Novel amphiphilic comb‐dendronized diblock copolymers composed of hydrophobic Percec‐type dendronized polystyrene block and hydrophilic comb‐like poly(ethylene oxide) grafted polymethacrylate P(PEOMA) block were designed and synthesized via two steps of atom transfer radical polymerization (ATRP). The comb‐like P(PEOMA) prepared by ATRP of macromonomers (PEOMA) with two different molecular weights (Mn = 300 and 475) were used to initiate the sequent ATRP of dendritic styrene macromonomer (DS). The molecular weights and compositions of the obtained block copolymers were determined by 1H NMR analysis. The copolymers with relatively narrow polydispersities (1.27–1.38) were thus obtained. The bulk properties of comb‐dendronized block copolymers were studied by using differential scanning calorimetry, polarized optical microscopy and wide‐angle X‐ray diffraction (WAXD). Similar to dendronized homopolymers, the block copolymers exhibited hexagonal columnar liquid‐crystalline phase structure. By using such amphiphilic comb‐dendronized block copolymers as building blocks, the rich self‐assembly morphologies, such as twisted string, vesicle, and large compound micelle (LCM), were obtained in a mixture of CH3OH and THF. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4205–4217, 2008

Self-assembly behaviors of a series of hydrophobic side-chain liquid crystalline (LC) polyacetylenes, namely, poly(5-{[(4‘-alkoxy-4-biphenylyl)carbonyl]oxy}-1-pentyne)s [P-3,m (m = 5, 7, 9)], were studied in dilute solutions. The assembly was induced by tuning the solvent property to be selective for the alkyl tails on the side chains, with the processes characterized by turbidity, dynamic light scattering, 1H NMR, and excitation fluorescence anisotropy measurements. The morphology and structure of the P-3,m aggregates formed in the solutions were investigated using atomic force microscopy and wide-angle X-ray diffraction. The experimental results indicate that the P-3,m polymers can form monolayer lamellae in selective solvents. In the lamella, the P-3,m molecules are sheetlike and pack parallel to each other with their backbones located in the lamellar center and their alkyl tails covering the top and bottom lamellar surfaces. The lamellar thickness is largely determined by the width of the molecular sheet. When the solvent becomes selective for the tails, the P-3,m chains may undergo shape stiffening to become more sheetlike.

The properties of the polyolefins blends depend not only on composition but also on morphology.

Tibetan pigs show a widespread distribution in plateau environments and exhibit striking physiological and phenotypic differences from others pigs for adaptation to hypoxic conditions. However, the regulation of mRNAs and metabolites as well as their functions in the alveolar type II epithelial (ATII) cells of Tibetan pigs remain undefined. Herein, we carried out integrated metabolomic and transcriptomic profiling of ATII cells between Tibetan pigs and Landrace pigs across environments with different oxygen levels to delineate their signature pathways. We observed that the differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs) profiles displayed marked synergy of hypoxia-related signature pathways in either Tibetan pigs or Landrace pigs. A total of 1,470 DEGs shared between normoxic (TN, ATII cells of Tibetan pigs were cultured under 21% O2; LN, ATII cells of Landrace pigs were cultured under 21% O2) and hypoxic (TL, ATII cells of Tibetan pigs were cultured under 2% O2; LL, ATII cells of Landrace pigs were cultured under 2% O2) groups and 240 DAMs were identified. Functional enrichment assessment indicated that the hypoxia-related genes and metabolites were primarily involved in glycolysis and aldosterone synthesis and secretion. We subsequently constructed an interaction network of mRNAs and metabolites related to hypoxia, such as guanosine-3′, 5′-cyclic monophosphate, Gly-Tyr, and phenylacetylglycine. These results indicated that mitogen-activated protein kinase (MAPK) signaling, aldosterone synthesis and secretion, and differences in the regulation of MCM and adenosine may play vital roles in the better adaptation of Tibetan pigs to hypoxic environments relative to Landrace pigs. This work provides a new perspective and enhances our understanding of mRNAs and metabolites that are activated in response to hypoxia in the ATII cells of Tibetan pigs.

Summary: High‐impact isotactic polypropylene (hiPP) is a multiphase material and hiPP is susceptible to stress‐whitening (or blushing) when exposed to impact, tension etc. Stress‐whitening will influence the quality of the products. The object of this work is to find the factors influencing the resistance of stress whitening. Five reactor‐alloy hiPP samples were used. Stress whitening was characterized by Gardner‐type impact apparatus. Automated PP viscometer and xylence solubles analyzer (CrystEX), tapping mode atomic force microscopy (TMAFM), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) were used to characterize the samples. The stress‐whitening was found to be related with the following factors: 1.particle size of the dispersion phase (rubber phase), 2.composition of the dispersion phase, 3.crystallization in in the dispersion phase, 4.crystalline form of the matrix (iPP).

No abstract

No abstract

No abstract