Backbone Degradable Poly(aryl acetal) Photoresist Polymers: Synthesis, Acid Sensitivity, and Extreme Ultraviolet Lithography Performance

摘要： A new class of acid labile poly(aryl acetal) polymers has been developed that can be used in photoresist formulations for next-generation microlithography techniques including extreme ultraviolet (EUV) or electron beam lithography. Example polymers have been synthesized by an optimized Suzuki polycondensation protocol. They are soluble in common photoresist solvents but are insoluble in water or aqueous bases that are used to develop positive photoresists. The structural design includes further elements that are aimed at improving photoresist resolution, stability, and etch resistance. Upon acid exposure, the acetal linkages are cleaved, and the polymers degrade into phenolic terphenyl fragments, which are readily soluble in a photoresist developer. Polymer degradation has been studied by NMR and LC-MS. Lithographic formulations have been developed and tested in line-and-space patterning experiments using EUV photolithography. Optimized resist formulations achieved 22 nm resolution with line width roughness values of 5.7 nm.

High-Performance Biobased Unsaturated Polyester Nanocomposites with Very Low Loadings of Graphene

摘要： Graphene-reinforced tung oil (TO)-based unsaturated polyester nanocomposites were prepared via in situ melt polycondensation intergrated with Diels–Alder addition. Functionalized graphene sheets derived from graphene oxide (GO) were then extracted from the obtained nanocomposites and carefully characterized. Furthermore, dispersion state of the graphene nanosheets in the cured polymer composites and ultimate properties of the resultant biobased nanocomposites were investigated. Mechanical and thermal properties of the TO-based unsaturated polyester resin (UPR) were greatly improved by the incorporation of GO. For example, at the optimal GO content (only 0.10 wt %), the obtained biobased nanocomposite showed tensile strength and modulus of 43.2 MPa and 2.62 GPa, and Tg of 105.2 ?C, which were 159%, 191%, and 49.4% higher than those of the unreinforced UPR/TO resin, respectively. Compared to neat UPR, the biobased UPR nanocomposite with 0.1 wt % of GO even demonstrated superior comprehensive properties (comparable stiffness and Tg, while better toughness and thermal stability). Therefore, the developed biobased UPR nanocomposites are very promising to be applied in structural plastics.

Ligand-Controlled DArP for n-Type and Ambipolar Mesopolymers

Synthesis and Characterization of DPP-Based Conjugated Polymers via Dehydrogenative Direct Alkenylation Polycondensation

摘要： Two π-conjugated polymers were successfully synthesized by polycondensation via dehydrogenative direct alkenylation with Pd(II) catalyst (Pd(OAc)2) without directing groups in an atom- and step-economical and eco-friendly manner. Using the Pd(OAc)2/pyridine catalytic system, C-H activation of the C-5 position on the thiophene moiety of 3,6-di(thiophen-2'-yl)diketopyrrolopyrrole derivative was regioselective and the cross-coupled products were readily formed with trans-configuration. The optical, electrochemical, and thermal properties of the synthesized polymers were studied to investigate their potential applicability to semiconducting materials.

Controlled synthesis of unsubstituted high molecular weight poly( <i>para</i> -phenylene) <i>via</i> Suzuki polycondensation-thermal aromatization methodology

摘要： Suzuki polycondensation-thermal aromatization methodology was developed as a versatile new route to structurally regular, unsubstituted high molecular weight poly(para-phenylene) (PPP). The utility of this methodology was demonstrated by synthesizing PPP from both cis- and trans-precursor prepolymers 1a-b. The structure of precursor prepolymers containing exclusively 1,4-repeating units with the hydroxyphenyl group at the chain end was determined by two-dimensional NMR spectroscopy. Pyrolysis of trans-poly(para-phenylene) precursor 1b resulted in complete aromatization to PPP containing an average of 110 phenylene units in the polymer chain. The thermal conversion of precursor polymers to polyphenylene is a straightforward process leading to pristine PPP without significant chain degradation as confirmed by solid-state NMR and TGA analysis. The characterization of PPP by solid-state NMR, UV-vis absorption, fluorescence emission and IR spectroscopy, TGA, and conductivity measurements exhibits significant features for electronic and photoelectronic application, such as broadened absorption, high thermal stability, and typical conducting properties.

Controlled gel research: the effect of ethanol for delaying the polycondensation of tetraethyl orthosilicate-dimethyldiethoxysilane

摘要： In this study, the effect of ethanol for delaying the polycondensation of silanol in the co-hydrolysis-condensation of tetraethyl orthosilicate-dimethyldiethoxysilane was first explored and demonstrated by varying the amount of ethanol under low-water content and acid-catalyzed. On the basis of this, the controllability of the sol-gel process is realized, and the calculation formula of the gel formation time is provided. The experiment shows that the storage gel time and the reaction gel time are extended from 75 h to at least 4584 h, or from 20 to 65 h with the increase of ethanol concentration, respectively. And we observed the microscopic process of solution-sol-gel transition by light transmission microscope. The sol-gel process established in this experiment gives a mechanism reference for future research.

Synthesis and properties of hyperbranched polymers for white polymer light-emitting diodes

摘要： In this work, a series of hyperbranched copolymers with fluorene-alt-carbazole as the branches, three-dimensional-structured spiro[3.3]heptane-2,6-dispirofluorene (SDF) as the core, and iridium 1-(4-bromophenyl)-isoquinoline (acetylacetone) (Ir(Brpiq)2acac) as the dimming group were synthesized by one-pot Suzuki polycondensation for white emission. All copolymers show great thermal stabilities and high hole-transporting ability due to the introduction of the carbazole unit. The hyperbranched structures for copolymers can suppress the interchain interactions efficiently, and help to form amorphous films. The fabricated polymer light-emitting devices (PLEDs) based on the above synthesized copolymers realize good white light emission, and achieve high electroluminescence (EL) performance. For example, for the optimized PLED, the maximum luminance and current efficiency reach 6210 cd m?2 and 6.30 cd A?1, respectively, indicating the synthesized hyperbranched copolymers have potential application in solution-processable white polymer light-emitting diodes.

Synthesis of molecular‐weight‐controlled polyfluorene with boronate at one end

摘要： We investigated the synthesis of poly?uorene with a pinacol boronate (PinB) moiety at one end and with controlled molecular weight by means of Suzuki–Miyaura coupling polymerization of 7-bromo-9,9-dioctyl-9H-?uoren-2-yl boronate (1) with a palladium(0) precatalyst in the presence of pinacol 4-tri?uoromethylphenylboronate (2) as a chain terminator and CsF/18-crown-6 as a base. When we used AmPhos Pd G2, which has a propensity for intramolecular catalyst transfer on a π-electron face, poly?uorene with the PinB moiety at one end and PhCF3 (derived from 2) at the other end was obtained, and the molecular weight increased in proportion to the feed ratio of [1]0/[catalyst]0, though the molecular weight distribution was broad. Since the molecular weight also linearly increased with respect to the conversion of 1 until the middle stage of polymerization, the polymerization appears to involve chain-growth polymerization through intramolecular catalyst transfer from the Pd catalyst inserted into the C Br bond of 1. The broad molecular weight distribution might be mainly due to slow initiation and slow termination with 2, rather than polymer–polymer coupling.

Impact of Precise Control over Microstructure in Thiophene–Selenophene Copolymers

摘要： Controlling the sequence of repeat units in a synthetic polymer has been a long-standing topic of interest in chemistry. As methods to regulate sequence become more sophisticated, it is critical to consider how controlling the arrangement of repeat units along the polymer backbone impacts properties. In this work, thiophene?selenophene copolymers (statistical and periodic) were compared to elucidate the impact of periodicity on electronic properties and structural organization in conjugated macromolecules. Polymers were synthesized using catalyst-transfer polycondensation (CTP) enabling control over molecular weight and dispersity. The study revealed that optical bandgaps and redox potentials of periodic and statistical copolymers varied with composition in a predictable manner, regardless of monomer ordering along the chain. While the bandgaps of the two types of copolymers were indistinguishable, X-ray scattering revealed di?erences in solid-state packing. Both types of copolymers exhibited well-de?ned morphologies, but larger π-stacking distances and more orientational disorder were evident in the statistical systems. This indicates periodicity is an attribute that should be considered when synthesizing semiconducting materials.