Thick PMMA films methacrylate

Neckers and coworkers could, however, generate hexacene photochemically after the photoprecursor had been embedded in a poly(methyl methacrylate) matrix (PMMA) [29]. Due to immobilization of the molecules, this matrix prevents photodimerization of hexacene and minimizes contact with ambient oxygen. Within the PMMA film ( 0.5 mm thick), hexacene is stable under ambient conditions overnight, but it is slowly oxidized by diffusion of molecular oxygen into the PMMA matrix [29]. 

Winnik et al. [53] used time-resolved fluorescence spectroscopy (direct non-radi-ative energy transfer experiments) to determine the interface thickness in films of symmetric poly(styrene-fc-methyl methacrylate) (PS-PMMA) block copolymers labeled at their junctions with either a 9-phenanthryl or a 2-anthryl group. The corrected donor fluorescence decay profiles were fitted to simulated fluorescence decay curves in which the interface thickness 8 was the only adjustable parameter. The optimum value of the interface thickness obtained was 6 = 4.8 run. In similar studies [54—57], the same authors determined the interface thickness value 6 = 1.6 nm in mixtures of two symmetrical poly(isoprene-b-methyl methacrylate) (PI-PMMA) block copolymers of similar molar mass and composition [54] the interface thickness value 8 = 1.1 nm for the lamellar structures formed in films of symmetric PI-PMMA diblock copolymers bearing dyes at the junctions [55] a cylindrical interface thickness value of d slightly smaller than 1.0 nm in films consisting of mixtures of donor- and acceptor-labeled PI-PMMA (29vol% PI) that form a hexagonal phase in the bulk state [56] and the interface thickness 8 = 5 run on the diblock copolymer poly(styrene-l>-butyl methacrylate)(PS-h-PBMA) [57]. 

In the cases of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride-vinyl acetate) (PVC/PV Ac), these polymers generate much more gas during irradiation than polystyrene. Thus, even if the gases accumulated in microvoids, where their enhancement of creep rate might be lessened, the local gas concentration between the polymer chains should still be much higher than in the case of polystyrene. One would thus expect to see an effect of film thickness on creep rate for these polymers. 

Fig. 18. Induced open-circuit voltage in elongation plotted against amplitude at the end of film for as-cast films polypropylene (PP), high-density polyethylene (PE(H)), low-density polyethylene(PE(L)), polystyrene PS), and poly(methyl methacrylate) (PMMA). Span length = 3.6 cm. Electrode area=2.5 x 2.5 cm2. Film thickness =0.5 mm. Reproduced from Furukawa and others [J. Appl. Polym. Sci. 12, 2675 (1968)] by permission of John Wiley Sons, Inc.

In another report, instead of direct x-ray ablation, an x-ray mask, which was 10-pm-thick Au on a Kapton film, was employed to ablate a PMMA wafer. Then the ablated PMMA wafer was developed. For sealing, a PMMA cover was first spin-coated with a 2-pm layer of poly(butyl methacrylate-co-methyl methacrylate) and then thermally bonded to the PMMA plate (120°C for 1 h) [200]. 

Samples. Polyethylene terephthalate (PET) samples are industrial (Mylar) biaxially oriented films (10 pm thick). Polymethyl-methacrylate (PMMA) has been spin coated on microscope glasses from a PMMA (1) / CHjClj (9) solution, giving thin layers of a few hundred A thickness. 

Another type of dependence of effective interfacial width wD on film thickness D was observed [130] for immiscible mixture of deuterated polystyrene (dPS) and poly(methyl methacrylate) (PMMA) (at T TC) an increase, from wd=1.8(4) nm for a dPS layer thickness D=6 nm to wd(D=100 nm)=2.5(4) nm, follows the logarithmic dependence wD°clnD (intrinsic interfacial width w= 1.5 nm). This may reflect [6,224] long range forces acting from the external interfaces on the internal interface Ie(x,y). On the contrary, the relation wd D1/2 found for random olefines [121] corresponds [6,224] to short range forces. We note also that capillary waves in dPS/PMMA system were observed [130] already for the thickness-to-intrinsic width ratio D/w<85 ... 

In another recent report, a thin layer (-200 nm) of homopolymer over BCP film (-80 nm) led to formation of nano-pores (-15 nm diameter) within the films after etching by acetic acid. In this case, small cylindrical nanodomains of poly(methyl methacrylate) (PMMA) are found in polysty-rene-block-PMMA (PS-b-PMMA) when the thickness of the BCP membrane is about 80 nm, which reaches the limit of... 

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