Concurrent ring-opening polymerization/polycondensation of lactones and bioaromatic hydroxy-acids yields random copolymers with improved and controlled thermal properties.
Biosuccinic acid, obtainedviasugar fermentation, is cyclodimerized and oxidized to yield building blocks for aromatic polyesters with high glass transition temperatures.
End-functionalized macromolecular starch reagents, prepared by reductive amination, were grafted onto a urethane-linked polyester-based backbone using copper-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry to produce novel amphiphilic hybrid graft copolymers. These copolymers represent the first examples of materials where the pendant chains derived from starch biopolymers have been incorporated into a host polymer by a grafting-to approach. The graft copolymers were prepared in good yields (63-90%) with high grafting efficiencies (66-98%). Rigorous quantitative spectroscopic analyses of both the macromolecular building blocks and the final graft copolymers provide a comprehensive analytical toolbox for deciphering the reaction chemistry. Due to the modular nature of both the urethane-linked polyester synthesis and the postpolymerization modification, the starch content of these novel hybrid graft copolymers was easily tuned from 28-53% (w/w). The uptake of two low molecular weight guest molecules into the hybrid polymer thin films was also studied. It was found that binding of 1-naphthol and pterostilbene correlated linearly with amount of starch present in the hybrid polymer. The newly synthesized graft copolymers were highly processable and thermally stable, therefore, opening up significant opportunities in film and coating applications. These results represent a proof-of-concept system for not only the construction of starch-containing copolymers, but also the loading of these novel polymeric materials with active agents.
Previous research has demonstrated that amine polymers
rich in
primary and secondary amines supported on mesoporous substrates are
effective, selective sorbent materials for removal of CO
2
from simulated flue gas and air. Common substrates used include
mesoporous alumina and silica (such as SBA-15 and MCM-41). Conventional
microporous materials are generally less effective, since the pores
are too small to support low volatility amines. Here, we deploy our
newly discovered zeolite nanotubes, a first-of-their-kind quasi-1D
hierarchical zeolite, as a substrate for poly(ethylenimine) (PEI)
for CO
2
capture from dilute feeds. PEI is impregnated into
the zeolite at specific organic loadings. Thermogravimetric analysis
and porosity measurements are obtained to determine organic loading,
pore filling, and surface area of the supported PEI prior to CO
2
capture studies. MCM-41 with comparable pore size and surface
area is also impregnated with PEI to provide a benchmark material
that allows for insight into the role of the zeolite nanotube intrawall
micropores on CO
2
uptake rates and capacities. Over a range
of PEI loadings, from 20 to 70 w/w%, the zeolite allows for increased
CO
2
capture capacity over the mesoporous silica by ∼25%.
Additionally, uptake kinetics for nanotube-supported PEI are roughly
4 times faster than that of a comparable PEI impregnated in SBA-15.
It is anticipated that this new zeolite will offer numerous opportunities
for engineering additional advantaged reaction and separation processes.
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