The synthetic routes and materials properties of polypropylene/montmorillonite nanocomposites are reviewed. The nanocomposite formation is achieved in two ways: either by using functionalized polypropylenes and common organo-montmorillonites, or by using neat/ unmodified polypropylene and a semi-fluorinated organic modification for the silicates. All the hybrids can be formed by solventless melt-intercalation or extrusion, and the resulting polymer/inorganic structures are characterized by a coexistence of intercalated and exfoliated montmorillonite layers. Small additionsstypically less than 6 wt %sof these nanoscale inorganic fillers promote concurrently several of the polypropylene materials properties, including improved tensile characteristics, higher heat deflection temperature, retained optical clarity, high barrier properties, better scratch resistance, and increased flame retardancy.

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This paper discusses a new family of ferroelectric polymorphic fluoroterpolymers comprosed of vinylidene difluoride (VDF), trifluoroethylene (TrFE), and a chloro-containing third monomer, such as chlorodifluoroethylene (CDFE), and chlorotrifluoroethylene (CTFE), which feature relatively narrow molecular weight and composition distributions. The terpolymers were prepared by a bulk reaction process with a low temperature free radical initiator, i.e., the oxidation adducts of trialkylborane and oxygen. The slightly bulky chlorine atom serves as a kink in the polymer chain, which spontaneously alters the chain conformation and crystalline structure. Compared to the corresponding VDF/TrFE copolymer (>20 mol % of TrFE), the slowly increasing chlorine content (<8 mol % of termonomer) gradually changes the all-trans (t m >4) chain conformation (β-phase) to tttg+tttg- conformation (γ-phase) without significant reduction of overall crystallinity. The Curie (ferroelectric−paraelectric) phase transition temperature between the mixed ferroelectric β- and γ-phases and paraelectric α-phase (tg+tg- conformation) also gradually reduced to near ambient temperature with very small activation energy. Consequently, the terpolymers show high dielectric constant (>70), slim polarization hysteresis, and large electrostrictive response (>4%) at ambient temperature and exhibit common ferroelectric relaxor behaviors with a broad dielectric peak that shifted toward higher temperatures as the frequency increased.

Polyolefins, including polyethylene (PE) and polypropylene (PP), represent more than half of commercial polymers produced in the world. They are known to be costeffective and good performing materials used in a broad range of commodity applications that influence our everyday lives. On the other hand, less attention has been paid to their specialty applications, commonly requiring the material to have multiple performance functions. The limitations and shortcomings of polyolefins have stemmed from lack of functionality and structure diversity, which are compounded with the long-standing challenges in the chemical modification (functionalization) of polyolefins. In the past two decades, in conjunction with advances in metallocene catalysis, a new method based on the "reactive" polyolefin approach has emerged, which affords a new class of functional polyolefins with high molecular weight and well-controlled molecular structures that have functional groups located at chain ends, side chains, and block/graft segments. In addition to forming distinctive multiple phase morphology with shape hydrophobic−hydrophilic microphase separation and surface properties, some functional polyolefins with flexible polar (or ionic) groups offer excellent mobility for polarization, ion conductivity, etc. They present potentials for polyolefins in high-value, specialty applications. In this paper, I will cover three energy-related areas, including polymer film capacitors for electric energy storage, ion exchange membranes for hydrogen energy, and oil superabsorbent polymers for oil spill recovery, to discuss the effects of new polyolefin structures on their performances and the future perspectives. The objective is to provide examples that reveal underlying benefits of this new class of high-performance, cost-effective functional polyolefin materials and hopefully inspire more researchers to explore their applications.

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