Solvent-Free Synthesis of Layered Polymer Crystals

Abstract

ABSTRACT:A new solvent-free synthetic process of layered polymer crystals as novel organic intercalation materials from (Z, Z)-muconic acid is described. This process includes the monomer synthesis, topochemical polymerization, transformation to poly(muconic acid), and intercalation. Alkylammonium muconate monomers were prepared by grinding muconic acid and the corresponding alkylamines in a ceramic mortar without any solvent. Topochemical polymerization of the alkylammonium muconates in the crystalline state was carried out under UV irradiation with a high-pressure mercury lamp or sunlight. Transformation from poly(alkylammonium muconate) to poly(muconic acid) was achieved by thermolysis at 250• C under reduced pressure with a maintenance of their crystallinity. Intercalation of alkylamines into the polymer crystals proceeded by grinding poly(muconic acid) and alkylamine similar to the monomer synthesis. This process is a new type of polymer synthesis using green and sustainable materials and reactions as the solvent-free system. KEY WORDS Topochemical Polymerization / Polymer Crystal / Intercalation / Solvent-Free Organic Reaction / Green Chemistry / Muconic Acid / Intercalation is an interesting phenomenon that guest molecules are reversibly inserted into a layered host compound with the maintenance of their layered structure. 1 While many kinds of organic and inorganic guest compounds have already been reported, host compounds are always inorganic materials such as graphite, clay, and metal oxides. 2-6 Recently, we have reported that poly(muconic acid) crystals act as a novel organic intercalation host. 7,8 The polymer crystals are obtained from the topochemical polymerization of alkylammonium muconates and the subsequent hydrolysis. 9 All the topochemically polymerizable monomer crystals of alkylammonium salts have a layered structure; the layer of muconate dianions is sandwiched with the layers of alkylammonium cations. 9-11 The layered structure is preserved during the polymerization and the subsequent transformation. The intercalation system is important to synthesize functional polymer crystals that cannot be obtained by the direct topochemical polymerization in the crystalline state.In our previous study, the intercalation of alkylamine into the poly(muconic acid) crystals was carried out heterogeneously with a polar organic solvent as the dispersant. Reaction behaviors depended on the kind of used the amine and the dispersant. For the intercalation of n-alkylamine, a high conversion was achieved in the reaction dispersed in methanol. 7 In contrast, the polymer crystals dissolved in methanol during an attempt to intercalate branched alkylamine. Insoluble alkylamines are not intercalated in a methanol dispersion system.

Polymer Structure Control Based on Crystal Engineering for Materials Design

“…152 This is performed in a simple and convenient procedure by grinding the PMA crystals in the presence of a neat amine in a mortar without any solvent. The intercalation proceeded regardless of the kind of the alkylamine used.…”

Intercalation of Mono‐ and Difunctional Azobenzenes as Photoresponsible Guest Molecules into Poly(muconic acid) Host Crystals

“…The results for the intercalation of various mono‐ and diamino‐functionalized azobenzene derivatives into the host PMA crystals are summarized in Table 2. We first attempted the intercalation of MAB‐0 as a commercially available azobenzene using a dispersed system in methanol and a grinding method in the solid state,41 but MAB‐0 was not incorporated into the PMA due to the low basicity of the guest aniline (p K a = 4.6 for aniline). It was also confirmed that aniline was not intercalated into the PMA.…”

Reactions of 1,3-Diene Compounds in the Crystalline State

“…Some mechanical and structural properties have already been revealed with well-defined and highly or partly crystalline polymers [108][109][110][111].A totally solvent-free system for the synthesis of layered polymer crystals was also reported [112].…”