Makrolons

Makrolon CD 2005, Bayer AG (Germany) and Mobay Corp. (United States) (193). 

Polycarbonates are an unusual and extremely useful class of polymers. The vast majority of polycarbonates are based on bisphenol A [80-05-7] (BPA) and sold under the trade names Lexan (GE), Makrolon (Bayer), CaUbre (Dow), and Panlite (Idemitsu). BPA polycarbonates [25037-45-0] having glass-transition temperatures in the range of 145—155°C, are widely regarded for optical clarity and exceptional impact resistance and ductiUty at room temperature and below. Other properties, such as modulus, dielectric strength, or tensile strength are comparable to other amorphous thermoplastics at similar temperatures below their respective glass-transition temperatures, T. Whereas below their Ts most amorphous polymers are stiff and britde, polycarbonates retain their ductiUty. 

Today about 75% of the market is held by General Electric and Bayer with their products Lexan and Makrolon respectively. Other manufacturers are ANIC (Italy), Taijin Chemical Co., Mitsubishi Edogawa and Idemitsu Kasei in Japan and, since 1985, Dow (USA) and Policarbonatos do Brasil (Brazil). Whilst this market is dominated by bis-phenol A polycarbonates, recent important developments include alloys with other thermoplastics, polyester carbonates and silicone-polycarbonate block copolymers. 

Block copolymers of polycarbonates and silicone polymers have also been commercially marketed (e.g. Makrolons KU 1-1198 and KU 1-1207). These block copolymers show a marked increase in toughness at low temperatures coupled with reduced notch sensitivity. (They show little improvement in toughness at normal ambient temperatures.)... 

The repeat unit in the Phenoxy molecule is longer by two carbon atoms than that of PC. Otherwise the molecular structures of the two polymers are similar. Eq. (7.8) should, therefore, apply also to PC, at least approximately. 8C = 8.9 pm was measured for the crack opening displacement in a Makrolon sheet (Mn = 9.5 kg/mol) by Fraser and Ward [80], An estimate of the molecular mass between entanglements according to Eq. (7.8) yields Mc = 1.7 kg/mol. This result is not very different from the value of 2.5 kg/mol for IVIC in PC as given in Table 3.2. 

These results at 20° C refer to low stress moulded parts made from Makrolon. The chemical resistance of this material may be affected by mechanical stresses and high temperatures. The polymer High Density 3... 

Much the most important polycarbonate in commercial terms is made from 2,2-di(4-hydroxyphenyl)propane, commonly known as bisphenol A. This polymer was discovered and developed by Farbenfabriken Bayer [92], The synthesis and properties of this and many other polycarbonates were described by Schnell in 1956 [93], The polymer became available in Germany in 1959, and was given the trade name Makrolon by Bayer (in the USA, Merlon from Mobay). General Electric (GE) independently developed a melt polymerisation route based on transesterification of a bisphenol with DPC [94], Their product, Lexan, entered the US market in 1960. The solution polymerisation route using phosgene has since been displaced by an interfacial polymerisation. 

Acrylite, Apec, Calibre, Lexan, Makrolon, Sinvet, Xantar. 

Plasticization of the Polycarbonate. Makrolon S of Bayer A.G. was used in the experiments. The intrinsic viscosity of this polymer is about 0.55 dl./gram. 

Abstract Makrolon , a commercially available polycarbonate with a glassy ultramicroporous structure (mean pore-volume 0.1 nm3), was often employed as sensitive layer for optical sensors in recent years. Due to the definite pore volume-distribution, it can be used as a size-selective sensitive layer. The interaction behaviour of Makrolon of different layer-thicknesses under the influence of methanol, ethanol and 1-propanol is characterized by Spectral El-lipsometry (SE), Surface Plasmon Resonance Spectroscopy (SPR)... 

Interaction Behaviour of the Ultramicroporous Polymer Makrolon by Optical Spectroscopic Methods... 

In this study, for an accurate understanding of the interaction behaviour of the ultramicroporous polymer Makrolon, as a receptor, under the influence of three alcohols is investigated by three transduction methods Spectral ellipsometry (SE), RIfS and SPR. 

Makrolon has a mean free pore-volume of 0.1 nm3 and the width at half-height of the corresponding distribution is 0.04 nm3 [22], The polymer layer reacts to the exposition of the analyte molecules by swelling and by changes of the refractive index. Due to the pore-volume distribution (see Fig. 1), the interaction kinetic depends on the molecule size [23], The analytes used in this work are methanol with a size smaller, ethanol with a size almost equal to and 1-propanol with a size bigger than the mean free pore-volume. 

At higher concentrations, when all available pores are filled, a further swelling of the polymer layer should be observed. The refractive index of Makrolon is d = 1.586 and because of the sorption of the analytes with a lower refractive index into the polymer matrix, it should decrease. By the observation of changes of the refractive index on the one hand and the determination of changes of the layer thickness on the other hand, statements about the interaction behaviour will be made. 

Another objective of this work is the interaction behaviour of layers of different thicknesses under the influence of the same analyte. Thus, Makrolon layers between 35 nm and 455 nm were prepared and characterized under the effect of the above named analytes with the considered detection methods. 

The investigated polymer is a glassy, ultramicroporous polymer (Makrolon M2400, Bayer AG Leverkusen, Germany). All measurements were performed below the glass transition temperature (7g = 145 °C), so the glassy polymer chains are restricted in motion and cannot completely homogenize. 

All sensitive layers were prepared from solutions of Makrolon in mixtures of chloroform and dichlorobenzene by a spin-coating process. By adjustment of the rotation speed and time the thickness of the layers were varied between 35 nm and 455 nm. Layer thicknesses and refractive indices were determined by spectral ellipsometry. Furthermore the polymer thicknesses were verified by a surface profilometer (Alpha Step 500, Tencor Instruments, Mountain View, USA). 

The interaction behaviour of the homologous alcohols methanol, ethanol and 1-propanol and the ultramicroporous polymer Makrolon was investigated by three different optical methods spectral ellipsometry, surface plasmon resonance and reflectometric interference spectroscopy. 

For the characterization of the interaction behaviour, six ultramicroporous layers of thicknesses between 35 nm and 430 nm have been exposed to the three alcohols. In Fig. 3 the SPR measurements of a 200 nm Makrolon layer with methanol ( d = 1-329), ethanol ( d = 1.361) and... 

Fig. 2 Relative change in the refractive index (gray squares) and relative change in the physical thickness (open cycles) of a Makrolon layer of 170 nm during exposition to different concentrations of 1-propanol, measured by spectral ellipsometry...

Fig. 4 Eight concentrations of methanol exposed to six different Makrolon layers between 35 and 430 nm. The shift of the SPR resonance wavelength is plotted versus the saturation pressure of the alcohol...

The interaction behaviour of five Makrolon layers of different thicknesses between 70 nm and 455 nm and the three homologous alcohols was investigated by reflecto-metric interference spectroscopy. In Fig. 5 the changes of the optical thickness of a 205 nm layer is plotted versus the concentrations of the three homologous alcohols. For methanol there is a relatively linear increase of the change in optical thickness. For the two greater analytes, the curves are more arcuated and the Henry-Langmuir-behaviour can be seen more clearly. 

In Fig. 6 the saturation signals for the five Makrolon layers for methanol are given. The changes of optical thickness depend on the thickness of the sensitive layer, but they are not growing linearly with the layer thickness. For the 70 nm layer the changes are very small and the signal is very low which can be explained by the... 

Fig. 5 The change in the optical thickness of a 205 nm thick Makrolon layer plotted against the concentrations of the three homologous alcohols, measured with RIfS...

The 35 nm Makrolon layer shows a relatively linear signal with only a slight curvature in the SPR-measurement. 

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