Poly cycloalkyl methacrylates

A series of poly(cycloalkyl methacrylates) has been investigated by dynamic mechanical analysis and solid-state 13 C NMR in order to characterise the 

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Under viscoelastic measurements poly(cycloalkyl methacrylates) show a loss maximum (designated y), located in the very low temperature range (T <-60 °C), as illustrated in Fig. 6 in the case of poly(cyclohexyl methacrylate). Such a series of polymers has been extensively studied by Heijboer in his Ph.D. thesis [5], by performing viscoelastic studies at 1 Hz (sometimes 180 kHz) as a function of temperature and exploring quite a large number of cycloalkyls, either substituted or not. In cyclopentyl, cyclohexyl, cyclohep-tyl derivatives, the y transition was shown to occur at ca. - 185 °C (180 Hz), - 80 °C (1 Hz), - 180 °C (1 Hz), respectively. The associated activation energies, a> are 13, 47, 26kJmol 1 for the cyclopentyl, cyclohexyl, cycloheptyl derivatives, respectively. 

Later on, when high-resolution solid-state 13C NMR became available, these questions concerning motions within the rings of poly(cycloalkyl methacrylates) and the assignment of the specific motion occurring in the case of poly(cyclohexyl methacrylate) were revisited [6]. 

MHz MAS CP DD (magic-angle spinning with cross-polarisation and H dipolar decoupling) 13 C NMR spectra performed at room temperature for the three poly(cycloalkyl methacrylates) (cyclopentyl, cyclohexyl, cyclohep-tyl) are shown in Fig. 8. 

Complementary NMR measurements, such as rises of carbon polarisation in a spin-lock experiment and determination of 13C spin-lattice relaxation times in the rotating frame, Tip(13C), support these conclusions about the correlation times of the side-ring CH and CH2 motions in the various poly(cycloalkyl methacrylates). 

Fig. 3. C,.o as a function of the number of carbons in the alcohol used to make the ester for poly(n-alkyl methacrylates) and poly (cycloalkyl methacrylates). C increases with increasing side group size in each family. For small rings is larger for cycloalkyl versus n-alkyl materials. Reprinted with permission from J. Macromol. Sd., Rev. Macromol. Cbem. Phys., C28(3 4) 393 (1988). Copyright 1988 Marcel Dekker, Inc.

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