Indacenodipyrene Containing Small Molecules and Ladder Polymers

A series of s-indaceno[1,2,3-cd:5,6,7-c'd']dipyrene-containing small molecule and ladder polymers were prepared using a palladium catalyzed arylation reaction. Precursor polymers and their resulting ladder polymers with molecular weights up to 13 kDa were prepared. The rigid, planar materials possessed highest occupied molecular orbital (HOMO) energies of -5.39 to -5.23 eV, lowest unoccupied molecular orbitals (LUMO) energies of -2.42 eV to -2.98 eV, and optical gaps of 1.68 to 2.03 eV. Organic field effect transistors were prepared with derivatives giving hole mobilities up to 2.5 X 10-5 cm2V-1s-1.

Highly stretchable or extremely soft silicone elastomers? One reaction to make them all - from easily available materials!

An easy curing reaction to prepare silicone elastomers is reported, in which a platinum catalyzed reaction of telechelic/multi-hydrosilane (Si-H) functional polydimethylsiloxane (PDMS) in the presence of oxygen and water leads to slow crosslinking. This curing chemistry allows versatile tailoring of elastomer properties, which exceed their intrinsic limitations. Both highly stretchable silicone elastomers and extremely soft silicone elastomers are prepared by creating highly entangled elastomers and bottle-brush elastomers from commercial precursor polymers, respectively. The highly stretchable elastomers can be uniaxially stretched to a maximum strain of 2800% and their areas can be biaxially extended 180-fold. The extremely soft silicone elastomers exhibit shear moduli of 1.2-7.4 kPa, depending on composition, values that are comparable to hydrogels and human soft tissues. The reported curing chemistry can be used to prepare a range of silicone elastomers with carefully tailored mechanical properties.

Synthesis of Single-Handed Helical Spiro-Conjugated Ladder Polymers through Quantitative and Chemoselective Cyclizations

<div>We report the unprecedented synthesis of one-handed helical spiro-conjugated ladder polymers with well-defined primary and secondary structures, in which the spiro-linked</div><div>dibenzo[a,h]anthracene fluorophores are arranged in a one-handed twisting direction, through quantitative and chemoselective acidpromoted intramolecular cyclizations of random-coil precursor polymers composed of chiral 1,1’-spirobiindane and achiral bis[2-(4-alkoxyphenyl)ethynyl]phenylene units. Intense circular dichroism (CD) and circularly polarized luminescence (CPL) were observed, whereas the precursor polymers exhibited negligible CD and CPL activities. The introduction of 2,6-dimethyl substituents on the 4- alkoxyphenylethynyl pendants is of key importance for this simple,</div><div>quantitative, and chemoselective cyclization. This strategy is applicable to the defect-free precise synthesis of other varieties of fully p-conjugated molecules and coplanar ladder polymers that have not been achieved before.</div>

Synthesis of Single-Handed Helical Spiro-Conjugated Ladder Polymers through Quantitative and Chemoselective Cyclizations

<div>We report the unprecedented synthesis of one-handed helical spiro-conjugated ladder polymers with well-defined primary and secondary structures, in which the spiro-linked</div><div>dibenzo[a,h]anthracene fluorophores are arranged in a one-handed twisting direction, through quantitative and chemoselective acidpromoted intramolecular cyclizations of random-coil precursor polymers composed of chiral 1,1’-spirobiindane and achiral bis[2-(4-alkoxyphenyl)ethynyl]phenylene units. Intense circular dichroism (CD) and circularly polarized luminescence (CPL) were observed, whereas the precursor polymers exhibited negligible CD and CPL activities. The introduction of 2,6-dimethyl substituents on the 4- alkoxyphenylethynyl pendants is of key importance for this simple,</div><div>quantitative, and chemoselective cyclization. This strategy is applicable to the defect-free precise synthesis of other varieties of fully p-conjugated molecules and coplanar ladder polymers that have not been achieved before.</div>

An In-Depth Analysis Approach Enabling Precision Single Chain Nanoparticle Design

The formation of single chain nanoparticles (SCNPs) is typically characterized by a shift towards higher elution volumes in SEC due to size decrease upon folding. However, a step-change in SCNP analysis is required for understanding of the nature of intramolecular SCNP folding. Herein, we exploit a unique combination of SANS, 19F NMR spectroscopy, and multidetection SEC to generate a systematic view of the folded morphology of poly(butyl acrylate) based-SCNPs as a function of their reactive group density and molar mass. In addition to detailed morphological insights, we establish that the primary factor dictating the compaction of SCNPs is their reactive group density, which is ineffective below 5 mol%, reaching maximum compaction close to 30 mol%. Above 20 kDa the molar mass of the precursor polymers has a minor impact on how an SCNP compacts.

An In-Depth Analysis Approach Enabling Precision Single Chain Nanoparticle Design

The formation of single chain nanoparticles (SCNPs) is typically characterized by a shift towards higher elution volumes in SEC due to size decrease upon folding. However, a step-change in SCNP analysis is required for understanding of the nature of intramolecular SCNP folding. Herein, we exploit a unique combination of SANS, 19F NMR spectroscopy, and multidetection SEC to generate a systematic view of the folded morphology of poly(butyl acrylate) based-SCNPs as a function of their reactive group density and molar mass. In addition to detailed morphological insights, we establish that the primary factor dictating the compaction of SCNPs is their reactive group density, which is ineffective below 5 mol%, reaching maximum compaction close to 30 mol%. Above 20 kDa the molar mass of the precursor polymers has a minor impact on how an SCNP compacts.

Analysis of Terpolymerization Systems for the Development of Carbon Fiber Precursors of PAN

The thermal stabilization of polyacrylonitrile fibers (FPAN) is one of the most important steps in the production of carbon fibers (CFs). In this paper, new precursor polymers from PAN have been synthesized with different chemical characteristics using a solution polymerization, and FPAN was obtained using an unconventional wet spinning system in the drying and collapsing steps. The effect of different operation conditions, comonomers, and termonomers on the properties of precursor polymers, polymerization reactions, mechanical properties, structural characteristics, and stabilization of the FPAN was studied and analyzed. FTIR and optical microscopy were used to analyze structural changes of FPAN in the thermal stabilization. The impact of the chemical composition of the precursor polymers on the physicochemical characteristics of FPAN and their behavior in the thermal stabilization process were evaluated. In particular, itaconic acid termonomer improved the tensile strength of the fibers from 8.07 to 16.87 cN/dtex, and the extent stabilization increased from 1.81 to 4.6. FTIR indicated that the reaction of stabilization of the terpolymer developed was initiated at a lower temperature compared to that of a commercial precursor polymer.