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Relevant academic research and scientific papers

Cationic surfactant prepared from waste polyester and preparation method thereof

The invention discloses a cationic surfactant prepared from waste polyester, and a preparation method thereof. According to the preparation method, a mixed catalyst is adopted to realize high efficiency alcoholysis of waste polyester, halogenation reaction is adopted, and the novel cationic surfactant with high activity and high bactericidal activity is prepared via reaction of waste polyester with alkyl morpholine. The preparation method comprises following steps: waste polyester alcoholysis, preparation of a halogenation intermediate, and preparation of the cationic surfactant, wherein BHEXand a long-chain alkyl morpholine (RNA) at a molar ratio of 1:2-1:2.5 are introduced into a reactor containing excess acetone, are heated to 50 to 57 DEG C for 1 to 5h of reaction, an obtained productis subjected to underpressure distillation at 25 to 30 DEG C to remove acetone so as to obtain a finished product. The cationic surfactant is stable in product performance, high in yield, is convenient for industrialized production, is capable of realizing effective recovery and recycling of waste polyester fiber, and is high in application value.

Segmented block copolyesters using click chemistry

Copper(I) catalyzed azide-alkyne 1,3-Huisgen cycloaddition reaction afforded the synthesis of triazole-containing polyesters and segmented block copolyesters at moderate temperatures. Triazole-containing homopolyesters exhibited significantly increased (～40 °C) glass transition temperatures (Tg) relative to high temperature, melt synthesis of polyesters with analogous structures. Quantitative synthesis of azido-terminated poly(propylene glycol) (PPG) allowed for the preparation of segmented polyesters, which exhibited increased solubility and mechanical ductility relative to triazole-containing homopolyesters. Differential scanning calorimetry demonstrated a soft segment (SS) Tg near -60 °C for the segmented polyesters, consistent with microphase separation. Tensile testing revealed Young's moduli ranging from 7 to 133 MPa as a function of hard segment (HS) content, and stress at break values approached 10 MPa for 50 wt % HS segmented click polyesters. Dynamic mechanical analysis demonstrated an increased rubbery plateau modulus with increased HS content, and the Tg's of both the SS and HS did not vary with composition, confirming microphase separation. Atomic force microscopy also indicated microphase separated and semicrystalline morphologies for the segmented click polyesters. This is the first report detailing the preparation of segmented copolyesters using click chemistry for the formation of ductile membranes with excellent thermomechanical response.

One-pot synthesis of ω-bromoesters from aromatic aldehydes and diols using pyridinium hydrobromide perbromide

A simple and efficient one-pot procedure has been developed for the synthesis of ω-bromoesters from aromatic aldehydes and diols in the presence of pyridinium hydrobromide perbromide (PHPB) and triethoxymethane in which aldehyde reacts first with diol and the product, cyclic acetal, reacts with PHPB to give the final product, ω-bromoesters.

A new synthetic method for haloalkyl carboxylic esters from the radical ring cleavage of cyclic acetals with haloform

A one-pot reaction of cyclic acetals with haloform catalyzed by AIBN(2,2'-azobisisobutyronitrile) provides a novel convenient way to prepare directly haloalkyl carboxylic esters in good yields.