Self-reporting dynamic covalent polycarbonate networks

Abstract

Here, we report the first-time development of polycarbonate networks with self-reporting thermoreversible bonding/debonding on demand properties. The reversible linkages within the network are based on a Hetero-Diels-Alder (HDA) moiety, which is able to undergo cleavage and rebonding as a function of temperature within minutes. As HDA pair a phosphoryl dithioester and a cyclopentadiene moiety are employed as bonding and debonding take place in the temperature range between 25-120°C. The degradation and rebonding can be readily traced by visible inspection due to the self-reporting nature of the HDA moiety. In order to prove the reversibility, linear polycarbonates (M w = 4.200-20.000 g mol −1 ) including the reversible linkage in each repeating unit were generated and carefully analyzed using size exclusion chromatography (SEC), UV/Vis analysis and high temperature 1 H NMR spectroscopy.Subsequently, polycarbonate networks bearing HDA unitsallowing the networks to be fully degraded into small moleculeswere synthesized, debonded and bonded several times in the temperature range between 25 and 120°C within minutes. The present study thus introduces fully degradable polycarbonate networks based on a facile chemical concept as a viable alternative to networks based on C-C bond formation that disallow a complete degradation.Scheme 1 General concept of the bonding/debonding on demand polycarbonate. The network is formed via the reaction of a triol species (HDA-triol)which is formed via an HDA reaction of the TriCp-linker and PDT-OHwith dimethylcarbonate using TBD as catalyst. The network is then able to bond and debond on demand due to the HDA units within minutes as a function of the applied temperature. PaperPolymer Chemistry 416 | Polym. Chem., 2017, 8, 414-420This journal is

Covalent Adaptable Network and Self-Healing Materials: Current Trends and Future Prospects in Sustainability

“…Reversible covalent bonds in a polymer framework lead to self-healing, remoldability, plasticity, and potential recyclability. Some articles have been reported related to the dynamic bond in PCs [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. In a similar matter, as occurs during transesterification, carbonates undergo transcarbonation exchange reactions with free hydroxyl groups [ 34 , 47 ].…”

Prevent or Cure—The Unprecedented Need for Self‐Reporting Materials

“…In a different, yet related example based on the HDA chemistry, polymeric methacrylic (HDA‐PMA) [88] or dimethylcarbonate (HDA‐PC) [89] networks have been formed, consisting of a di‐ or tricyclopentadiene (Di‐/TriCp) and a phosphoryl dithioester (PDT), displayed in Figure 8 A,B . While the bonding process for the network formation is carried out at ambient temperatures to avoid early cleavage of the HDA moieties, the debonding process is conducted at elevated temperatures between 30 and 140 °C.…”

“…Reproducedfrom ref [88]. copyright 2016 The authors, Wiley-VCH GmbH, Weinheim (A) and from ref [89]. published by the Royal Society of Chemistry (B-E).…”

Vorbeugen oder Heilen – die beispiellose Notwendigkeit von selbstberichtenden Materialien

“…In einem anderen, jedoch verwandten HDA-basierten Beispiel wurden polymere Netzwerke von Methacryl-(HDA-PMA) [88] bzw.D imethylcarbonat (HDA-PC) [89] gebildet, die aus einem Di-oder Tricyclopentadien (Di-/TriCp) und einem Phosphoryldithioester (PDT) bestehen, dargestellt in Abbildung 8A,B.W ährend der Bindungsprozess fürd ie Netzwerkbildung bei Umgebungstemperaturen durchgeführt wird, um eine vorzeitige Spaltung der HDA-Einheiten zu vermeiden, wird der Ablçseprozess bei erhçhten Te mperaturen zwischen 30 und 140 8 8Cd urchgeführt. Die Prozesse waren über mehrere Kühl-/Heizzyklen reversibel, wie aus der UV/Vis-(Abbildung 8C)u nd 1 H-NMR-Analyse (Abbildung 8D)h ervorgeht.…”