polymer and free polystyrene, respectively. (--) %... 

Block and graft copolymers were prepared by Akutin, Parlashke-vich, Kogan, Kalinina, and Menes (128) by the use of ultrasonics on solutions of fluorine containing polymers or polysiloxanes on one hand and polymethyl methacrylate, polyvinyl chloride, ethylcellulose on the other. 

This tertiary amine group terminated polymer can undergo transfer in the presence of a second monomer (25, 26), e.g. with acrylonitrile or methyl acrylate which show an exceptionally high transfer constant with such groups (see Table 2). By this method acrylonitrile blocks are bounded to polymethyl methacrylate sequences the overall composition of these block copolymers may be represented by... 

By ultrasonic irradiation of a solution of polymethyl methacrylate in vinyl acetate or in styrene, no appreciable amount of block copolymer could be found 154). Henglein succeeded with addition of acrylonitrile to polyacrylamide dissolved in water 100). Although acrylonitrile itself... 

The ultrasonic irradiation of a mixture of polymers also produces block copolymers, when chain fragments combine with each other and cross termination is predominant in the case of a benzene solution of polymethyl methacrylate and polystyrene, Henglein showed that 33% of the radicals produced combine (101). 

The mechanical degradation and production of macroradicals can also be performed by mastication of polymers brought into a rubbery state by admixture with monomer several monomer-polymer systems were examined (10, 11). This technique was for instance studied for the cold mastication of natural rubber or butadiene copolymers in the presence of a vinyl monomer (13, 31, 52). The polymerization of methyl methacrylate or styrene during the mastication of natural rubber has yielded copolymers which remain soluble up to complete polymerization vinyl acetate, which could not produce graft copolymers by the chain transfer technique, failed also in this mastication procedure. Block and graft copolymers were also prepared by cross-addition of the macroradicals generated by the cold milling and mastication of mixtures of various elastomers and polymers, such as natural rubber/polymethyl methacrylate (74), natural rubber/butadiene-styrene rubbers (76) and even phenol-formaldehyde resin/nitrile rubber (125). 

The case of "living polystyrene and methyl methacrylate is somewhat similar. It was shown, as should be expected, that "living polymethyl methacrylate does not initiate styrene polymerization (70), i. e. methyl-methacrylate is a terminator for the latter polymerization, although its addition to living poly-styrene initiates its polymerization. Hence, one may produce a block polymer by adding methyl methacrylate to "living polystyrene but not vice-versa (9,10). 

As mentioned above, the ability to have living polymerizations offered the potential to make block copolymers. In the preparation of a block copolymer the sequence of addition can be important to ensure that the second monomer is capable of adding to the living end. An example is the formation of a polystyrene—polymethyl methacrylate block copolymer.38 In this case polystyrene is polymerized first, followed by addition of the methyl methacrylate. The block copolymer could not be formed if methyl methacrylate were polymerized first, as styrene will not add... 

A method for preparing isolatable and re-activatable polymethyl methacrylate using the chain transfer agent bis(ethoxythiocarbonyl)disulfane with 2,2 -azobis(isobutyr-onitrile) is described. Reactivation of this macroinitiator with 2,2 -azobisisobutyr-onitrile was then used to prepare block copolymers. 

All rubbers, glasses, and plastics are polymers. You are probably familiar with natural polymers like cellulose (the building block of plant fibers) and synthetic polymers like polyethylene (plastic milk cartons), polyisoprene (automobile tires), polyethylene terephthalate (soft drink bottles), polymethyl methacrylate (Plexiglas ), polyvinylidene chloride (transparent plastic wrap), polytetrafluoroethylene (Teflon ), and various polyesters (fabrics). Polyvinyl chloride, the polymer shown earlier, is used to make rigid pipes, house siding, and protective coverings for automobile seals and dashboards, among many other applications. 

Samples can be in block, flake, fiber or powder form. Sample form is the second most important parameter affecting TG curves. The sample form effect on a TG curve is demonstrated in Figure 10.23, which shows the TG curves of different forms of polymethyl methacrylate... 

Tphe surface activity of block copolymers containing dimethylsiloxane units as one component has received considerable attention. Silicone-poly ether block copolymers (1,2,3) have found commercial application, especially as surfactants in polyurethane foam manufacture. Silicone-polycarbonate (4, 5), -polystyrene (6, 7), -polyamide (8), -polymethyl methacrylate (9), and -polyphenylene ether (10) block copolymers all have surface-modifying effects, especially as additives in other polymeric systems. The behavior of several dimethylsiloxane-bisphenol A carbonate block copolymers spread at the air—water interface was described in a previous report from this laboratory (11). Noll et al. (12) have described the characteristics of spread films of some polyether—siloxane block co-... 

Methyl methacrylate (MMA) and sodium styrene sulfonate (SSNa) are water-soluble. These polymers behave like a low MW surfactant as they form micelles in aqueous solution in which the hydrophobic part is directed towards the centre and the hydrophilic part is situated on the periphery of the micelle. Owing to such features, amphiphilic block copolymers have wide-ranging applications in drugs, pharmaceuticals, coatings, cosmetics and paints. They also exhibit very high antibacterial activities. Oikonomou and co-workers used ATRP to prepare amphiphilic block copolymers, consisting of polymethyl methacrylate (PMMA) and poly (sodium styrene sulfonate) (PSSNa) blocks [18]. The synthesis methods are described below. 

Synthesis of the I-poly(sodium styrene sulfonate)- -polymethyl methacrylate (Pla) block copolymer... 

Particle diameter versus annealing time at 180°C for (a) 70/30 polystyrene/polymethyl methacrylate (PS/PMMA) bend without addition of a copolymer and (b) 70/30 PS/PMMA blend with 5% PS-b-PMMA copolymer. (Reproduced from Macosko, C. W., Guegan, R, Khandpur, A. K., Nakayama, A., Marechal, P., and Inoue, T. 19%. Compatibitizers for melt blending Premade block copolymers. Macromolecules 29 5590-5598 with permission from American Chemical Society.)... 

Asemblon, Inc. (Redmond, Washington). 11-Mercaptoundecanoic acid (MUDA) with 97% pinity, 16-mercaptohexadeconic acid (MHA) with 90% purity and 1-octadecanethiol (ODT) with 98% purity were purchased from Aldrich (St. Louis, Missouri). Polystyrene (PS) standard with 18,100 Da poly (acrylic acid) (PAA) with 2000 Da polymethyl methacrylate (PMMA) standard with 15,000 Da M , PS-PAA block copolymers and the solvents including acetonitrile, acetone, anhydrous ethanol, toluene, and N,N-dimethylformamide (DMF) were purchased from Aldrich. 

Cellulose acetate butyrate lonomer resin Polyethylene, chlorosulfonated Polyethylene elastomer, chlorinated Polyvinyl chloride Styrene-ethylene/butylene-styrene block copolymer Tetrafluoroethylene/propylene copolymer tubing, chemicals Polymethyl methacrylate tubing, flexible... 

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