Group interval-controlled polymers: an example of epoxy functional polymers via step-growth thiol–yne polymerization

Abstract

Here, we successfully synthesized a series of epoxy GICPs via one-step UV-triggered thiol–yne polymerization of commercial glycidyl propargyl ether and dithiols at 0 °C..

Hetero‐Functional Polymers with Alternating Hydroxyl and Epoxy Groups Synthesized by Thiol‐yne Click (co)Polymerization

“…These results were in good agreement with the observed thiol‐yne polymerization of 1 and another alkynyl monomer ( M n = 2400 g mol −1 and PDI = 1.42) . In addition, the GPC curves were unimodal, which further confirmed that no side reactions occurred among thiol and epoxy groups and no coupling termination events were involved in the process of chain growth because of the ultrahigh chain transfer constant of thiol monomers (Scheme S2 and Figure S2, Supporting Information) …”

“…For the achieved P1 , the T d5 (thermal decomposition temperature at 5 wt% loss) was 211.5 °C, the T d (decomposing temperature) was 307.8 °C, and the T d max (maximum decomposing temperature) was 340.7 °C. The T d of the P1 was slightly higher than those (about 295 °C) of the epoxy–containing polythioethers synthesized by UV‐initiated thiol‐yne click polymerization of the alkyl‐based dithiol compounds and propargyl glycidyl ether …”

“…For the synthesis of hetero‐functional polythioether (such as P1 ), we performed UV‐triggered thiol‐yne click polymerization of commercially available 1 and propargyl glycidyl ether at 0 °C. According to the previous reports, the lower temperature could effectively suppress those undesirable additions between thiols and epoxy groups, ensuring that hydroxyl and epoxy groups are smoothly incorporated into the target products . The obtained P1 was a colorless liquid with suitable viscosity and soluble in most of the common solvents (e.g., THF, DMF, CH 2 Cl 2 , chloroform, and so on), implying its wide and promising applications.…”

“…To further gain insight into the reactivity of these epoxy and hydroxyl groups involved the P1 s, we performed the reaction of epoxy and polyether amine (D400), although the reactivity of hydroxyl and epoxy groups within polythioethers has been proved already in the previous reports, respectively . For instance, an esterification of the hydroxyl groups could be performed with acid compounds with the help of catalysts .…”

“…Recently, free radical–initiated thiol‐yne click polymerization has been also verified to be a reliable and promising avenue for the easy and scalable synthesis of sequence‐controlled materials (especially, those products with available functional groups), owing to its inherent radical‐triggered mechanism (i.e., the tolerance of functional groups) and ultrahigh chain transfer constant of thiols (>48) . For example, under the optimized condition, such customizable functional groups, including OH, N 3 , COOH, NH 2 , epoxy groups, and so on, have been intactly incorporated into the target polymers via thiol‐yne click polymerization . Among these functional groups, the hydroxyl and epoxy groups are two kinds of especially useful groups which are expected to serve as the general platform to further functionalize or modify.…”