Spectra polymethylmethacrylate

Fig. 2 shows one application of ATR depth profiling. In this case, ATR spectra were obtained as a function of angle of incidence from a polymethylmethacrylate (PMMA) film of thickness 0.5 p.m that was deposited onto a germanium hemi-cylinder [4]. The solid line represents the ATR spectrum of PMMA while the squares represent the film thickness that was recovered from the infrared spectra using four different bands. It can be observed that the recovered film thickness was very close to the measured thickness. 

Leadley and Watts used monochromaticized A1K radiation to investigate the interactions that were responsible for adhesion between polymers and substrates [24]. When polymethylmethacrylate (PMMA) was adsorbed onto silicon substrates, the C(ls) spectrum shown in Fig. 21a was obtained. Originally, it was... 

Fig. 14. The electron spin resonance spectrum of y-irradiated polymethylmethacrylate at room temperature, with an analysis above.

Figure 4. HREELS spectra of polymethylmethacrylate films deposited (a) on gold, (b) and (c) on aluminum, (d) on copper (the data for b through d are adapted from ref. 8). All data were collected at room temperature, except spectrum (c) (100 K). 

Polymethylmethacrylate is one of the heterogeneous polymer and ESR studies on this polymer have been done from the early stage of ESR spectroscopy ( 5). Russian researchers reported ESR ctra observed from the PMMA mechano-radicals (28,46-48). No ir formation of the n hano radicals was mentioned by these authors, although PMMA is one of the suitable polymers on wludi Ihe ptdr formation of mechano-radicals is s rched. An ESR spectrum (38, 49) observed at 77 K from the PMMA milled for 24 hrs. is shown as a in Fig. 8. It is well known (50,51) that PMMA radical produced by the main chain scission shows the characteristic quintet-quartet spectrum when PMMA is irradiated by y-rays. It is reasonable to assume that one partner of the pair formation of the PMMA mei no-radical is the species. 

We have applied the ultrafast confocal microscope to map excited state dynamics in thin films of poly(9,9-dioctylfluorene) (PFO, see chemical structure in figure 2(a)), blended with polymethylmethacrylate (PMMA, 10% wt. PFO in PMMA). PFO is a blue-emitting polymer, with an absorption maximum at 385 nm (see Fig. 2(a)), while PMMA is transparent at our pump wavelength and it does not interact with PFO [6] so that it is optically inert. Figure 2(b) shows the macroscopic AT/T spectrum of PFO measured at x = 1 ps at 570 nm probe wavelength we observe a photo-induced absorption (PA) due to photo-generated polarons [7],... 

Kato et al. (92) irradiated polymethylmethacrylate at -196° C under vacuum, and the spectrum shown in Fig. 16 was obtained. This spectrum was identified as due to the free radicals, COOCH3, CHO, and -CH3, which show the singlet, doublet and quartet, respectively. The half-life of methyl radicals at — 196° C was about 5 hr. It is likely that the methyl radicals are produced by the photolysis of ester side groups, just as ethyl radicals are produced after irradiation of polyethyl-methacrylate at —196° C. 

The sample irradiated at — 196° C in the presence of air gave the same spectrum as that under vacuum. This sample, however, gave the spectrum characteristic of peroxy radicals at about — 68° C. An effect of oxygen on radical formation on irradiation with light of 300 nm was also reported (67). Protection against radiation damage in polymethylmethacrylate by ultraviolet light was also reported (98). 

The nine-line spectrum observed after irradiation of polymethylmethacrylate (PMMA) at room temperature has been the subject of much investigation and interpretation. It consists of five well-resolved narrow lines of approximately binomial distribution of intensities and four broader lines evenly distributed between the five (Fig. 14). Identical spectra are obtained at room temperature after UV irradiation or mechanical degradation [41]. A spectrum with similar general features is observed for the other methacrylic and methacrylate polymers. 

Fig. 13. Change in the ultraviolet spectrum of polymethylmethacrylate during irradiation [reproduced with permission from Ref. 12].

The nine-line ESR spectrum observed after irradiation at room temperature has been attributed to the propagating radical formed in reaction (7) [76]. However, according to other workers [77] this signal could also result from the addition of another radical to residual monomer molecules. It is of interest to note that the quantum yield of main chain scissions is five to ten times smaller than the quantum yield of side group splitting by reaction (5), whereas both processes occur with the same yield in the radiolysis of polymethylmethacrylate [78]. This indicates that only a fraction of the macro-radicals decompose according to reaction (7) at room temperature. 

Quantum yields of formation have been measured for formaldehyde (2 x 10-2), methanol (1.9 x 10-3) and methyl formate (8 x 10-3) [82]. A modification of the absorption spectrum of polymethylacrylate during irradiation has also been observed (Fig. 14). [82]. The change is similar to that observed with polymethylmethacrylate in the same experimental conditions (Fig. 13) and is probably to be ascribed to the same origin. The photodegradation of polymethylacrylate can be visualized as... 

Figure 3.5 shows the Fourier transform infrared spectrum of polymethylmethacrylate (PMMA). Figure 3.6 (top spectrum) shows a spectrum of an acrylonitrile-butadiene copolymer of unknown composition. The lower spectrum is a match obtained from one of a range of standard copolymers of known composition demonstrating that the unknown copolymer contains between 30 and 32% acrylonitrile and between 70 and 68% butadiene. 

A C-NMR spectrum of a polymethylmethacrylate - methacrylic acid copolymer is shown in Figure 3.19 (a). The spectrum demonstrates the acidic group and the ester group resonances. 

Polymethylmethacrylate (PMMA) is another polymeric material frequently employed for microfluidics and micro fuel cells [4]. PMMA is one of the thermoplastic polymers that is usually linearly linked and can be softened by applying heat at above the glass transition temperature [8]. PMMA has a noncrystalUne structure with 92% light transmittance in the visible spectrum. This material also has other excellent properties such as low frictional coefficient, high chemical resistance, and good electrical insulation. All these features and properties make PMMA a good substrate for microfluidic devices, especially for those involved in chemical applications [8]. 

Borsali, et al. studied dynamic light scattering spectra of 970 kDa polystyrene 950 kDa polymethylmethacrylate toluene. PMMA and toluene form an isorefrac-five pair(70). Semiquanfitafive experimental tests were made of the theoretical work of Benmouna, et a/. (67). When neither polymer was dilute, the observed spectrum was biexponenfial, even though only one macrocomponent scatters light. The mode... 

Sun and Wang report a series of studies of polystyrene polymethylmethacrylate mixtures (in benzene, dioxane, and toluene, respectively) using light scattering spectroscopy as the major experimental technique(78-80). Both polymers were in general nondilute. Neither polymer is isorefiractive with any of the solvents. The objective was to study the bimodal spectra that arise under these conditions and to show that the two relaxation times and the mode ampUtude ratio can be used to infer diffusion and cross-diffusion coefiBcients of the two components. Experimental series varied both the total polymer concentration and the concentration ratio of the two components. The theoretical model predicts a biexponential spectrum. The experimental data were fitted by a bimodal distribution of relaxation rates or by a sum of two Williams-Watts functions. The inferred self-diffusion coefiBcients of both species fall with increasing polymer concentration. 

The effect on the polymethylmethacrylate spectrum when the polymer is incorporated into a copolymer is nicely demonstrated in the following... 

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