Polymethyl methacrylate copolymers

K. Kircher and R. Pieper, Polyurethane-Polymethyl methacrylate Copolymers, Kunststoffe 68(3), 141 (1978). SINs of PU and PMMA are described. Moldings were prepared. Swellability flexural strength, impact strength, and surface hardness were determined. 

After brief discussion of the state-of-the-art of modern Py-GC/MS, some most recent applications for stixictural and compositional chai acterization of polymeric materials are described in detail. These include microstixictural studies on sequence distributions of copolymers, stereoregularity and end group chai acterization for various vinyl-type polymers such as polystyrene and polymethyl methacrylate by use of conventional analytical pyrolysis. 

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.

This molecule is a copolymer with polymethyl methacrylate (PMMA) in acrylic latex paints, where the hydrophobic PMMA is surrounded by hydrophilic polyvinyl acetate molecules. Such a suspension of a hydrophobic polymer wrapped in a hydrophilic polymer is called a latex. 

Polymethyl methacrylate (PMMA) octylacrylamide/acrylates/butyl-aminoethyl methacrylate copolymer Plexiglas... 

One such reported example is the synthesis of polypropylene-6-polymethyl-methacrylate (PP-6-PMMA) copolymers utilizing metallocene catalysis and the borane chemistry. In the initial step, PP with chain-end olefinic unsaturations was prepared using metallocene catalysts such as Et(Ind)2ZrCl2/MAO. The unsaturation sites were then hydroborated by 9-borabicyclo[3.3.1]nonane (9-BBN) to produce borane-terminated PP (43) (Fig. 30), which was selectively oxidized and interconverted to a... 

Another useful, and quite sensitive, test is the initiation of polymerisation (c/ p. 320). Polymerisation can be initiated, in suitable substrates, by cations and anions as well as by radicals, but the effect of these several species can be differentiated by using a 50/50 mixture of phenylethene (styrene), PhCH=CH2, and methyl 2-methyl-propenoate (methyl methacrylate), CH2=C(Me)C02Me, as substrate cationic initiators are found to produce polystyrene only, anions polymethyl methacrylate only, while radicals produce a copolymer containing equal amounts of the two monomers. 

Another differential reaction is copolymerization. An equi-molar mixture of styrene and methyl methacrylate gives copolymers of different composition depending on the initiator. The radical chains started by benzoyl peroxide are 51 % polystyrene, the cationic chains from stannic chloride or boron trifluoride etherate are 100% polystyrene, and the anionic chains from sodium or potassium are more than 99 % polymethyl methacrylate.444 The radicals attack either monomer indiscriminately, the carbanions prefer methyl methacrylate and the carbonium ions prefer styrene. As can be seen from the data of Table XIV, the reactivity of a radical varies considerably with its structure, and it is worth considering whether this variability would be enough to make a radical derived from sodium or potassium give 99 % polymethyl methacrylate.446 If so, the alkali metal intitiated polymerization would not need to be a carbanionic chain reaction. However, the polymer initiated by triphenylmethyl sodium is also about 99% polymethyl methacrylate, whereas tert-butyl peroxide and >-chlorobenzoyl peroxide give 49 to 51 % styrene in the initial polymer.445... 

Radical copolymerization of diaryl nitrones, such as a-(2-hydroxyphenyl)-A-(2,6-dimethylphenyl) nitrone (HDN), a-(2-hydroxy-4-methacryloyloxyphenyl)-N -(2,6-dimethylphenyl) nitrone (HMDN), and a-(2-hydroxy-4-methacryloyloxy-phenyl)-A-phenylnitrone (HMPN) (Fig. 2.30), with methyl methacrylate leads to copolymers in good yields with considerable quantities of hydroxy substituted diaryl nitrone pendants. The presence of photoactive nitrone pendants in these copolymers allows one to control photochemically the refractive index of polymethyl methacrylate films (468, 700, 701). 

That is not to say that degradation in the presence of cavitation is thermal in origin as work by Melville has shown. Melville carried out both ultrasonic and thermal degradation of two samples of copolymer of polymethyl methacrylate and acrylonitrile, (molar ratio of methacrylate to acrylonitrile 411 1 and 40 1) and observed that whereas the latter copolymer had the faster thermal degradation rate, in the presence of ultrasound both copolymers showed practically the same rate of degradation. Further, a sample of polymethyl methacrylate had the same ultrasonic degradation rate as both of the copolymers (Fig. 5.20). 

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... 

G.E. Me Kee, M. Welz, A. Deckers, D. Wagner, P.O. Damm, and H.-J. Oslowski, Use of mixtures of polymethyl methacrylate and styrene-acrylonitrile copolymers for the production of laser-inscribed moldings, US Patent 6020106, assigned to BASF Aktiengesellschaft (Ludwigshafen, DE), February 1, 2000. 

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. 

In contrast the polymerization of vinyl acetate in the presence of polymethyl methacrylate gives after selective precipitation appreciable amounts of pure graft copolymer, independently of the nature of the initiator moreover the degree of grafting, evaluated by infrared spectrometry, is about equally important. Similar results were obtained in the system vinyl acetate-polyethyl a-chloroacryl ate. 

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). 

In the polymer impregnated gels, some porosity typically remains. Although some copolymers of methyl methacrylate, butadiene and styrene have been used to impregnate silica, the best known system is still silica impregnated with polymethyl methacrylate (PMMA)150-153. While this type of hybrid was important at first, it has been surpassed by other methods of hybrid synthesis that are simpler, with fewer steps and shorter times. 

A1(TPP)CH3 Methyl methacrylate (monomer) Polymethyl methacrylate Solvent benzene, CH2C12 Xlrr > 420 nm 100% conversion can be achieved in the presence of butyl methacrylate a copolymer is formed [115]... 

Chain polymerization (addition reactions) polyoxymethylene, polymethyl methacrylate (PMMA), acrylic polymers, polystyrene and styrene copolymers, water-soluble polyamide... 

Zilkha, Neta, and Frankel (105) polymerized acrylonitrile and methyl methacrylate with sodium-benzophenone ketyl. They found that polymethyl methacrylate anion initiated acrylonitrile With a mixture of styrene and acrylonitrile, no copolymer was formed. 

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... 

Literature continues to be rather extensive on this subject since the 1930s. A summarization is provided in this section. Products fabricated include sheets, films, rods and tubes, and embedment. Acrylic castings usually consist of polymethyl methacrylate (PMMA) or copolymers of this ester as the major component with small amounts of other monomers to modify the properties (Chapter 2). Adding acrylates or higher methacrylates lowers the heat deflection temperature and hardness and improves thermoformability and solvent cementing capability, with some loss in resistance to weathering. Dimethacrylates or other crosslinking monomers increase the resistance to solvents and moisture. 

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. 

Alkyl a-acetoxyacrylate intermediates were prepared by condensing pyruvate derivatives with acetic anhydride and then free radically converting them into the corresponding homo- or copolymers. All copolymers had thermal properties that were superior to that of polymethyl methacrylate. In addition poly(ethyl a-acetoxy-acrylate) homopolymers were injection moldable at 250°C. 

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