Self-Healing Polyurethane Elastomers

Patent Title: POLYURETHANE

 Number/Link: W02016185172

Applicant/Assignee: Croda

Publication date: 24-11-2016

Gist”: PU from polyols which contain both a fatty dimer residue and an H-bonding group, show self-healing properties

Why it is interesting: Polyurethane elastomers with ‘intrinsic’ self-healing properties (i.e. without the need for external chemicals like encapsulated monomers) can be prepared by reacting isocyanates with polyols that have at least one urethane, amide or carbonate group and at least one fatty dimer residue. It is theorized that the fatty dimer allows the soft-phase of the polymer to flow and H-bonds to form, thus restoring most of the properties after damage.  In the examples polyols with internal urethane groups were prepared by reacting C36 dimer diol with HDI, which were then reacted with MDI and BDO. Samples of the resulting elastomers were cut in half, and manually stuck together again under mild heating (60°C), thus recovering most of their tensile and elongation properties.

A dimer diol

A dimer diol

Reactive Polyurethane Plasticizer

Patent Title: REACTIVE POLYURETHANE PLASTICIZERS AND ADHESIVES MADE THEREFROM

 Number/Link: W02016179131

Applicant/Assignee: Dow

Publication date: 10-11-2016

Gist”: An EO/PO monol is reacted with an excess of 4,4′-MDI

Why it is interesting: The invention is about reactive PU plasticizers which are said to be especially useful for polyurethane moisture curing adhesives used in automotive glass bonding. As opposed to conventional plasticizers they will supposedly not migrate and therefore not degrade adhesive properties over time or cause window fogging. The reactive plasticizers are prepared by reacting a slight excess of 4,4′-MDI with and EO/PO monol of MW between 500 and 2000 Da and an EO:PO ratio of about 1:1, such that the resulting in NCO content is between 0.1 and 1%.  Obviously at such low NCO values most of the MDI will have reacted twice with monol, and the resulting non-reactive plasticizer may (in my opinion) well migrate depending on the composition of both monol and adhesive.

4,4'-MDI

4,4′-MDI

 

Highly Tuneable Shape Memory Polyurethanes

Patent Title: PROCESSABLE, TUNABLE THIOL-ENE CROSSLINKED POLYURETHANE SHAPE MEMORY POLYMERS

 Number/Link: WO2016/126703

Applicant/Assignee: Texas A&M University

Publication date: 11-08-2016

Gist”: SMPUs are made from combinations of different diisocyanates and chain extenders and different levels of crosslinking using thiol-ene click chemistry

Why it is interesting: This invention is about shape memory polyurethanes with tuneable glass transition temperature and stiffness. In a first step a low mole weight TPU is prepared from a diisocyanate and a short chain diol including some trimethylolpropane allyether (TMPAE) and allylalcohol as chain stopper. The TPU is then blended with a polythiol and a photoinitiator to allow for UV curing. The Tg can be tuned from 30 and 105°C by combining different types of chain extenders and di-iso’s ranging from DEG-HDI to CHDM-H12MDI.  The modulus (in the rubber state) can be  varied between 0.4 to 20 MPa by controlling the level of crosslinking through the amount of TMPAE and amount and type of polythiol.  The SMPUs are said to be especially useful for biomedical applications.

Reaction scheme of the invention

Reaction scheme of the invention

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