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The photoinitiated polymerization of epoxidized hydroxytelechelic cis-1,4-polyisoprene and of a dual system (epoxidized/acrylated) telechelic cis-1,4-polyisoprene in the presence of 2,2-dimethyl-1,2-hydroxyacetophenone or/and hexafluoro-phosphate triarylsulfonium salt has been studied by real-time infrared spectroscopy. The synthesis of photosensitives oligoisoprenes was achieved by chemical modifications of hydroxytelechelic cis-1,4-polyisoprene obtained by controlled degradation of high molecular weight cis-1,4-polyisoprene. Then, the effect of light intensity, photoinitiator concentration, addition of reactive diluent and concentration of functional groups on the photopolymerization process was evaluated. Concerning the cationic process, the results showed that the kinetic profile improves when photoinitiator concentration and light intensity increase. The optimum concentration of triarylsulfonium salt used as photoinitiator was determined as 5% (w/w) and the optimum light intensity was 50 mW cm−2. Reactive diluent (3-ethyl-3-hydroxymethyl oxetane) addition greatly improves the ultimate conversion and the polymerization rate. Subsequently, the photopolymerization kinetic of a dual epoxidized/acrylated system was studied. The results obtained using different photoinitiator mixtures and different intensity of irradiation showed that the crosslinking of acrylate functions at the chain-end prevents the progression of the cationic process at the oxirane groups along the chain. Thus, the mobility of the cationic reactive centers was restricted by the crosslinking at the high conversion of the acrylate double bonds. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

New photosensitive oligoisoprenes were synthesized by controlled degradation of high molecular weight cis-1,4-polyisoprene and successive chemical modification of the chain-ends. Oligomers with diacrylate extremities were synthesized, characterized, and used in photocrosslinking reactions in different conditions. The photoinitiated polymerization of the diacrylate oligoisoprenes was carried out using 2,2-dimethyl-2-hydroxyacetophenone (Darocur 1173) as initiator and the reaction was monitored by photocalorimetry-DSC and real time FTIR spectroscopy. The influence of oxygen, photoinitiator concentration, light intensity, diluting agent, and oligomers molecular weight on the reaction rate was investigated. It was found that the presence of oxygen does not influence the photopolymerization kinetics of the diacrylate oligoisoprenes. Maximum conversion was obtained for a photoinitiator concentration of 5% (w/w) and for a light intensity of 13.5 mW/cm2. Decreasing the formulation viscosity by addition of a diluent (1,6-hexanediol diacrylate) raised the photopolymerization rate, by increasing the reactive species mobility. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

New segmented polyurethanes (thermoplastic-elastomers) based on previously described hydroxytelechelic cis-1,4-polyisoprene (HTPI), miscellaneous isocyanates and chain extenders at various equivalent ratios were prepared by the classical one-shot method. The influence of the nature of isocyanate and chain extender, as well as their equivalent ratios, on the mechanical and thermal materials behavior was investigated. Thus, a comparative assessment of material properties was performed. Microphase separation of hard and soft segments was observed by DMTA, DSC and AFM. Moreover, according to Thermogravimetric Analysis (TGA), linear relationships depending on the isocyanate and chain extender nature were found between the weight loss (%) and the percentages of hard segments. A classification of thermal stability in terms of weight loss was established. With the aim of a thermo-mechanical comparative study, polyurethane elastomers based on HTPI and isocyanates without chain extender, were also synthesized. [ABSTRACT FROM AUTHOR]