Glass transition temperatures of a very wide molecular-weight range of ethylene oxide polymers were measured by mechanical loss and by broadline NMR. Starting at about -95°C for ethylene glycol, the glass transition rises to a maximum of -17° for molecular weight 6000 and then drops off to -53° for polymers with molecular weights greater than 200 000. This unusual behavior is probably caused by the high crystallinity of the intermediate molecular-weight polymers.

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High‐resolution nuclear magnetic resonance (NMR) spectroscopy has been used for the past several years quite effectively in both the qualitative and quantitative determination of the molecular chain structures and compositions of various polymeric systems. Valuable structural information obtained from such NMR studies has included: (1) detailed stereo chemical configuration (both tacticities and stereoblock sizes) of the polymer chains, (2) copolymer compositions, (5) sequence distribution studies in copolymers, (4) determination of modes of monomer addition in both homopolymers and copolymers, and (5) extent of head‐to‐head structures. Currently, only H1 and F19 NMR techniques are being used in the elucidation of organic polymer structures, for reasons primarily of instrumental sensitivity but also involving general applicability. Examples of the utility of F19 and H1 NMR, as well as double‐resonance techniques, to determine chain structure and composition of fluorine‐containing polymers are presented in this paper. In particular, conclusive proof of a substantial amount (10–12%) of head‐to‐head structure and the detailed assignment of the F19 chemical shifts in poly(vinylidene fluoride) is presented. The existence of a very large amount (26–32%) of he ad‐to‐head structure in both experimental and commercial samples of poly(vinyl fluoride) is also shown (although the detailed assignment of the F19 NMR spectral peaks has not yet been completed); this indicates that about one monomer unit in every six or so is added “backwards” to the growing polymer chains during free‐radical homopolymerizations. Increase in the amount of head‐to‐head structure with increase in polymerization temperature is also observed for poly(vinyl fluoride).

High-resolution nuclear magnetic resonance spectra of o-dichlorobenzene solutions of isotactic, syndiotactic, and atactic 1,2-polybutadiene are presented and interpreted. The methylene protons of isotactic 1,2-polybutadiene are nonequivalent, differing in chemical shift by 0.2 ppm, indicating that methylene proton resonance can provide information about the meso dyad content of 1,2-polybutadiene. The chemical shifts of methine type vinyl protons (-CH=C) in isotactic and syndiotactic 1,2-polybutadiene differ by 0.14 ppm, indicating that the resonance of such protons can provide information about the relative amounts of isotactic, heterotatic and syndiotactic triads in 1,2-polybutadiene. The resonances of other protons in 1,2-polybutadiene are not useful for microstructure studies, as they are rather insensitive to configurational differences.