Hydrolysable Ureas

Patent Title: DYNAMIC UREA BONDS WITH FAST HYDROLYTIC KINETICS FOR POLYMERS

Number/Link: WO2017/155958

Applicant/Assignee: Univ. Illinois

Publication Date: 14 September 2017

“Gist”: Hindered urea bonds with fast hydrolysis kinetics are prepared from aromatic-sbstituted diamines and diisocyanates

Why it is interesting: Polyurethanes containing thermally reversible hindered urea bonds (HUBs) have been discussed before in this blog. In the current case the HUBs are prepared from aromatic (e.g aryl-) substituted amines and are said to show fast, pH-independent, hydrolysis kinetics. The HUBs can be built into linear or crosslinked polyurethanes or other polymers like polyamides, polycarbonates etc.  The resulting materials are useful for medical applications like drug delivery, water-degradable packaging, self-healing materials and the like.

HUB hysdrolysis

Hydrolysis reaction of phenyl-N-tetrabutyl-N-ethyl urea

 

PET-Lignin Polyols

Patent Title: HIGH RECYCLE CONTENT POLYOLS FROM THERMOPLASTIC POLYESTERS AND LIGNIN OR TANNIN

 Number/Link: WO2016/118411

Applicant/Assignee: Resinate Materials Group

Publication date: 28-07-2016

Gist”: PET is glycolized and then reacted with lignin or tannin

Why it is interesting: This application is about ‘sustainable’ aromatic polyester polyols partly based on recycled materials and partly on biorenewable materials. According to the invention the polyols can be prepared by first glycolizing (waste) PET and subsequently reacting the mixture with lignin at 110-210°C while removing volatile condensation products.  The resulting polyols (pref) show a OH value between 40 and 400 mg KOH/g, a fn of 2-2.2 and a viscosity at 25°C of 500 to 3000 cP. In the examples polyols with up to 25 wt% lignin are shown. The polyols are said to be useful e.g. in 2K PU coating compositions.

Part of a lignin structure

Part of a lignin structure

Enzymatic Recycling of Polyurethanes

Title: PROCESS FOR THE MATERIAL UTILIZATION OF POLYURETHANES

 Number/Link: WO2013/134801 (German)

Applicant/Assignee: Eurofoam

Publication date: 19-09-2013

Gist”: Use of specific enzymes to break down polyurethane into polyamines and its original (polyether)polyols

Why it is interesting: Chemical recycling of polyurethane by hydrolysis, glycolysis etc. is known but requires high temperatures and sometimes (when supercritical water is used) high pressures.  This can lead to side reactions and the contamination of the recycled raw materials. Enzymatic recycling of polyurethanes is known as well but is mostly limited to polyester polyurethanes and esterase enzymes which break down the ester bonds.  The current invention claims that the use of certain hydrolases of the EC3 class, especially arylacylamidase  EC3.5.1.13 selectively breaks the urethane bond. (EC=enzyme comission number). The reaction can be carried out between 30 and 50°C and at a pH of 9.5 to 11. The resulting polyols and amines can be extracted using a polar solvent. While interesting the proposed process may not be very practical as the example shows that 5 days were needed to recycle a 5 gram sample of a model foam.

Schematic representation of the enzyme catalysed reaction.

Schematic representation of the enzyme catalysed reaction.