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In a systematic manner, the roles of MWNTs as filler and styrene acrylonitrile copolymer-graft-maleic anhydride (SAN-MA) as compatibilizer, individually and together, on dynamic-mechanical behavior of polycarbonate (PC)-rich/ acrylonitrile butadiene styrene terpolymer (ABS) blend were studied. The investigations were performed using small-scale mixing in a one-step procedure with a fixed MWNTs content of 0.75 wt% and a blend composition of PC/ABS = 70/30 w/w. PC/SAN blends and nanocomposites as simpler model system for PC/ABS were also studied to reveal the role of the rubbery polybutadiene (PB) fraction. It is found that the tendency of MWNTs to localize within the PC component in compatibilized PC/ABS was lower than in compatibilized PC/SAN blends. Dynamic mechanical analysis (DMA) revealed the dual role of SAN-MA as blend compatibilizer and also promoter of MWNTs migration towards PC, where SAN-MA to MWNTs weight ratio varied between 1 and 4. At the compatibilizer/MWNTs weight ratio of 1, MWNTs localized in PC component of the blends whereas increasing the compatibilizer/MWNTs ratio to 4 led to migration of MWNTs toward SAN or ABS component. In DMA studies, loss modulus normalization of the nanocomposites revealed the coexistence of mobilized and immobilized regions within the nanocomposite structure, as a result of MWNTs and compatibilizer loading., INTRODUCTION Fillers play an essential role to adjust the polymers' advantageous characteristics to reach the property balance needed for certain applications. It is expected that high aspect ratio as well [...]

Ultraviolet (UV) irradiated supramolecularpolybutadienes (PBs)containing 2-ureido-4-[1H]-pyrimidone (UPy) linkageswere examined as a simple model for curable supramolecular elastomers.Via precise control of UV exposure, the cure and the degradation ofthe vinyl groups within the PB elastomeric core were investigated.The combination of UPy binding and covalent cross-linking by UV irradiationdramatically enhanced mechanical properties of these UPy-functionalizedelastomers, yielding toughness enhancement up to ∼200×at the 5 min UV cure. UV-initiated cross-linking dominated the curingprocess up to ∼50 min exposure time. Beyond this cure time,dominant degradation of the vinyl linkages was observed. Control ofthis UV-initiated process yielded supramolecular elastomers with acovalently cross-linked phase induced by UV irradiation combined witha noncovalent UPy cross-linked phase induced by secondary hydrogenbonding interactions. Of particular note, it was determined that thepresence of UPy hydrogen-bonded aggregates accelerated the UV cross-linkingprocess during the initial stage of exposure. This observation wasattributed to microphase-separated structure of UV-irradiated supramolecularelastomer, where UPy aggregation increased the probability of interactionbetween the pendant vinyls responsible for UV cross-linking. The systematicstudy of uniaxial tensile behavior of the UV-irradiated supramolecularelastomers offers new insight into the design and architecture ofmechanically tunable supramolecular elastomers. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, we introduce a new method for preparing ultrasmall chitosan (CS)/succinyl β-cyclodextrin (SCD) nanoparticles (NPs) intended for loading bovine serum albumin (BSA) as a model protein. The proposed method is based on the complex coacervation technique followed by ionotropic gelation with tripolyphosphate. SCD, an anionic derivative of cyclodextrin, was synthesized and used in CS-based NPs to enhance the entrapment efficiency of BSA. The results show that with this approach, ultrasmall, compact, and neutralized NPs with a mean particle size near 30 nm were obtained. A high degree of protein entrapment in the NPs led to a significant improvement in the BSA release profile with a low initial burst release (ca. 3% w/v of the initially loaded BSA) and a sustained release over time. This enabled a suitable nanocarrier for long-term protein delivery (30% release over 120 h). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39648. [ABSTRACT FROM AUTHOR]