A new morphology of crew-cut aggregates prepared from highly asymmetric triblock copolymers of 5-(N,N-diethylamino)isoprene and styrene in dilute solution is reported. After quaternization of the polar block, using dimethyl sulfate, the copolymers consist of a long block of polystyrene (PS) with short poly[5-(N,N,N-diethylmethylammonium)isoprene] (PAI) blocks at both chain ends. The aggregates were prepared by first dissolving the copolymers in a common solvent for both blocks and then adding water to induce the segregation of the PS chains. 1,4-Dioxane, THF, or a DMF/THF mixture was used as the common solvent in the preparation of these structures. The bowl-shaped aggregates are essentially highly polydisperse spheres, containing an asymmetrically placed single void space, which has broken through the surface. The continuous phase is composed of an assembly of reverse micelles (PAI core and PS corona) with hydrophilic PAI chains surrounding the structure at the polymer/aqueous solution interface. It is believed that the formation of the bowl-shaped morphology is under kinetic control and does not represent an equilibrium state. A possible mechanism for the formation of this aggregate is proposed, based on two other previously reported crew-cut morphologies from diblock copolymers. This study illustrates the importance of the preparative conditions on the self-assembly of nonequilibrium aggregates from amphiphilic block copolymers.

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Polyurethanes can be prepared using polyols obtained from vegetable oils in natura, such as castor oil, or from functionalized vegetable oils, such as hydroxylated soybean oil. These polyurethanes have different valuable properties, determined by their chemical composition and cross-linking density. In this study, soy epoxy polyols with different OH contents were prepared through a one-step reaction using the method of in situ performic acid generation. Polyols with OH functionalities from 1.9 to 3.2 were reacted in bulk with different diisocyanates at a NCO/OH molar ratio of 0.8 and 60°C for 24 h. Mechanical properties of the polyurethanes were determined by dynamic mechanical thermal analysis, hardness (Shore A), and swelling measurements. Polymer networks with glass-transition temperatures (T g ) from -13 to 48°C were obtained. We observed that the higher the OH functionality of the polyols, the higher the T g and cross-linking density of the polyurethane network. The influence of diisocyanate structure (rigid or flexible chain), curing temperature, and curing reaction time on mechanical properties was also investigated.Paper no. J10956 in JAOCS 82, 365-371 (May 2005). KEY WORDS:Hydroxylated soybean oil, mechanical properties, polyurethane, soy epoxy polyol.The use of renewable resources has attracted the attention of many researchers because of their potential to replace petrochemical derivatives (1-3). Soybean oil is an inexpensive, readily available, renewable resource and provides an excellent platform for polymeric materials. Soybean oil is mainly composed of TG molecules derived from unsaturated FA such as oleic acid (22%), linoleic acid (55%), and linolenic acid (7%). Although they possess double bonds, which are the reactive sites for coatings and paints, they need to be functionalized to prepare polymers (4). Polyurethanes (PU) have been prepared from vegetable oils in natura, such as castor oil, or from polyols obtained from vegetable oils, such as corn, sunflower, and soybean oils, and show a number of excellent properties because of the hydrophobic nature of TG (5,6). To use natural oils as raw materials for PU production, multiple hydroxyl functionalities are required. Usually these are obtained by reacting epoxidized oils with low-M.W. mono-or polyfunctional alcohols or acids.Recently, Petrovic et al. (7) reported the effect of the NCO/OH molar ratio on soy-based PU network properties using a methoxylated soy polyol (OH functionality = 3.7) and 4,4′-methylenebis(phenyl isocyanate) (MDI). Glassy polymers were produced when the NCO/OH ratio was between 0.8 and 1.05. Higher cross-linking densities, glass-transition temperatures (T g ), and tensile strengths were observed as the NCO/OH ratio increased. The influence of the diisocyanate structure on the properties of these soy-based PU was also investigated (8).Guo et al. (9) reported the physical and mechanical properties of soy polyol-derived PU prepared by the hydrogenation of hydroformylated soybean oil. When the hydroformylation reaction was rhod...

The crystallinity of isotactic polypropylene (iPP), when deformed with plastic plane‐strain compression, was studied with wide‐angle X‐ray scattering (WAXS) and differential scanning calorimetry (DSC) techniques. A comparison of the obtained crystallinity data with annealed iPP samples was performed. The material used in this study was commercial iPP (weight‐average molecular weight = 117.400 g/mol; number‐average molecular weight = 17.300 g/mol). A significant decrease in the crystallinity was observed with increasing deformation pressure when the X‐ray method was employed, whereas only a small decrease was registered when the DSC method of crystallinity determination was used. However, the annealed iPP samples demonstrated a slight crystallinity increase when evaluated by both techniques. The reason for the difference between WAXS and DSC crystallinity results is discussed. This study of iPP specimens subjected to large deformation led us to the conclusion that the WAXS method provides accurate crystallinity values for the deformed material, whereas the values obtained by the DSC method do not reproduce the real crystallinity of the deformed material. This is due to the inherent heating process of the method, which causes a relaxation process and a significant change in the crystallinity of the deformed material, providing values nearer to its intrinsic equilibrium state. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 896–903, 2002

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