Sustainable gas barrier materials, such as polyglycolide, poly(l-lactide), and poly(ethylene 2,5-furandicarboxylate) are important alternatives to traditional plastics used for packaging where low gas permeability is beneficial. However, high degrees of crystallinity in these materials can lead to undesirably low material toughness. We report poly(ester–amide)s derived from glycolide and diamines exhibiting both high toughness and desirable gas barrier properties. These sustainable poly(ester–amide)s were synthesized from glycolide-derived diamidodiols and diacids. To understand the structure–property relationships of the poly(ester–amide)s, polymers with different numbers of methylene groups were compared with respect to thermal, mechanical, and gas barrier properties. As the number of methylene groups between ester groups increased in the even-numbered series, the melting temperature decreased and oxygen permeability increased. We also found that these polymers are readily degradable under neutral, acidic, and basic hydrolytic conditions. These high-performance poly(ester–amide)s are promising sustainable alternatives to conventional gas barrier materials.
more »
« less
β-Methyl-δ-valerolactone-containing thermoplastic poly(ester-amide)s: synthesis, mechanical properties, and degradation behavior
Poly(ester-amide)s (PEAs) have been prepared from (glucose-derived) β-methyl-δ-valerolactone (MVL) by reaction of MVL-derived diamidodiols with diacid chlorides in solution to form poly(ester-amide)s having alternating diester-diamide subunits. The PEAs formed by this method exhibit plastic properties and are of sufficiently high molecular weight to be tough, ductile materials (stress at break: 41–53 MPa, strain at break: 530–640%). The length of the methylene linker unit ( n = 1,2,3) between amide groups of the diamidodiols affects the Young's modulus; longer linkers reduce the stiffness of the materials. This allows tuning of the properties by judicious choice of precursors. MVL was also converted to a diacid chloride that was then used to prepare a PEA that is 76 wt% MVL-derived. The degradation rates of suspensions of these new PEAs in basic aqueous media were benchmarked and their instability in aqueous acid was also observed. NMR studies were used to detect the hydrolytic degradation products of both these PEAs as well as a structurally simpler analog.
more »
« less
- Award ID(s):
- 1901635
- NSF-PAR ID:
- 10249886
- Date Published:
- Journal Name:
- Polymer Chemistry
- Volume:
- 12
- Issue:
- 9
- ISSN:
- 1759-9954
- Page Range / eLocation ID:
- 1310 to 1316
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)The synthesis and degradation mechanisms of a class of pH-sensitive, rapidly degrading cationic poly(α-aminoester)s are described. These reactive, cationic polymers are stable at low pH in water, but undergo a fast and selective degradation at higher pH to liberate neutral diketopiperazines. Related materials incorporating oligo(α-amino ester)s have been shown to be effective gene delivery agents, as the charge-altering degradative behavior facilitates the delivery and release of mRNA and other nucleic acids in vitro and in vivo . Herein, we report detailed studies of the structural and environmental factors that lead to these rapid and selective degradation processes in aqueous buffers. At neutral pH, poly(α-aminoester)s derived from N -hydroxyethylglycine degrade selectively by a mechanism involving sequential 1,5- and 1,6-O→N acyl shifts to generate bis( N -hydroxyethyl) diketopiperazine. A family of structurally related cationic poly(aminoester)s was generated to study the structural influences on the degradation mechanism, product distribution, and pH dependence of the rate of degradation. The kinetics and mechanism of the pH-induced degradations were investigated by 1 H NMR, model reactions, and kinetic simulations. These results indicate that polyesters bearing α-ammonium groups and appropriately positioned N -hydroxyethyl substituents are readily cleaved (by intramolecular attack) or hydrolyzed, representing dynamic “dual function” materials that are initially polycationic and transform with changing environment to neutral products.more » « less
-
more » « less
Abstract We designed and developed a novel library of tyrosol‐derived poly(ester‐arylate)s that exhibit tunable chemical, thermal, mechanical, and degradative properties. To build the library, the diphenols 4‐hydroxyphenethyl 2‐(4‐hydroxyphenyl)acetate (HTy) and 4‐hydroxyphenethyl 3‐(4‐hydroxyphenyl)propanoate (DTy) are synthesized and subsequently polymerized with various diacids. Characterization of library members is performed in order to assess the impact of chemical structure on polymer properties. Specifically, the relative influence of diphenol pseudosymmetry versus asymmetry, diacid carbon chain length, and diacid bond rigidity on resulting properties is investigated. Diphenol choice greatly impacts resulting polymer thermal properties and processability. HTy‐containing polymers generally have lower melting temperatures compared to their DTy‐derived counterparts and are easier to quench in the amorphous phase. As a result, processing results in greater tunability for HTy‐derived polymers. One specific example was pHTy3, which increased its tensile modulus from 1 GPa to 3 GPa upon drawing. Diacid lengths and bond rigidity also significantly influence thermal, mechanical, and degradative properties. In all, members of this library can be synthesized efficiently, with high molecular weight and exhibit a wide range of properties, motivating future commercial translation.
-
Fast pyrolysis of pine wood was carried out to yield a liquid bio-oil mixture that was separated into organic and aqueous phases. The organic phase (ORG-bio-oil) was characterized by gas chromatography–mass spectroscopy, 31 P-nuclear magnetic resonance spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. It was further used as a raw material for producing a mixture of biphenolic compounds (ORG-biphenol). ORG-bio-oil, ORG-biphenol, and bisphenol-A were reacted with cyanogen bromide to yield cyanate ester monomers. Cyanate esters were characterized using FTIR spectroscopy and were thermally cross-linked to develop thermoset materials. Thermomechanical properties of cross-linked cyanate esters were assessed using dynamic mechanical analysis and compared with those of cross-linked bisphenol-A-based cyanate ester. ORG-biphenol cyanate ester was observed to have a superior glass transition temperature (350–380°C) as compared to bisphenol-A cyanate ester (190–220°C). Cyanate esters derived from bio-oil have the potential to be a sustainable alternative to the bisphenol-A-derived analog.more » « less
-
more » « less
Abstract Thiol–norbornene (thiol–ene) photoclickable poly(ethylene glycol) (PEG) hydrogels are a versatile biomaterial for cell encapsulation, drug delivery, and regenerative medicine. Numerous in vitro studies with these 4‐arm ester‐linked PEG‐norbornene (PEG‐4eNB) hydrogels demonstrate robust cytocompatibility and ability to retain long‐term integrity with nondegradable crosslinkers. However, when transplanted in vivo into the subcutaneous or intraperitoneal space, these PEG‐4eNB hydrogels with nondegradable crosslinkers rapidly degrade within 24 h. This characteristic limits the usefulness of PEG‐4eNB hydrogels in biomedical applications. Replacing the ester linkage with an amide linkage (PEG‐4aNB) mitigates this rapid in vivo degradation, and the PEG‐4aNB hydrogels maintain long‐term in vivo stability for months. Furthermore, when compared to PEG‐4eNB, the PEG‐4aNB hydrogels demonstrate equivalent mechanical properties, crosslinking kinetics, and high cytocompatibility with rat islets and human mesenchymal stem cells. Thus, the PEG‐4aNB hydrogels may be a suitable replacement platform without necessitating critical design changes or sacrificing key properties relevant to the well‐established PEG‐4eNB hydrogels.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D1PY00040C
