3D printable liquid crystalline elastomers with tunable shape memory behavior and bio-derived renditions
Described herein are liquid crystalline elastomer compositions comprising aromatic epoxy units crosslinked with alkylene diacid units having alkylene segments containing at least one methylene unit, and/or aromatic epoxy units crosslinked with polyphenolic units, wherein the aromatic epoxy units and alkylene diacid units and/or polyphenolic units are in a molar ratio that results in the liquid crystalline elastomer composition exhibiting a glass transition temperature (T g ) and a thermal stability of the liquid crystalline phase (T lc ) that make them particularly suitable as shape memory materials and for use in methods of additive manufacturing. Methods for producing these compositions and their use in additive manufacturing processes are also described.
1. A liquid crystalline elastomer composition comprising aromatic diepoxy units crosslinked with alkylene diacid units having alkylene segments containing at least one methylene unit, wherein the aromatic diepoxy units and alkylene diacid units are in a molar ratio of 0.5 to 0.7.
2. The composition of claim 1 , wherein said aromatic diepoxy units possess at least two phenyl rings connected by a covalent bond or fused with each other.
3. The composition of claim 1 , wherein said aromatic diepoxy units possess at least three phenyl rings connected by a covalent bond and/or fused with each other.
4. The composition of claim 1 , wherein said alkylene diacid units have alkylene segments containing at least three and up to ten methylene units.
5. The composition of claim 1 , wherein said aromatic diepoxy units possess at least two phenyl rings connected by a covalent bond or fused with each other and said alkylene diacid units have alkylene segments containing at least three and up to ten methylene units.
6. A method of additive manufacturing, the method comprising feeding the liquid crystalline elastomer composition of claim 1 into an additive manufacturing device to produce an object made of said liquid crystalline elastomer composition.
7. The method of claim 6 , wherein said aromatic diepoxy units possess at least two phenyl rings connected by a covalent bond or fused with each other.
8. The method of claim 6 , wherein said aromatic diepoxy units possess at least three phenyl rings connected by a covalent bond and/or fused with each other.
9. The method of claim 6 , wherein said alkylene diacid units have alkylene segments containing at least three and up to ten methylene units.
10. The method of claim 6 , wherein said aromatic diepoxy units possess at least two phenyl rings connected by a covalent bond or fused with each other and said alkylene diacid units have alkylene segments containing at least three and up to ten methylene units.
11. The composition of claim 1 , wherein said aromatic diepoxy units are derived from aromatic diepoxy molecules having the following structure:
wherein Ar is an aromatic portion and the Y groups independently represent a covalent bond or a linking group.
12. A method of producing a liquid crystalline elastomer composition, the method comprising crosslinking aromatic diepoxy molecules with alkylene diacid molecules containing at least one methylene unit at a processing temperature of at least 120° C. to 250° C., wherein the aromatic diepoxy molecules and alkylene diacid molecules are in a molar ratio of 0.5 to 0.7.
13. The method of claim 12 , wherein said aromatic diepoxy molecules have the following structure:
wherein Ar is an aromatic portion and the Y groups independently represent a covalent bond or a linking group.
14. The method of claim 12 , wherein said aromatic diepoxy molecules possess at least two phenyl rings connected by a covalent bond or fused with each other.
15. The method of claim 12 , wherein said aromatic diepoxy molecules possess at least three phenyl rings connected by a covalent bond and/or fused with each other.
16. The method of claim 12 , wherein said alkylene diacid molecules have alkylene segments containing at least three and up to ten methylene units.
17. The method of claim 12 , wherein said aromatic diepoxy molecules possess at least two phenyl rings connected by a covalent bond or fused with each other and said alkylene diacid molecules have alkylene segments containing at least three and up to ten methylene units.