Topochemical Polymerization Of Diacetylenes Research Articles

Intrinsically Porous Polydiacetylene from a Functionalized Bowl-Shaped Hexaphenoxycyclotriphosphazene Derivative

Intrinsic porosity in polymeric materials arises from the formation of a continuous network of interconnected voids and is a direct consequence of the shape and rigidity of the molecular building blocks. To obtain well-defined pores with narrow size distributions, the polymerization of rigid and sterically hindered monomers must not interfere with the pore formation and should avoid the use of additives that may occupy voids. Polydiacetylenes can be generated by the topochemical polymerization of diacetylene-bearing molecules favorably arranged in crystals, gels, thin films, or vesicles. Polydiacetylene formation in amorphous materials has been sparsely studied because higher-order self-assembled structures are assumed to be required for the topochemical polymerization of 1,3-butadiyne to occur. In this study, a bulky hexachlorocyclotriphosphazene core (N3P3Cl6) was functionalized with six diacetylene-containing alkyl chains and successfully converted to an intrinsically porous multifunctional polydiacetylene. The successful formation of the polydiacetylene was confirmed by Raman spectroscopy, and the porous structure of the resulting materials was verified by X-ray diffraction and Brunauer–Emmett–Teller surface area measurements. This investigation revealed a significant change in the porous structure after polymerization, leading to a 5-fold increase in specific surface area. Overall, the topochemical polymerization of diacetylenes is a promising strategy for the preparation of functional materials, which is shown to be compatible with rather amorphous phases of bulky molecules. The results obtained from this investigation give access to a range of porous polydiacetylene materials for potential applications in organic electronics, gas adsorption, and other related fields.

Topochemical polymerization of diacetylenes

Since the discovery of conducting polymers, they have received considerable attention both from academic and industry due to their attractive advantages of light weight, low cost, and easy processing, which make them demonstrate a wide range of applications. Over the past decades, significant advances have been achieved in this field with the development of high performance polymeric semiconductors and device fabrication techniques. However, there are still many scientific questions existing in this field, such as the unclear charge transport physics in conjugated polymers due to disordered molecular structures in the widely investigated films. Compared to thin films, single crystals possess long-range molecular order, no grain boundaries and no defects, which are seen as the best candidates for revealing the intrinsic charge transport of materials. However, it has been a big challenge for the crystallization of polymers directly from solution, and even is elusive for the conjugated polymers due to their intrinsic electron-rich conjugated backbone structures. Topochemical polymerization where under a certain reaction condition, the preorganized monomer crystals could be directly changed to their corresponding polymer crystals with a minimum amount of atomic and molecular movement, that is realizing the single-crystal-to-single-crystal transformation would provide us a promising solution. Compared to traditional solution process, with this method, we can possibly realize two goals: (1) the controllable synthesis because the first crystal growth process is from the monomer molecules; (2) the possible obtainment of higher molecule-weight polymer chains because we do not need consider their solubility problem like that from solution synthesis.

Strategies for the Preparation of Layered Polydiacetylenes

We previously reported that ureylene and oxalamide dicarboxylic acids self-assemble to form layered supramolecular structures. Since the intermolecular repeat distances within these ureylene and oxalamide layers were similar to that distance necessary for the topochemical polymerization of diacetylenes, we envisioned using both the ureylene and oxalamide functionality to orient diacetylene for topochemical polymerization. Our approach uses host-guest chemistry to layer the diacetylene functionality. This strategy proved successful when the urea functionality was used to orient diacetylenes. We now report on the successful use of the oxalamide functionality to orient diacetylenes for topochemical polymerization.

Theoretical Investigation on the Topochemical Polymerization of Diacetylenes

Abstract The solid-state polymerization of diacetylenes (MDA-PBT-PDA) is studied with a concerted reaction model and the calculation method of EHMO-ASED and EHCO-ASED, where MDA = crystalline molecular diacetylenes, PBT = polybutatrienes, and PDA = polydiacetylenes. As the reaction goes on, the symmetry of frontier orbitals inverts at state PBT, HOCO from C 2-antisymmetry to C 2-symmetry and LUCO from C 2-symmetry to C 2-antisymmetry, which means completion of the 1,4-addition. Two necessary conditions must be satisfied for the reaction to take place: 1) the geometric parameters must undergo a series of concerted changes to make the conformation suitable for the intermolecular 1,4-addition, which should overcome an energy barrier Eb ; 2) the symmetry match between the frontier crystal orbitals of the reactant and the product must be satisfied-electrons of the reactant should be excited from HOCO (C 2-antisymmetry) into LUCO (C 2-symmetry), which faces an energy gap E g. At state MDA, there is E g(MDA) ≈ 5...

Topochemical Reactions in Langmuir-Blodgett Multilayers

Abstract The topochemical polymerization of diacetylenes and.the dimerization of cinnamic acid derivatives have been studied in Langmuir-Blodgett-multilayers. The resulting polymer films are of controlled thickness and morphology and exhibit excellent stability. Structure, morphology and phase changes occuring in monomer and polymer films have been investigated using spectroscopic methods, electron and x-ray diffraction. Possible applications of the polymer films are discussed.

Introductory lecture: solid-state polymerization

Two different approaches to the problem of how to synthesize macroscopic and nearly defect-free single crystals of polymers are reviewed with the aim of clarifying the underlying physico-chemical principles and of defining the scope of such methods for the further development of the solid-state physics of polymers. The two methods are (i) the topochemical polymerization of diacetylenes and (ii) the simultaneous polymerization and crystallization of trioxane close to the ceiling-equilibrium. Polymers with a backbone of conjugated multiple carbon bonds are formed in the first case via a reaction which proceeds without nucleation phenomena such that the single-crystal nature of a polymerizing crystal is always retained up to quantitative conversion.Single crystals of poly(oxymethylene) grow in the second case following a BCF-type of crystal growth, the growth features being controlled by the nature and the concentration of the catalyst employed.