Bulk copolymerization of alkyl acrylates and cyclodextrin (CD) host monomers produced a single movable cross-network (SC). The CD units acted as movable crosslinking points in the obtained SC elastomer. Introducing movable crosslinks into a poly(ethyl acrylate/butyl acrylate) copolymer resulted in good toughness (Gf) and stress dispersion. Here, to improve the Young’s modulus (E) and Gf of movable cross-network elastomers, the bulk copolymerization of liquid alkyl acrylate monomer swelling in SC gave another type of movable cross-network elastomer with penetrating polymers (SCPs). Moreover, the bulk copolymerization of alkyl acrylate and the CD monomer in the presence of SC resulted in dual cross-network (DC) elastomers. The Gf of the DC elastomer with a suitable weight % (wt%) of the secondary movable cross-network polymer was higher than those of the SCP or SC elastomers. The combination of suitable hydrophobicity and glass transition of the secondary network was important for improving Gf. Small-angle X-ray scattering (SAXS) indicated that the DC elastomers exhibited heterogeneity at the nanoscale. The DC elastomers showed a significantly broader relaxation time distribution than the SC and SCP elastomers. Thus, the nanoscale heterogeneity and broader relaxation time distribution were important to increase Gf. This method to fabricate SCP and DC elastomers with penetrating polymers would be applicable to improve the Gf of conventional polymeric materials.
Bulk copolymerization of alkyl acrylate and cyclodextrin
(CD) host
monomers forms a single movable cross network (SC), in which the CD
units act as movable cross-linkers. Moreover, the bulk copolymerization
of the CD monomer and main chain monomer in the presence of SC results
in dual-cross-network (DC) elastomers. DC elastomers result in good
toughness (G
f). Here, to improve G
f and Young’s modulus (E), we hybridized DC elastomers with tertiary glassy polymers, which
are called DCP elastomers. We prepared the DCP elastomers by photopolymerization
of N,N-dimethylacrylamide
(DMAA) and poly(2-methoxyethyl acrylate) (MEA) in the presence of
DC. A DCP elastomer with a suitable weight percent (wt %) of the glassy
polymer shows high G
f (108.4 MJ m–3) and E (223.4 MPa) values. Dynamic
mechanical analysis (DMA) and in situ small-angle
X-ray scattering (SAXS) measurements under uniaxial stretching indicate
multiple deformations based on phase-separated structures. We suggest
that the phase-separated structures of DCP elastomers cause a large
stress dissipation, which contributes to high toughness.
Supramolecular cross-links in poly(2-methoxyethyl acrylate) enhanced mechanical properties of the polymers maintaining high blood compatibility. The high blood compatibility suggests a potential for artificial blood vessel.
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