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We report on the linear viscoelastic properties of a family of entangled linear thermoplastic nonpolar hybrid inorganic−organic polymers:  random copolymers of polystyrene (PS) and styryl-based polyhedral oligosilsesquioxane (POSS), R7(Si8O12)(C6H4CHCH2), with R = isobutyl (iBu). A series of styrene−styryl POSS random copolymers with 0, 6, 15, 30, and 50 wt % iBuPOSS were investigated. WAXS and TEM demonstrate that the iBuPOSS disperses in the polymeric matrix at a molecular level. It is observed that the iBuPOSS plays a plasticizer-like effect, yielding a monotonic decrease of the glass-transition temperature with increasing iBuPOSS content. Rheological measurements revealed that linear viscoelastic behavior of the copolymers is also profoundly influenced by the presence of iBuPOSS. The incorporation of iBuPOSS dramatically decreases the rubbery plateau modulus ( ), suggesting a strong dilation effect of isobutyl−POSS on entanglement density. Additionally, the apparent flow activation energy, obtained by fitting the Vogel−Fulcher−Tamman−Hesse equation, monotonically increases with increasing iBuPOSS content, indicating a lower sensitivity of POSS copolymers to changes of temperature. We attribute our observations to the microscopic topology of constituent polymer chains to be altered by iBuPOSS comonomers that act as compact volumetric branches. Conversely, intermolecular interactions between iBuPOSS and PS segments do not play an essential role in determining the rheological behavior.

The most commonly found fingerprints at crime scenes are latent and, thus, an efficient method for detecting latent fingerprints is very important. However, traditional developing techniques have drawbacks such as low developing sensitivity, high background interference, complicated operation, and high toxicity. To tackle this challenge, we have synthesized two kinds of rare earth fluorescent nanomaterials, including the fluoresce red-emitting YVO4:Eu nanocrystals and green-emitting LaPO4:Ce,Tb nanobelts, and then used them as fluorescent labels for the development of latent fingerprints with high sensitivity, high contrast, high selectivity, high efficiency, and low background interference, on various substrates including noninfiltrating materials, semi-infiltrating materials, and infiltrating materials.

We report the synthesis and characterization of a series of multiblock thermoplastic polyurethane hydrogels synthesized with PEG as the soft segment and incorporating an isobutyl-functionalized POSS diol (TMP POSS diol) in the hard segment. The molecular weight of PEG was systematically varied to include 10, 20, and 35 kg/mol, while the molar ratio of POSS diol (as chain extender) to PEG was varied from 3:1 to 8:1 reported for a polymer series with PEG held constant at 10 kg/mol. The diisocyanate employed for TPU polymerization was 4,4 0 -methylenebis(phenyl isocyanate) (MDI). Wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) experiments revealed that both hydrophilic soft segments (PEG) and hydrophobic hard segments (POSS) can form crystalline structures driven by microphase separation due to the thermodynamic incompatibility. Consequently, the POSS nanocrystals serve as physical cross-linking points consisting, themselves, of an inorganic-organic hybrid networks. Interestingly, the polymers swell in water to an extent well-governed by composition, with equilibrium swelling ratio increasing with PEG loading from ∼70% to ∼600%. The water diffusion in the hydrogel was found to be non-Fickian and to depend strongly on PEG crystallinity. The shear modulus of the hybrid hydrogels spanned the range 0.3 MPa < G < 4.0 MPa, a range higher than most hydrogels studied previously. The high stiffness of such thermoplastic hydrogels was found to be controlled by the POSS:PEG mole ratio and was uncorrelated with molecular weight of PEG segment. Given their thermoplastic nature in the dry state, we envision applications involving melt processing of complex shapes and coatings, followed by hydration to hydrogel form.

Bacterial cellulose (BC) has attracted increasing attention as a novel wound dressing material, but its antimicrobial activity, which is one of the critical skin-barrier functions in wound healing, is not sufficient for use in practical applications. To overcome such a deficiency, silver nanoparticles were generated and self-assembled on the surface of BC nanofibers, forming a stable and evenly distributed Ag nanoparticle coated BC nanofiber (AgNP-BC). The performance of AgNP-BC was systematically studied in terms of antibacterial activities, cytocompatibility and effects on wound healing. The results showed that AgNP-BC exhibited significant antibacterial activity against Staphylococcus aureus. Moreover, AgNP-BC allowed attachment, and growth of rat fibroblasts with low cytotoxicity emerged. Based on these advantages, AgNP-BC samples were applied in a second-degree rat wound model. Wound flora showed a significant reduction during the healing. The fresh epidermal and dermis thicknesses with AgNP-BC samples were 111 and 855 µm respectively, higher than 74 and 619 µm for BC groups and 57 and 473 µm for untreated control wounds. The results demonstrated that AgNP-BC could reduce inflammation and promote scald wound healing.