Preparation and surface properties of the polysiloxane material modified with fluorocarbon side chains

The novel polysiloxane material modified with fluorocarbon side chains was synthesized. FTIR, FNMR were used to characterize the copolymer structure. The emulsion of the modified polysiloxane was prepared. The reflectance spectrum of the dyed polyester fabric treated with the polymer was also discussed. The effect of the modified polysiloxane on the color fastness of the dyed polyester fabric was investigated. The results show that the novel polysiloxane material modified with fluorocarbon side chains had excellent surface activity. It did not affect the shade of color and the fastnesses of the dyed fabrics and could improve the handle of fabrics. The treated fabric with the modified polysiloxane showed excellent repellency to water.     

Light-Activated Assembly of DNA Origami into Dissipative Fibrils

Hierarchical DNA nanostructures offer programmable functions at scale, but making these structures dynamic, while keeping individual components intact, is challenging. Here we show that the DNA A-motif—protonated, self-complementary poly(adenine) sequences—can propagate DNA origami into one-dimensional, micron-length fibrils. When coupled to a small molecule pH regulator, visible light can activate the hierarchical assembly of our DNA origami into dissipative fibrils. This system is recyclable and does not require DNA modification. By employing a modular and waste-free strategy to assemble and disassemble hierarchical structures built from DNA origami, we offer a facile and accessible route to developing well-defined, dynamic, and large DNA assemblies with temporal control. As a general tool, we envision that coupling the A-motif to cycles of dissipative protonation will allow the transient construction of diverse DNA nanostructures, finding broad applications in dynamic and non-equilibrium nanotechnology.     

Chloroquine chaos and COVID-19: Smart delivery perspectives through pH sensitive polymers/micelles and ZnO nanoparticles

The global pandemic of COVID-19 had a consequential impact on our lives. (Hydroxy)chloroquine, a well-known drug for treatment or prevention against malaria and chronic inflammatory conditions, was also used for COVID patients with reported potential efficacy. Although it was well tolerated, however in some cases, it produced severe side effects, including grave cardiac issues. The variable reports on the administration of (hydroxy)chloroquine in COVID19 patients led to chaos. This drug is a well-known zinc ionophore, besides possessing antiviral effects. Zinc ionophores augment the intracellular Zn²⁺ concentration by facilitating the zinc ions into the cells and subsequently impair virus replication. Zinc oxide nanoparticles (ZnO NPs) have been reported to possess antiviral activity. However, the adverse effects of both components are also reported. We discussed in depth their possible mechanism as antiviral and smart delivery perspectives through pH-sensitive polymers/ micelles and ZnO NPs.     

Syntheses,Structures, and Properties of Two Dicyanamide‐Bridged Polymers with a Schiff‐base Ligand

The dicyanamide‐bridged polymers with Schiff‐base ligand, [CoNaL(dca)]_n ( 1 ) and [Mn₂L(dca)₂]_n ( 2 ) [H₂L = bis(3‐methoxysalicylidene)benzene‐1,2‐diamine, dca = dicyanamide] were synthesized and characterized by elemental analyses, IR spectrroscopy and single‐crystal X‐ray diffraction. The solid‐state structures reveal that polymer 1 has double dca bridged loop‐like 1D chains, in which the heterodinuclear Co²⁺‐Na⁺ units (LCoNa) are bridged by dca with coordination mode μ_1,3,5. In polymer 2 , homodinuclear Mn²⁺‐Mn²⁺(LMnMn) units are linked by dca in μ_1,5‐bridging mode to form 2D planes. Magnetic susceptibility studies on 2 reveals antiferromagnetic coupling interactions between the adjacent Mn²⁺ ions in the LMnMn unit.     

Experimental investigation on the yield loci of PA66

Compression, tensile and mixed compression/shear tests were performed on PA66 by using a universal material testing machine in order to identify the experimental yield loci of PA66. For the mixed compression/shear tests, instead of using a complex loading device, SCS (shear-compression specimens) were used to generate the additional shear stresses. Then, the mechanical behavior of materials under complex stress states can be obtained for further analysis. Results show that the experimental yield loci of PA66 obtained by the test method proposed in the present paper agree well with the theoretical model based on three stresses invariant, which indicates the reliability of the test method.     

Application of the Doehlert experimental design to molecularly imprinted polymers: surface response optimization of specific template recognition as a function of the type and degree of cross-linking

We propose the use of Doehlert’s experimental design, a second-order uniform shell design, for the optimization of molecularly imprinted polymers (MIPs). We have chosen a simple model system where the influence of kind and degree of cross-linking on template recognition was studied using S-propranolol as the template. We found that Doehlert’s design allows—with very few experiments—one to screen the evolution of the binding capacity of a MIP as a function the different parameters, and thus appears to be a powerful means to screen for the best composition and synthesis method for MIPs. We believe that this chemometric tool can significantly accelerate the development of new MIPs as synthetic recognition elements, particularly in the context of a given application, and will be a versatile complement or alternative to first-order designs to fit complex processes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Solubility in compressible polymers: Beyond the regular solution theory

The age-old idea of “like dissolves like” requires a notion of “likeness” that is hard to quantify for polymers. We revisit the concepts of pure component cohesive energy density c^P and mutual cohesive energy density c₁₂ so that they can be extended to polymers. We recognize the inherent limitations of c₁₂ due to its very definition, which is based on the assumption of no volume of mixing (true for incompressible systems), one of the assumptions in the random mixing approximation (RMA); no such limitations are present in the identification of c^P. We point out that the other severe restriction on c₁₂ is the use of pure components in its definition because of which c₁₂ is not merely controlled by mutual interactions. Another quantity as a measure of mutual cohesive energy density that does not suffer from the above limitations of c₁₂ is introduced. It reduces to c₁₂ in the RMA limit. We are able to express in terms of c₁₂ and pure component c^P’s. We also revisit the concept of the internal pressure and its relationship with the conventional and the newly defined cohesive energy densities. In order to investigate volume of mixing effects, we introduce two different mixing processes in which volume of mixing remains zero. We then carry out a comprehensive reanalysis of various quantities using a recently developed recursive lattice theory that has been tested earlier and has been found to be more accurate than the conventional regular solution theory such as the Flory-Huggins theory for polymers. In the RMA limit, our recursive theory reduces to the Flory-Huggins theory or its extension for a compressible blend. Thus, it supersedes the Flory-Huggins theory. Consequently, the conclusions based on our theory are more reliable and should prove useful.     

Morphologies of diblock copolymer thin films before and after crystallization

Spin-coated thin films of about 100nm of low-molecular-weight hydrogenated poly(butadiene-b- ethyleneoxide) (PB_h-PEO) diblock copolymers have been crystallized at various constant temperatures. Crystallization has been observed in real time by light microscopy. Detailed structural information was obtained by atomic force microscopy, mainly enabled by the large viscoelastic contrast between amorphous and crystalline regions. The behavior in thin films is compared to the bulk properties of the polymer. Crystallization started from an annealed microphase separated melt where optical microscopy indicated a lamellar orientation parallel to the substrate. A small difference in the length of the crystallizable block produced significantly different crystallization behavior, both in the bulk and in thin films. For thin films of the shortest diblock copolymer (45% PEO content) and for an undercooling larger than about 10 degrees, crystallization created vertically oriented lamellae. These vertical lamellae could be preferentially aligned over several micrometers when crystallization occurred close to a three-phase contact line. Annealing at temperatures closer to the melting point or keeping the sample at room temperature for several months allowed the formation of a lamellar structure parallel to the substrate. A tentative interpretation based on kinetically caused chain folding and relaxation within the crystalline state, with implications on general aspects of polymer crystallization, is presented. Received 19 March 1999 and Received in final form 14 December 1999     

Solid-like friction of a polymer chain

We propose a simple friction model for isolated polymer chains on a solid substrate. The chains are pulled at constant velocity by one end, the other end can be trapped on the solid substrate on localised sites. We focus on the energy dissipation due to the traps. This simple model leads to nontrivial friction laws, depending on the velocity and the distance between traps. Some refinements of the model such as the effect of thermal fluctuations are also reported. Received 20 March 2000     

The Synthesis of Neodymium Complexes with Polymers Containing Thiol and Sulphoxide and Their Catalytic Activities

Introduction Polymers containing thiol and sulphoxide which have active—SH and—SO groups respectively, have wide application to biological, pharmaceutical, industrial and other chemical field and—SH and—SO groups are easy to form complexes with metals, so they have aroused an increasing interest of many authors. A large number of functional resins and corresponding metal complexes have been synthesized.