TY - JOUR
T1 - Entropically Driven Macrolide Polymerizations for the Synthesis of Aliphatic Polyester Copolymers Using Titanium Isopropoxide
AU - Amador, Adrian G.
AU - Watts, Annabelle
AU - Neitzel, Angelika E.
AU - Hillmyer, Marc A.
PY - 2019/3/26
Y1 - 2019/3/26
N2 - Thermal and mechanical properties of sustainable aliphatic polyesters can be tuned through the synthesis of copolymers. The synthesis of two 14-membered macrolides are reported: a cyclic tetraester with alternating lactic acid (LA) and 3-hydroxypropionic acid (3HP) units and a cyclic diester with alternating glycolic acid (GA) and 2-methyl-1,3-propanediol (2MD) units. Ring-opening transesterification polymerization (ROTEP) of these macrolides to yield poly(LA-stat-3HP) and poly(GA-alt-2MD), respectively, were found to be modestly endothermic (ΔHp ° = 2.0 and 0.5 kJ mol -1 , respectively) and endoentropic (ΔSp ° = 27 and 23 J mol -1 K -1 , respectively). Inexpensive and nontoxic titanium isopropoxide Ti(Oi-Pr) 4 functions as an active catalyst for these entropically driven ROTEPs, achieving high conversions (>90%) in under 1 h. The polymerizations exhibit control over molar mass with dispersity values <1.7. poly(GA-alt-2MD) is an amorphous polymer with a low glass transition temperature near -30 °C. poly(LA-co-3HP) exhibits a glass transition temperature up to 13 °C and, depending on the regioregularity, exhibits a melting temperature up to 96 °C.
AB - Thermal and mechanical properties of sustainable aliphatic polyesters can be tuned through the synthesis of copolymers. The synthesis of two 14-membered macrolides are reported: a cyclic tetraester with alternating lactic acid (LA) and 3-hydroxypropionic acid (3HP) units and a cyclic diester with alternating glycolic acid (GA) and 2-methyl-1,3-propanediol (2MD) units. Ring-opening transesterification polymerization (ROTEP) of these macrolides to yield poly(LA-stat-3HP) and poly(GA-alt-2MD), respectively, were found to be modestly endothermic (ΔHp ° = 2.0 and 0.5 kJ mol -1 , respectively) and endoentropic (ΔSp ° = 27 and 23 J mol -1 K -1 , respectively). Inexpensive and nontoxic titanium isopropoxide Ti(Oi-Pr) 4 functions as an active catalyst for these entropically driven ROTEPs, achieving high conversions (>90%) in under 1 h. The polymerizations exhibit control over molar mass with dispersity values <1.7. poly(GA-alt-2MD) is an amorphous polymer with a low glass transition temperature near -30 °C. poly(LA-co-3HP) exhibits a glass transition temperature up to 13 °C and, depending on the regioregularity, exhibits a melting temperature up to 96 °C.
UR - http://www.scopus.com/inward/record.url?scp=85063135477&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85063135477&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.9b00065
DO - 10.1021/acs.macromol.9b00065
M3 - Article
AN - SCOPUS:85063135477
SN - 0024-9297
VL - 52
SP - 2371
EP - 2383
JO - Macromolecules
JF - Macromolecules
IS - 6
ER -