Effect of sequence structure on wetting behaviors of fluorinated methacrylate polymers based on perfluorohexylethyl methacrylate and stearyl acrylate

Copolymerization of Styrene and Pentadecylphenylmethacrylate (PDPMA): Synthesis, Characterization, Thermomechanical and Adhesion Properties

The copolymerization of styrene (St) with a bioderived monomer, pentadecylphenyl methacrylate (PDPMA), via atom transfer radical polymerization (ATRP) was studied in this work. The copolymerization reactivity ratio was calculated using the composition data obtained from ¹H NMR spectroscopy, applying Kelen-Tudos and Finemann-Ross methods. The reactivity ratio of styrene (r₁ = 0.93) and PDPMA (r₂ = 0.05) suggested random copolymerization of the two monomers with alternation. The copolymerization conversion increased with increasing PDPMA concentration of the feed, upto 70 wt % PDPMA, but decreased thereafter. The molecular weight determined by gel permeation chromatography was lower than the theoretical values and the polydispersity increased from 1.32 to 2.19, with increasing PDPMA content in the feed. The influence of styrene content on the glass transition and thermal decomposition behavior of the copolymers was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis, respectively. Morphological characterization by transmission electron microscopy (TEM) revealed a phase separated soft core-hard shell type structure. The complex viscosity and adhesion properties like peel strength and lap shear strength of the copolymer on different substrates increased with increasing styrene content.

Emerging Applications of Fluorogenic and Non-fluorogenic Bifunctional Linkers

Homo- and hetero-bifunctional linkers play vital roles in constructing a variety of functional systems, ranging from protein bioconjugates with drugs and functional agents, to surface modification of nanoparticles and living cells, and to the cyclization/dimerization of synthetic polymers and biomolecules. Conventional approaches for assaying conjugation extents typically rely on ex situ techniques, such as mass spectrometry, gel electrophoresis, and size-exclusion chromatography. If the conjugation process involving bifunctional linkers was rendered fluorogenic, then in situ monitoring, quantification, and optical tracking/visualization of relevant processes would be achieved. In this review, conventional non-fluorogenic linkers are first discussed. Then the focus is on the evolution and emerging applications of fluorogenic bifunctional linkers, which are categorized into hetero-bifunctional single-caging fluorogenic linkers, homo-bifunctional double-caging fluorogenic linkers, and hetero-bifunctional double-caging fluorogenic linkers. In addition, stimuli-cleavable bifunctional linkers designed for both conjugation and subsequent site-specific triggered release are also summarized.

Toward Achieving Highly Ordered Fluorinated Surfaces of Spin-Coated Polymer Thin Films by Optimizing the Air/Liquid Interfacial Structure of the Casting Solutions

Thin polymer films with well-assembled fluorinated groups on their surfaces are not easily achieved via spin-coating film-fabrication methods because the solution solidifies very rapidly during spin-coating, which hinders the fluorinated moieties from segregating and organizing on the film surface. In this contribution, we have proposed a comprehensive strategy toward achieving well-ordered fluorinated thin films surfaces by optimizing the molecular organization at air/liquid interface of the film-formation solutions. To validate such a route, poly(methyl methacrylate) (PMMA) end-capped with several 2-perfluorooctylethyl methacrylate (FMA) units was employed as the model polymer for investigations. The air/solution interfacial structures were optimized by systematically changing the polymer chain structures and properties of the casting solvents. It was found that the polymers that form loosely associated aggregates (e.g., FMA₁- ec-PMMA₆₅- ec-FMA₁) and a solvent with better solubility to FMA while having not too low surface tension (i.e., toluene) can combine to produce solutions with well-assembled FMA at the interfaces. By spin-coating the solutions with well-organized interfaces, an ultrathin film with perfluorinated groups that were highly oriented toward the film surface was readily achieved, exhibiting surface energies as low as 7.2 mJ/m², which is among the lowest reported so far for the spin-coated thin films, and a very high F/C ratio (i.e., 0.98).

Statistical versus block fluoropolymers in gene delivery

A statistical fluorocopolymer shows dramatically higher transfection efficiency in gene delivery than a block one.