Solid-state NMR investigation of the effects of structural modifications on molecular motions and packing in poly(carbonate)s, poly(ester)s, and poly(estercarbonate)s

Poly(carbonate)s, poly(ester)s, and poly(estercarbonate)s are high temperature thermoplastics with commercially attractive mechanical and optical properties. Mechanical properties such as impact resistance are linked to molecular motions and are affected by structural modifications. Effects of main and side chain modifications on phenylene ring dynamics in modified poly(carbonate)s, poly(ester)s, and poly(estercarbonate) s based on 1,1′-bis(4-hydroxyphenyl)-cyclohexane (ZPC), 1,1′-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (TMCPC) and 1,1′-spiro[bis(3,3dimethyl-6-hydroxyindane)] (SBIPC) were investigated using dipolar rotational spin echo (DRSE) 13C NMR at 15.1 MHz. The results show that the polymer large-amplitude phenyl-ring 180°-flip motions are not affected by substitution of either flexible or rigid units in the polymer backbone if a comparable steric size is maintained. However, replacement of isopropylidene units by bulkier cyclohexylene and trimethylcyclohexylene rings cause moderate suppression of phenyl-ring 180°-flip motions. The flips are completely arrested by the more drastic spiro-linkage in SBIPC based polymers.; All the side chain aliphatic rings in TMCPC and SBIPC polymers are mobile; only those in ZPC based polymers with main chain cyclohexyl rings are immobile on the DRSE time scale. This is because of tightening of chain packing attributed to flexibility of main chain cyclohexyl rings.; The mechanically important 1–100 Hz (slow) motions in crystalline bisphenol A, PC, ZPC, TMCPC, SBIPC and [ring-fluoro]polycarbonate (rFPC) were investigated by centerband only detection of exchange (CODEX). The results show that motions in rFPC are facilitated by a lattice reorganization that involves a sizeable reorientation of the isopropylidene moiety. The CODEX results are consistent with the sub-T_g relaxations of these polymers. All the polymers that are lossy close to 300 K have significant pure CODEX signals. PC and SBIPC are not lossy at 300 K. The pure CODEX intensities of PC are small because chain motion is too fast to be CODEX active. The CODEX intensities for SBIPC are small because SBIPC is rigid.; Chain packing was explored using rotational-echo, double resonance (REDOR) NMR. 13C{lcub}19F{rcub} REDOR experiments performed on homogeneous blends of rFPC and methyl-fluorinated polycarbonates with carbonyl-carbon 13C-labeled polycarbonate, indicate a preference for the isopropylidene of one polycarbonate chain to be proximate to the carbonate of a nearest-neighbor chain.