Side-chain Crystallization in Poly n-octadecylmethacrylate

CrystalUne systems containing long sequences of CH2 units are of extraordinary importance in many fields. Polyethylene is the mostly used polymer with a variety of technical appUcations but has a lot of unusual features which are not completely understood. PecuUarities are the large mobility of 

Scattering data for high molecular weight PODMAs in the molten state show a relatively broad prepeak with a maximum at q ps 2.1 nm (Fig- 12.1). According to a Bragg approximation this peak corresponds to a distance 

A schematic picture of the structure of semi-crystalline PODMA is shown in the insets of Fig. 12.1. Basic idea is that the alkyl groups belonging to different monomeric units form layer-like alkyl nanodomains which are separated by main chains. The periodicity dnps of this lamellar structure reflected by the prepeak in x-ray scattering data is indicated. We assume that the alkyl groups within the alkyl nanodomains are basically interdigitated and not to far away from an extended chain conformation. This can be concluded from the dependence of the d ps value on the number of alkyl carbons per side chain C for atactic poly(n-alkyl methacrylates) (Fig. 12.2). The dependence of dnps on (7 is nearly linear and the slope is about 0.13 nm [50] per additional CH2 unit in the side chain corresponding to the value reported for extended chain alkanes (0.127 nm/carbon). 

The halo in the scattering data for amorphous PODMA arotmd q = 13.5 nm reflects the average distance between non-bonded alkyl carbons in the melt (d oc = 0.465 nm). During crystallization a sharp reflex at q 15.1 nm develops on top of the amorphous halo. This corresponds 

A clear trend in the isotherms in Fig. 12.3b is that the crystaUization kinetics slows down if the crystalUzation temperature Tc increases. This 

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