TY - JOUR
T1 - Hydrogen-Bonding Bottlebrush Networks
T2 - Self-Healing Materials from Super-Soft to Stiff
AU - Xie, Renxuan
AU - Lapkriengkri, Intanon
AU - Pramanik, Nabendu B.
AU - Mukherjee, Sanjoy
AU - Blankenship, Jacob R.
AU - Albanese, Kaitlin
AU - Wang, Hengbin
AU - Chabinyc, Michael L.
AU - Bates, Christopher M.
N1 - Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/12/13
Y1 - 2022/12/13
N2 - The impact of polymer architecture on network dynamics and self-healing is presented using bottlebrushes containing side chains that are end-functionalized with 2-ureido-4[1H]-pyrimidinone (UPy). The synthesis of these materials is straightforward through a three-step process: (1) synthesizing rubbery poly(4-methylcaprolactone) macromonomers (p4MCL-OH) with a norbornene-based initiator, (2) functionalizing the terminal hydroxyl group with UPy-isocyanate (p4MCL-UPy), and (3) statistically copolymerizing p4MCL-OH and p4MCL-UPy via ring-opening metathesis polymerization (ROMP) to form hydrogen-bonding bottlebrushes having a fraction (p) of side chains functionalized with UPy. Attaching UPy to the free end of bottlebrush side chains dilutes the impact of friction from complementary UPy interactions on segmental dynamics, leading to a much weaker dependence of the glass-transition temperature (Tg) on p than observed in linear analogues, while the activation energy to dissociate UPy-UPy bonds (41-47 kJ/mol) remains mostly unchanged. Longer side chains result in a competition between reducing Tg and inducing entanglements that influence hydrogen-bonded network dynamics. Increasing the backbone length extends the sticky Rouse region without affecting the network modulus (Gx) or UPy-UPy dissociation time (τs). Gx scales linearly with p and ranges from 27 kPa to 1.6 MPa, while τs remains nearly constant in contrast to linear telechelic ionomers, implying a similar self-healability across bottlebrush networks containing different amounts of UPy. These stretchable networks with p ≤ 0.25 undergo self-healing upon repeated rupture and melt pressing at ≤100 °C while retaining similar tensile properties. In summary, decorating bottlebrush polymers with hydrogen bonds creates opportunities to independently manipulate associative network dynamics and mechanical moduli.
AB - The impact of polymer architecture on network dynamics and self-healing is presented using bottlebrushes containing side chains that are end-functionalized with 2-ureido-4[1H]-pyrimidinone (UPy). The synthesis of these materials is straightforward through a three-step process: (1) synthesizing rubbery poly(4-methylcaprolactone) macromonomers (p4MCL-OH) with a norbornene-based initiator, (2) functionalizing the terminal hydroxyl group with UPy-isocyanate (p4MCL-UPy), and (3) statistically copolymerizing p4MCL-OH and p4MCL-UPy via ring-opening metathesis polymerization (ROMP) to form hydrogen-bonding bottlebrushes having a fraction (p) of side chains functionalized with UPy. Attaching UPy to the free end of bottlebrush side chains dilutes the impact of friction from complementary UPy interactions on segmental dynamics, leading to a much weaker dependence of the glass-transition temperature (Tg) on p than observed in linear analogues, while the activation energy to dissociate UPy-UPy bonds (41-47 kJ/mol) remains mostly unchanged. Longer side chains result in a competition between reducing Tg and inducing entanglements that influence hydrogen-bonded network dynamics. Increasing the backbone length extends the sticky Rouse region without affecting the network modulus (Gx) or UPy-UPy dissociation time (τs). Gx scales linearly with p and ranges from 27 kPa to 1.6 MPa, while τs remains nearly constant in contrast to linear telechelic ionomers, implying a similar self-healability across bottlebrush networks containing different amounts of UPy. These stretchable networks with p ≤ 0.25 undergo self-healing upon repeated rupture and melt pressing at ≤100 °C while retaining similar tensile properties. In summary, decorating bottlebrush polymers with hydrogen bonds creates opportunities to independently manipulate associative network dynamics and mechanical moduli.
UR - http://www.scopus.com/inward/record.url?scp=85143510366&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85143510366&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.2c01886
DO - 10.1021/acs.macromol.2c01886
M3 - Article
AN - SCOPUS:85143510366
SN - 0024-9297
VL - 55
SP - 10513
EP - 10521
JO - Macromolecules
JF - Macromolecules
IS - 23
ER -