James E. Guillet

Study of polymers by inverse gas chromatography

As a result of the experimental work summarized in this review the value of the gas chromatographic method for studying polymers seems to be well established. Surface and bulk properties of polymers can be measured both from a thermodynamic and kinetic point of view. Because of its simplicity and precision it should become the method of choice for the study of thermodynamic interactions of small molecule “probes” or solutes in systems where the polymer is the major phase. Further advances in the kinetic theory of the GC process should provide even more reliable data about time dependent processes such as diffusion, adsorption, complex formation and possibly even chemical reaction.

Measurement of solubility parameters by gas-liquid chromatrography

Abstract Gas-liquid chromatography has been used to calculate thermodynamic data for a variety of probe molecules in three polymers at 25°C. The method of Guillet and co-workers has been applied to calculate solubility parameters, σ, and good agreement was found with literatue values. The results avoid extrapolation from higher temperatures and add further validity to the method. Discussion of the role of σ in polymer solution thermodynamics is also given.

Estimation of solubility parameters for poly(vinyl acetate) by inverse gas chromatography

Abstract Infinite dilution weight fraction activity coefficients, (a1/w1∞, partial molar heats of mixing, Δ H 1∞, and Flory—Huggins interaction parameters, χ, were determined for 11 hydrocarbons in poly(vinyl acetate) (120–150°C) by the gas chromatographic method. Hildebrand—Scatchard solubility theory was combined with Flory theory in order to estimate infinite dilution solubility parameters (δ2∞) for the polymer at 135°C (8.5 ± 0.4) and 25°c (10.2 ±0.5), respectively.

PHOTOCHEMISTRY OF cis-POLYISOPRENE AND ITS SINGLET OXYGEN ADDUCT

Abstract— Reaction of singlet oxygen (1Δg, 1O2) with cis‐polyisoprene yields an allylic hydroperoxide with an olefinic double bond shifted in the polymer chain. The photochemical decomposition of the resultant hydro‐peroxide and the subsequent polymer chain scission kinetics have been studied in the absence of oxygen. Quantum yields of hydroperoxide decomposition range from 3.1 to 8.4 in cyclohexane, depending on the initial amount of hydroperoxide in the polymer. On the other hand, the quantum yields for polymer chain scission are low, and vary with the frequency of the incident light. The ratio for number of polymer scissions per number of hydroperoxy groups decomposed is of the order of 10‐2. The polymer chain degradation is sensitized by the addition of ketones. Based on these data, a reaction mechanism for the overall photodegradation of the cis‐polyisoprene initiated by singlet oxygen is proposed.

Atomic force microscopy of polymer crystals: 4. Imaging of oriented isotactic polypropylene with molecular resolution

Abstract Atomic force microscopy (AFM) was used to visualize microfibrils and macromolecules in uniaxially oriented isotactic α-polypropylene. AFM images showed fibrils with a typical average diameter of 150 nm. High magnification scans unveiled individual macromolecules with a 1.17 nm chain-chain distance. Based on this value it is suggested that the (110) crystal plane was resolved in the AFM images.

Studies of the antenna effect in polymer molecules: Photosensitized oxidation of perylene in an aqueous solution of poly(sodium styrenesulfonate-co-2-vinylnaphthalene)

Abstract The photosensitized oxidation of perylene solubilized in an aqueous solution of poly(sodium styrenesulfonate-co-2-vinylnaphthalene) (PSSS-VN) was studied. The process was shown to occur in the hydrophobic polymeric microdomains where perylene is solubilized. Two major secondary oxidation products, 3,10-perylenequinone and 1,12-perylenequinone, were identified. On the basis of the product analysis, a mechanism for the photosensitized oxidation of perylene in aqueous PSSS-VN solution is proposed involving the participation of singlet oxygen.

Studies of the antenna effect in polymer molecules 25. Photozymes with rose bengal chromophores

Abstract Several copolymers of poly(sodium styrenesulfonate-styrene-vinylbenzylchloride) and poly(sodium styrenesulfonate-2-vinylnaphthalene- vinylbenzylchloride) containing various amounts of rose bengal chromophores attached to the polymer chain were synthesized. The copolymers are soluble in water and can solubilize large hydrophobic compounds. They are efficient genarators of singlet oxygen, and act as photosensitizers in the oxidation of singlet oxygen acceptors which are dissolved in the water phase and solubilized in the hydrophobic polymeric microdomains.

Studies of the antenna effect in polymer molecules. 29. Synthesis and properties of poly[sodium styrene sulfonate-co-(4-acryolyloxyphenyl)-10,15,20-tritolylporphyrin] in aqueous solution

Abstract The novel water soluble antenna polyelectrolyte: poly[sodium styrene sulfonate-co-(4-acryolyloxyphenyl)-10,15,20-tritolylporphyrin] (PSSS-Po) was synthesised, and its photophysical and photochemical properties were studied. Solubilisation of the various molecular probes such as pyrene or perylene in aqueous solution of the PSSS-Po proved that the polymer chain adopts the compact conformation. The interior of the polymer pseudomicelle is significantly less polar than water. The effective quenching of polymeric porphyrin fluorescence by sulfopropyl viologen (SPV) can be explained considering the possibility of electron transfer from the singlet-excited state of Po to SPV. This has been supported by measuring an absorption spectrum for PSSS-Po/SPV system after selective irradiation of Po chromophores. The formation of the new absorption bands characteristic for SPV − radical anion indicated that the charge separation was achieved in that system.

Studies of the antenna effect in polymer molecules. 28. Photo-Fries rearrangement of 1-naphthyl acetate in aqueous solutions of poly(sodium styrenesulfonate-co-2-vinylfluorene)

The photo-Fries rearrangement of 1-naphthyl acetate (NA) in aqueous solutions of the novel antenna polyelectrolyte, poly(sodium styrenesulfonate-co-2-vinylfluorene) (PSSS-VF), was studied. Three copolymers with different fluorene (Fl) chromophore contents were synthesized. The solubilizing abilities of the PSSS-VF copolymers in aqueous solution were tested using perylene as a probe. The polarity of the polymeric medium was shown to be lower than that of the interior of typical surfactant micelles. It was demonstrated that electronic excitation energy can migrate along the polymer chain before being transferred to the solubilized probe molecule. The reaction of NA is sensitized efficiently by light absorbed by the polymeric fluorene chromophores. It was found that the product distribution of the reaction strongly depends on the content of fluorene in the copolymer. The reaction in aqueous solutions of PSSS-VF rich in Fl chromophores occurs with high selectivity to form the cage product, 2-acetonaphthol (2-AN) in 95% yield. Polymeric sensitizers with low fluorene content (∽5%) gave 90% yields of the non-cage product 1-naphthol. Both are more selective than when the Fries reaction is carried out in methanol solution.

The use of inverse gas chromatography to study liquid crystalline polymers

Abstract Liquid crystalline polymers are currently among the most widely studied classes of polymeric materials. The correlation of mesophase and liquid crystalline polymer molecular structures with observable physico-chemical properties is a major objective. In this work, inverse gas chromatography (i.g.c.) was used to determine the transition temperatures of a main chain, liquid crystalline, biphenyl-based organic polyester. The transition temperatures determined by using this method agree very well with those determined by other techniques. In addition, the i.g.c. experiment gives physico-chemical parameters for the interaction of probe molecules (saturated and aromatic hydrocarbons) with the liquid crystalline phases. Thus, enthalpies of mixing and solution of probe molecules in the polymer were estimated, and activity coefficients were calculated. From a single i.g.c. experiment, a wide range of information regarding the temperature-dependent properties of a liquid crystalline polymer was obtained.