Unsaturated Poly(ester-urethanes) with Stereochemically Dependent Thermomechanical Properties

Abstract

Polymer crystallinity is known to be dependent upon backbone stereochemistry and this concept has emerged as an effective means of altering bulk material properties. Herein, we describe a simple, step-growth polymerization to synthesize unsaturated poly(ester-urethane)s using the thiol-Michael addition reaction. The absolute control of alkene stereochemistry (0−100 % trans content) in the polymer backbone was achieved by varying the cis/trans double bond content of the monomer feedstock. In turn, the crystallinity of the polymer was systematically varied which manifested in control over the resultant tensile properties such as Young's modulus, ultimate tensile strength and elongation at break. Generally, the crystallinity and tensile strength were positively correlated with increasing trans double bond content within the polymer.

Stereocontrolled Acyclic Diene Metathesis Polymerization

“…DSC revealed a clear influence of cis-alkene content on thermal transitions as depicted in the thermograms in Fig. 5d-f, which is in line with reports by Buchard 39 and Dove and Becker 3,40 . In addition to small variations of glass transition temperatures (Tg), striking differences in crystalline behavior were observed.…”

Understanding structure–property relationships of main chain cyclopropane in linear polyesters

“…Whilst this is a contrast to several previously reported cis/trans polymer systems, the low cyclopropane content within this system could inhibit the influence of stereochemistry. 29,30 Further increase of the trans-cyclopropane content to 25% led to a more flexible and weaker material. BD 75 Cy(trans) 25 -co-HDT possessed an average Young's modulus of 60 MPa in comparison to BD-co-HDT which was 105 MPa.…”

“…However, previous investigations report that changing the cis/trans content of linear polymers led to a control of bulk crystallinity, and hence, tensile properties could be tuned. 29,31 The lack of crystallinity in the initial cyclopropane-containing polymers demonstrates that neither stereochemistry promotes crystallisation. Therefore, we observe minimal differences in tensile properties between the cis and trans stereochemistry in this cyclopropane system.…”

Ru-Catalyzed, cis-Selective Living Ring-Opening Metathesis Polymerization of Various Monomers, Including a Dendronized Macromonomer, and Implications to Enhanced Shear Stability

“…17 The cis-olefin content in unsaturated polymers is also known to dramatically influence their optoelectric properties and solubility 18−20 as well as crystallinity and tensile properties. 21 Thus, controlling the cis-olefin content in a polymer is essential for tuning its properties.…”

“…Furthermore, the glass transition temperature ( T g ) of high cis -olefin content PNB (prepared from ROMP of endo , exo -5,6-norbornene) is 30 °C higher than that of the corresponding high trans -olefin content PNB . The cis -olefin content in unsaturated polymers is also known to dramatically influence their optoelectric properties and solubility − as well as crystallinity and tensile properties . Thus, controlling the cis- olefin content in a polymer is essential for tuning its properties.…”