Synthesis and characterization of functional polyethylene with regularly distributed thioester pendants via ring‐opening metathesis polymerization

Abstract

Four kinds of functional polyethylene carrying thioester pendants were synthesized via ring-opening metathesis polymerization (ROMP) of alkyl cyclopent-3-enecarbothioate catalyzed by a ruthenium-based commercial catalyst and subsequent hydrogenation of the ROMP products (alkyl 5 ethyl, nbutyl, n-octyl, or n-dodecyl). In these polymers the pendant alkyl thioester groups are precisely distributed along the backbone on every five methylene carbons. Chain structure, molecular weight and molecular weight distribution of the polymers were characterized by 1 H and 13 C NMR, and GPC. The ROMP reactions all reached high monomer conversions, and hydrogenation of the ROMP products were exhaustive. Thermal transitions and side chain crystallization behaviors of the polymer were investigated and characterized by DSC and TGA. Glass transition temperature and melting temperature of these polymers were higher than the counterparts containing ester pendants. TGA analysis indicated that all the thioester-containing polymers exhibited moderate thermal stability, and the sulfurcontaining polymers show slightly lower thermal stability than their counterparts without sulfur. The new family of functionalized polyethylenes could be used as models of ethylenethioacrylate copolymers, and find applications as novel functional materials.

Polypentenamer Renaissance: Challenges and Opportunities

“…76 Thioester-containing polypentenamers with similar pendant alkyl groups showed higher T g and T m but reduced thermal stability. 77 Our group's entry point to polypentenamers research came from the ROMP of 4-phenylcyclopentene (5) to produce a precision styrenic rubber (P4PCP) or ethylene-styrene (ES) "like" copolymer (H 2 −P4PCP) following hydrogenation ( Figure 6). 51 Here we reemphasize that, due to the 5-carbon phenyl branch spacing, accessing this microstructure through ES copolymerization is not possible.…”

“…With synthetic progress taking large strides, exploration of thermal and physical properties toward potential applications for functionalized polypentenamers is highly needed. Fan and co-workers recently reported a series of homoallylic ester or thioester-substituted CPs where they systematically increased the size of the ester pendant alkyl group. − The T g of the resulting polymers was shown to decrease from −26 °C to −65 °C as the ester pendant was increased from methyl to n -octyl . With n -dodecyl pendants and higher, semicrystalline properties arose from the long alkyl chains .…”

“…With n -dodecyl pendants and higher, semicrystalline properties arose from the long alkyl chains . Thioester-containing polypentenamers with similar pendant alkyl groups showed higher T g and T m but reduced thermal stability …”

Well-Defined and Precision-Grafted Bottlebrush Polypentenamers from Variable Temperature ROMP and ATRP

“…ROMP of cyclopentene (CP) derivatives has been largely overshadowed due to their low ring strain, [Δ H p ] = ∼23 kJ mol –1 , which reduces polymerization kinetics and limits high conversions due to the thermodynamics of the equilibrium ROMP. However, ROMP of CP and derivatives has received heightened interest within the last several years. − Recently, we reported a method to achieve high conversion, targeted molar mass, and low dispersity ( Đ ) PCP by altering the temperature during ROMP . This method, which we termed variable temperature ROMP (VT-ROMP), initiates polymerization at warm temperature and propagates CP to high conversion by cooling after initiation is complete.…”

Cross-Linked Polythiomethacrylate Esters Based on Naphthalene—Synthesis, Properties and Reprocessing

“…They showed good thermal properties such as 5% weight loss temperature (T 5 ) in the range 307–301 °C and T g s in the range 65–110 °C due to the introduction of alicyclic and ester groups in the polymer chains, which endow chain rigidity. Song et al [ 64 ] prepared a functional polyethylene carrying thioester pendants via ring-opening metathesis polymerization (ROMP) of alkyl cyclopent-3-enecarbothioate catalyzed by a ruthenium-based catalyst. They investigated the thermal properties of obtained materials and they reported that the thioester groups were decomposed at 300–400 °C to release volatile fragments of the side groups, and decomposition of polymer backbone was initiated at temperature above 400 °C.…”