Solid polymer electrolytes (SPEs) are desirable in lithium metal batteries (LMBs) since they are nonflammable and show excellent lithium dendrite growth resistance. However, fabricating high performance polymer LMBs is still a grand challenge because of the complex battery system. In this work, a series of tailor-designed hybrid SPEs were used to prepare LMBs with a LiFePO 4 -based cathode. High performance LMBs with both excellent rate capability and long cycle life were obtained at 60 and 90 C. The well-controlled network structure in this series of hybrid SPEs offers a model system to study the relationship between the SPE properties and the LMB performance. We show that the cycle life of the polymer LMBs is closely correlated with the SPE|Li interface ionic conductivity, underscoring the importance of the solid electrolyte interface in LMB operation. LMB performance was further correlated with the molecular network structure.We anticipate that results from this study will shed light on designing SPEs for high performance LMB applications.

The ideal bone scaffold harnesses the body's ability to regenerate bone in critical size defects. A potential strategy to design the ideal bone scaffold is to mimic the natural structure of bone at the molecular level. The orientation and spatial distribution of nanocrystals in the organic matrix are two important and distinctive structural characteristics associated with natural bone. There has yet to be a synthetic system or scaffold that is able to control both the spatial distribution and orientation of the hydroxyapatite crystalline structure. To mimic the unique hybrid structure of natural bone using synthetic materials, there have been a number of reported approaches to control the mineral nanocrystal orientation on synthetic scaffolds. However, the spatial distribution of minerals is challenging to reproduce in a biomimetic manner. Herein we report using block copolymer-decorated polymer nanofibers to achieve biomineralized fibrils with precise control of both mineral crystal orientation and spatial distribution. We show that the crystallization of poly(caprolactone)-b-poly(acrylic acid) block copolymer on poly(caprolactone) nanofibers resulted in a unique shish kebab structure that significantly enhances the mechanical properties of the nanofibers, and is cytocompatible to L-929 mouse fibroblast cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1786-1798, 2017.

Electrospinning of nanofiber is of growing interest especially in bone tissue engineering because of its similar fibrous properties to the extracellular matrix. To this end, we have fabricated polycaprolactone (PCL) nanofiber shish kebab (NFSK) templates. The novelty of this work is the ability to control the mineral orientation and spatial location on the nanofiber, mimicking natural collagen fibers. However, NFSK templates have properties that need to be investigated in terms of cellular response including fiber alignment and crystallization. In this study, MC3T3 E1 preosteoblast cells were seeded onto the templates to determine the effect of both fiber orientation and kebab size on the cell metabolic activity. PCL was electrospun to form aligned and randomly oriented nanofibers, which were then crystallized in a PCL solution in pentyl acetate for 15 and 60 min, resulting in the formation of homopolymer PCL NFSK templates. We evaluated the cell proliferation and alkaline phosphatase activity of MC3T3 E1 cells after 3, 7, and 14 days in coculture. Aligned nanofiber and polymer crystallization both significantly increased the cell proliferation and alkaline phosphatase activity at each time point. The aligned nanofibers and polymer crystallization resulted in the highest metabolic activities of the cells compared to the randomly oriented fibers and noncrystallized controls.

To date the scrolled morphology of γ-phase poly­(vinylidene fluoride) (PVDF) has been witnessed via high temperature melt crystallization of crystalline thin films and through imaging of chemical etched PVDF bulk films. Here we show the first growth and characterization of free-standing γ-phase PVDF scrolls via solution crystallization. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy have been used to characterize and to further understand the fundamental preferred crystalline habit of the γ-phase of PVDF.

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