Combining the concept of "flexible spacer" which can bring liquid crystalline (LC) properties to the side-chains and the side-group "jacketing" effect which can result in main-chain with rod-like conformation, we have synthesized a new combined main-chain/side-chain LC polymer based on radical polymerization, poly(2,5-bis{[6-(4-methoxy-4 0oxy-azobenzene)hexyl]oxycarbonyl}styrene) (denoted as P 1 ) with two azobenzene groups per repeating unit. The chemical structures of P 1 and the corresponding monomer were characterized using various techniques with satisfactory analysis data. The phase structures and transitions of P 1 were investigated using differential scanning calorimetry, polarized optical microscope, and one-and two-dimensional (1D and 2D) wide-angle X-ray diffraction. We identify that P 1 can form a hierarchically ordered structure with double orderings on both the nanometer and subnanometer length scales. Most likely, the thick main-chains of P 1 obtained by "jacketing" the central rigid portion of terephthalate side-chain to the polyethylene backbone construct a 2D centered rectangular scaffold, which is stable until the sample becomes completely isotropic. The packing of side-chains inside the main-chain scaffold undergoes the transitions of smectic B-(SmB-) like T smecitc A (SmA)-like T isotropic. The confinement arising from the scaffold induces the SmB-like packing and enhances the stability of SmA-like structure. The hierarchically ordered structure of P 1 renders a biaxial orientation with the side-chains perpendicular to the main-chains. We compared P 1 with an end-on side-chain LC polymer of poly(4-{[6-(4-methoxy-4 0 -oxy-azobenzene)hexyl]oxycarbonyl}styrene) (denoted as P 2 ). P 2 bearing one mesogenic group per repeating unit forms a monolayer SmA phase, with the transition temperature much lower than that of P 1 . Upon UV irradiation, in contrast to that P 2 will become isotropic, P 1 can still exhibit LC behavior after the azobenzene groups adopt cis conformation.
A series of water‐soluble semirigid thermoresponsive polymers with well‐defined molecular weights based on mesogen‐jacketed liquid crystal polymers (MJLCPs), poly[bis(N‐hydroxyisopropyl pyrrolidone) 2‐vinylterephthalate] (PHIPPVTA) have been synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Dynamic light scattering (DLS) revealed that the novel monomer and polymers have thermoresponsive properties with cloud point in the range between 10 and 90 °C. The cloud point was increased by 56.2 °C when the polymer molecular weight increased from 0.47 × 104 g mol−1 to 3.69 × 104 g mol−1. In addition, the cloud point of PHIPPVTA was decreased by 18.8 °C with the increase of polymer concentration from 5 to 10 mg mL−1. A slight increase (0.1–3.5 °C) of cloud point has been observed after knocking off the end‐groups of PHIPPVTA. Moreover, the cloud point of polymer increased with increasing of its molecular weight with or without the trithiocarbonate end‐groups, which showed the opposite trend comparing with other thermoresponsive polymers with flexible backbones. These polymers show a dramatic solvent isotopic effect that the cloud point in D2O was lower than in H2O. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
A novel double liquid crystalline (LC) block copolymer (BCP) composed of poly[ω-(4′-methoxybiphenyl-4-yloxy)hexyl methacrylate] (PMBHMA) and poly{2,5-bis[(4-meth-oxyphenyl)oxycarbonyl]styrene} (PMPCS) was designed and successfully synthesized by reversible addition−fragmentation chain transfer (RAFT) polymerization. Whereas PMBHMA is a conventional side-chain LC (SCLC) polymer, PMPCS is a typical mesogen-jacketed LC polymer, which can serve as rod after it forms columnar LC (Φ) phase. Therefore, the PMBHMA-b-PMPCS is an SCLC−rod BCP. The phase structures and transitions of the PMBHMA-b-PMPCS synthesized with a PMPCS volume fraction of ∼49% were investigated using various techniques including thermal analysis and X-ray scattering and diffraction methods. A microphase-separated lamellar morphology was identified for this SCLC−rod sample. The Φ phase of the PMPCS block with the rod direction perpendicular to the interface remained unchanged and impacted the LC transitions of PMBHMA blocks greatly. We found that the smectic A phase of the PMBHMA disappeared, and meanwhile, its nematic phase got stabilized over a wide temperature range. At low temperatures, small smectic E domains with homogeneous orientation formed in the PMBHMA block domains. Our work demonstrates that the confinement imposed by the rod block and dimension commensurability of the ordered structures are indeed crucial for SCLC−rod BCPs.
Protein glycosylation plays a critical role in post-translational modifications of proteins in the organism and is involved in many diseases. However, the huge challenge for glycoproteins to be highly specific isolated and adsorbed from complicated biological samples results from their low abundance and interference. In this work, a novel dual-functionalized magnetic metal-organic frameworks nanoparticle for selective enrichment of glycoproteins was synthesized for the first time. Due to the abundant amino groups and grafted phenylboronic acid, the proposed nanoparticles have the dual properties of hydrophilicity and boronic acid affinity. The obtained nanoparticles show high binding capacities toward glycoproteins under physiological state (pH 7.4) such as ovalbumin (327.28 mg/g), transferrin (241.17 mg/g), horseradish peroxidase (530.79 mg/g). Furthermore, the nanoparticles still have excellent enrichment performance after being used six times repeatedly. More importantly, the prepared nanoparticles also have great potential applications in the adsorption of glycoproteins from complex biological specimens.
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