PMMA/PnBA

Some two stage emulsion graft copolymer materials synthesized and characterized by DMS include) the series poly (methyl methacrylate)/poly(n-butyl acrylate) (PMMA/ PnBA) synthesized by Dickie (14) and the series poly(ethyl methacrylate)/poly(n-butyl acrylate) (PEMA/PnBA) synthesized by Sperling et al. (1) The present study will continue the development of the PEMA/PnBA damping materials by incorporating a common comonomer) ethyl acrylate (EA)) in both stages of the emulsion polymerization. 

Stenert, M., Doring, A., and Bandermann, F. 2004. Poly(methyl methacrylate)-block-polystyrene and polystyrene-block-poly( -butyl acrylate) as compatibihzers in PMMA/PNBA blends, e-Poly-mers 15,1-16. 

Figure 1. Rate oj leaching oj a UV stabilizer jrom PMMA and PNBA when those blends are immersed in water at 25°C...

Figure 2.54 The geometry of one of the substrates employed by Murray and Allara in their spacer experiments. PMMA = polymelhyl methacrylate spacer of thickness J, PNBA = monolayer of p-nitrobcnzoic acid. The mass thicknesses of the other layers are CaF, = 800 A. Al = 2500 A. Al = oxide c. 30 A, Ag = 200 A. From Murray and Allara (1982).

The temperature optimization for the RAFT polymerization of EAA revealed an optimum reaction temperature of 70 °C. Block copolymers with a poly(methyl acrylate) (PMA), a poly(n-butyl acrylate) (PnBA), a PMMA, or a poly(A,A-dimethyl aminoethyl methacrylate) (PDMAEMA) first block and a poly(l-ethoxyethyl acrylate) (PEEA) second block were successfully synthesized in an automated synthesizer. The synthesis robot was employed for the preparation of 16 block copolymers consisting of 25 units of the first block composed of PMA (exp. 1 ), PnBA (exp. 5-8), PMMA (exp. 9-13), and PDMAEMA (exp. 13-16) and a second block of PEEA consisting of 25, 50, 75, or 100 units, respectively. The first blocks were polymerized for 3 h and a sample from each reaction was withdrawn for SEC analysis. Subsequently, EAA was added and the reactions were continued for 12 h. The molar masses and PDI values of the obtained block copolymers are shown in Fig. 15. 

Fig. 15 Number average molar masses (Mn opc) and PDI values obtained for the first blocks and for the final copolymers of PMA, PnBA, PMMA, or PDMAEMA (25 units) with PEEA (25, 50, 75, and 100 units for 100% conversion). AH Mn pc values are calculated against PMMA standards. SEC eluent CHClsiNEtsii-PrOH. (Reprinted with permission from [87]. Copyright (2005) American Chemical Society)...

PE graft copolymers were synthesized from PE-OH by Inoue et al. using ATRP techniques, adopting similar techniques as mentioned above [74]. PE-g-PMMA and Polyclhylcnc-gra/f-poly( -bulyl acrylate) (PE-g-PnBA) were prepared through the combination of metallocene-catalyzed ethylene/10-undecen-l-ol copolymerization and conversion of the copolymer into P E-g-Br, as a macroinitiator, for ATRP. Well-defined graft copolymers, PE-g-PMMA and PE-g-PnBA, were confirmed by analyses of the detached side chains. Resulting PE-g-PMMA worked well as a compatibilizer. 

The copolymer of ethylene withp-MS was available as a PE macroinitiator. PE-g-Br, which works as a PE macroinitiator for ATRP, was prepared from PE-g-MS by bromination with NBS [78], and PE-g-Br can be used to prepare PE-g-PMMA, PE-g-PS and PE-g-PnBA. 

Fig. 14 Plot of a flexural modulus and b flexural strength versus content of polar segment ( PP-g-PMMA, PP-g-PS, PP-g-PnBA, PP-g-OH, PP-g-OH/PMMA (7/3) Blend)...

By this method, the systems were ranked in the order given in Table II with the PS-PnBA combination being the most miscible and the PS-PMMA material being the least miscible. 

Fig. 19. The stress-strain curves recorded for the two triblock copolymer samples during cold drawing of films with a constant rate of 1 mm/min. ABA-isolated clean pnBA central block Mn=65,200 pMMA outer blocks, Mn=13,150, overall Mw/Mn=1.34. ABA-sequential clean pnBA central block, Mn=67,500 pMMA-grad-pnBA outer blocks 13mol% nBA and 87 mol% MMA, Mn=10,600, overall Mw/Mn=1.24. Inset small angle X-ray scattering intensities for these samples. Reprinted with permission from [94]. Copyright (2000) John Wiley Sons, Inc.

Fig. 36. GPC chromatograms of ABC triblock copolymers of pSt-b-pDMS-b-pMMA and pSt-b-pDMS-b-pnBA using hydrosilation and ATRP. Reprinted with permission from [234]. Copyright (1999) American Chemical Society.

Fig. 1. Intensity of two Raman bands of a p-nitrobenzoic acid (PNBA) monolayer, adsorbed in the multilayer structure shown in the inset, vs. a polymethylmethacrylate (PMMA) spacer of thickness d. Open symbols, 1100cm 1 band closed symbols 1597cm-1 band. (Reproduced with permission from ref. 11.)...

When difunctional pnBA was used to prepare ABA block copolymers with MMA using a Ni system, without halogen exchange, it was reported that the mechanical properties of the resulting copolymers were poor compared to those of the copolymers prepared by ionic methods, presumably because of the broad polydispersity of the outer pMMA blocks (see Fig. 9) (147). Complete incorporation of the macroinitiator did not occur until >30% monomer conversion. The block copolymers did, however, microphase separate into ordered structures (148). 

The majority of compositionally different poly(meth)acrylates are immiscible. Nevertheless, there are some examples noted in the literature of miscible combinations. One of the most interesting and well-studied cases involves isotactic PMMA (iPMMA) with syndiotactic PMMA (sPMMA).[149] The miscibility observed may be expected, but the formation of a stereocomplex offered an interesting system to study. The tacticity of PMMA blends with poly(vinyl pyrrolidone) (PVP) affected the blend phase behavior as atatic and syndiotactic PMMA were miscible with PVP, but isotactic PMMA was phase sepa-rated.[150,151] Miscibility with upper critical solution temperature (UCST) behavior was observed for PnBA blends with poly(propylene glycol) (linear and three arm star) oligomers.[152] Poly(vinyl buty-ral)/PMMA blends were found to be phase separated at high MW PMMA.[153] At low MW PMMA (2000-5000 g/mol), miscibility with UCST behavior was observed. The PMAA/PVAc miscibility was... 

PVME was shown to exhibit marginal miscibihty with poly(benzyl methacrylate) with lest behavior [805]. This blend appears to offer distinct similarities to PS/PVME blends. Immisci-bility of PVME with a host of other poly(meth)acrylates was observed. Misdbihty of PVME was reported with PEA, PnPA and PnBA but not PMAc [806]. Lower critical solution temperature behavior was noted for PVME/PEA and PVME/PnBA. PMMA misdbihty with an alternating copolymer of propylene-carbon monoxide was estabhshed by DSC, DMA, FTIR and NMR studies [807]. Poly(4-vinyl pyridine) and poly(2-vinyl pyridine) were found to be miscible with poly(2-hydroxyethyl methacrylate) and poly(3-hydroxypropyl methacrylate), attributed to hydrogen bonding [808]. Poly(2-vinyl pyridine) blends showed lest behavior. 

PC PnBA-PMMA core-sheU modifier Addition of 5 wt% modifier yields 19 times improvement in notched toughness 43... 

Epoxy PnBA-PMMA core-sheU modifier PnBA-PMMA core-shell modifier with PMMA containing epoxy groups showed Kk improvement with optimum interparticle distance of400 nm. 44... 

It was shown that high molar mass, polydisperse acrylic PnBA/PMMA diblock and triblock copolymers prepared by SGl-mediated polymerization were shown to self-assemble into various nanostmctures despite substantial molecular dis-order. ° Lamellae are observed around 55-65 vol.% PMMA, while perfectly symmetrical copolymers adopt a curved interface concave toward PMMA and form cylinders or cylindrical micelles with poor lattice order. This was assigned to unbalanced polydispersity between the two blocks arising from the lack of control over polymerization of PMMA under the synthesis conditions used. 

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