A silica-poly(methy1 methacrylate) (PMMA) composite was prepared by condensation polymerization of a 2 nm shell of the silane coupling agent 3-(trimethoxysilyl)propyl methacrylate (TPM) on the surface of 10.5 nm diameter sol-gel colloidal silica particles followed by free-radical Folymerization of a 50 wt % dispersion of the TPM-silica in methyl methacrylate. Cross-polarization combined with magic angle spinning and high-power decoupling (CPIMAS) and single-pulse 29Si NMR s p x t r a together with quasi-adiabatic cross-polarization (QACP) 13C NMR spectra provided quantitative analyses of the structural components of the parent silica, the TPM-silica, and the composite. The parent silica contained one ethoxy group and eleven hydroxy groups per ten silicon atoms. The TPM-silica containcd one residual methoxy group per TPM group and no residual hydroxy groups. Polymerization with M.MA consumed 85% of the methacrylate groups of the TPM. Time constants T l p~ for proton spin-lattice, relaxation in the rotating frame detected via 13C and 29Si CPMAS spectra showed rapid spin diffusion bstween all CH protons in the samples, but not between the CH protons and the OH protons that cross-polarize 29Si atoms in the parent silica. Time constants Tlpc for carbon spin-lattice relaxation in the rotating frame showed that the TPM-silica has substantial motion at kilohertz frequencies leading to fast relaxation, whereas the PMMA composite is more rigid and the ethoxy groups in the parent silica arc more mobile.Measurements of lH-lH dipolar transverse relaxation times via 13C and 29Si detection showed decreasing strengths of homonuclear dipolar interactions due to increasing molecular motion in the order composite > TPM-silica > OH groups in parent silica.

Hypercrosslinked polystyrenes, synthesized by reaction of linear or lightly crosslinked polystyrene with chloromethyl methyl ether (CME) and a Lewis acid in a good solvent, swell even in nonsolvents for polystyrene. Structures and dynamics of hypercrosslinked polystyrenes in both dry solid and solvent‐swollen gel states have been determined by 13C‐NMR spectroscopy. Deconvolution of 13C solid‐state CP/MAS spectra gave the relative numbers of quaternary carbon atoms in monosubstituted and disubstituted benzenes. A typical sample, crosslinked by reaction of a mixture containing 0.5 mol of CME per mol of repeat units, contains 35% of unreacted and 65% of crosslinked aromatic rings, and no residual chloromethyl groups. Gels swollen in CDCl3 and in CH3OH have residual static dipolar interactions enabling crosspolarization and require magic angle spinning (MAS) and high power 1H decoupling to reduce chemical shift anisotropy from ∼ 104 Hz to ∼ 103 Hz. A single proton spin‐lattice relaxation time in the rotating frame measured from all peaks in the 13C spectra of dry samples indicates homogeneity on a nanometer scale. Proton NMR line widths indicate no substantial molecular motions in a dry hypercrosslinked polystyrene up to at least 200°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 695–701, 1997

The viscosities of dimethyl formamide solutions of acrylonitrile‐acrylate copolymers were determined at 30,35,40 and 45°C using an Ubbelohde viscometer. The viscosities of homopolymer solutions were also studied. The homopolymers of aerylonitrile and also of methyl, ethyl and butyl acrylates were synthesised in the laboratory. The random copolymers were synthesised by a solution polymerisation technique keeping the acrylonitrile: acrylate ratio as 1:1, 1:2 and 1:3 (w/w). The intrinsic viscosity for each system was computed as a function of temperature. The activation parameters of viscous flow were calculated using the Frenkel‐Eyring equation. Voluminosity for all systems was also computed. From intrinsic viscosity and voluminosity data it was concluded that the polymer molecules are spherical in the dimethyl formamide solutions.

SYNOPSISVarious homopolymers and copolymers of methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile in different feed ratios were synthesized. These were characterized by IR, 13C-NMR, DSC, DTA, and TGA. Spectroscopic characterization helped in differentiating copolymers of different mol ratios. Thermal analysis revealed different degradation patterns for homopolymers and copolymers. The temperature and energy changes associated with various phase transitions were dependent on the chemical composition of homo-and copolymers, as expected. 0 1993 John Wiley & Sons, Inc.

Hypercrosslinked polystyrenes, synthesized by reaction of linear or lightly crosslinked polystyrene with chloromethyl methyl ether (CME) and a Lewis acid in a good solvent, swell even in nonsolvents for polystyrene. Structures and dynamics of hypercrosslinked polystyrenes in both dry solid and solvent-swollen gel states have been determined by 13 C-NMR spectroscopy. Deconvolution of 13 C solid-state CP/MAS spectra gave the relative numbers of quaternary carbon atoms in monosubstituted and disubstituted benzenes. A typical sample, crosslinked by reaction of a mixture containing 0.5 mol of CME per mol of repeat units, contains 35% of unreacted and 65% of crosslinked aromatic rings, and no residual chloromethyl groups. Gels swollen in CDCl 3 and in CH 3 OH have residual static dipolar interactions enabling crosspolarization and require magic angle spinning (MAS) and high power 1 H decoupling to reduce chemical shift anisotropy from Ç 10 4 Hz to Ç 10 3 Hz. A single proton spin-lattice relaxation time in the rotating frame measured from all peaks in the 13 C spectra of dry samples indicates homogeneity on a nanometer scale. Proton NMR line widths indicate no substantial molecular motions in a dry hypercrosslinked polystyrene up to at least