Three-dimensional
hierarchical nanoporous polymers and carbon nanomaterials
with well-defined superstructures are of great interest for various
intelligent applications, whereas a facile and versatile approach
to access those materials with a high surface area, stable well-defined
morphology, and ordered pores still remains a significant challenge.
Herein, we report a self-regulated Lewis acid–base interaction-mediated
assembly strategy for the in situ synthesis of morphology-engineered
hyper-cross-linked porous polymers and carbon materials. A series
of functionalized aromatic compounds (FAC) is subjected to self-cross-linking via classic Friedel–Crafts chemistry to achieve stable
porous polymers with a high surface area. Varying the monomer/catalyst
combination had a dramatic effect on the acid–base interaction,
facilitating the tailoring of the self-assembled morphologies from
nanotubes to hollow nanospheres, and even nanosheets. A mechanistic
study showed that the byproducts generated during cross-linking orchestrate
the interactions between the catalyst (acid) and FAC (base) and simultaneously
drive the self-assembly to yield specific morphologies. Based on the
rigid hollow polymer framework and intrinsic hydroxyl functionality,
the hyper-cross-linked hollow nanospheres were easily transformed
to an acid-functionalized catalyst for efficient biodiesel production.
Moreover, high-quality porous carbonaceous nanocounterparts such as
carbon nanotubes, hollow carbon nanospheres, and carbon nanosheets
could also be produced by direct pyrolysis of the corresponding polymer
precursors. These findings may provide guidance for the facile design
of morphology-controlled functionalized polymers and carbon nanomaterials
for various applications.
Porous organic polymers have received considerable attention in recent years because of their applicability as biomaterials. In particular, their hierarchical pore structures, variable morphologies, and tunable biological properties make them...
This study presents an efficient
and systematic approach to synthesize
bioapplicable porous hollow polymeric capsules (HPCs). The hydroxyl-functionalized
nanoporous polymers with hollow capsular shapes could be generated via the moderate Friedel–Crafts reaction without
using any hard or soft template. The numerous primitive hydroxyl groups
on these HPCs were further converted to carboxyl groups. Owing to
the abundance of highly branched carboxyl groups on the surface of
the HPCs, biomolecules [such as folic acid (FA)] could be covalently
decorated on these organic capsules (FA-HPCs) for drug delivery applications.
The intrinsic hollow porosities and specific targeting agent offered
a maximum drug encapsulation efficiency of up to 86% and drug release
of up to 50% in 30 h in an acidic environment. The in vitro studies against cancer cells demonstrated that FA-HPCs exhibited
a more efficient cellular uptake and intracellular doxorubicin release
than bare HPCs. This efficient approach to fabricate carbonyl-functionalized
hollow organic capsules may open avenues for a new type of morphological-controlled
nanoporous polymers for various potential bioengineering applications.
A green and efficient method has been developed to fabricate sulfonic acid-functionalized hollow acidic spherical catalysts with tunable shell thicknesses.
A sensor
for the determination of diols using 3-aminophenylboronic
acid (APBA)-functionalized hyper-cross-linked polypyrene (PPy) (APBA@PPy)
is presented. The uniform (∼1 μm in diameter) and highly
porous (628 m
2
g
–1
in specific surface
area) PPy spheres are fabricated via a one-pot protocol that consists
of ZnBr
2
-catalyzed alkylation of pyrene, a subsequent cross-linking
reaction, and concomitant self-assembly. The PPy spheres formed within
a few minutes at mild conditions are featured by an excellent structural
integrity and inertness to organic solvents. Thus, the APBA@PPy composites
(∼1 μm in diameter; 458 m
2
g
–1
in specific surface area) are prepared simply by substituting unreacted
bromomethyl groups on the surface of PPy spheres for APBA. The APBA@PPy
composites are successfully applied for the electrochemical sensing
of
d
-glucose and dopamine. A dye displacement assay is also
performed using alizarin red dye conjugated to boronic acid in glucose
buffer solution.
Poly(glycerol sebacate)
(PGS), produced from renewable monomers
such as sebacic acid and glycerol, has been explored extensively for
various biomedical applications. However, relatively less attention
has been paid to explore PGS as sustainable materials in applications
such as elastomers and rigid plastics, primarily because of serious
deficiencies in physical properties of PGS. Here, we present two new
approaches for enhancing the properties of PGS; (i) synthesizing block
copolymers of PGS with poly(tetramethylene oxide)glycol (PTMO) and
(ii) preparing a blend of PGS-b-PTMO with a poly(ester–ether)
thermoplastic elastomer. The consequence of molar ratio (hard and
soft segments) and Mn of soft segment
on tensile properties of the material was investigated. The PGS-b-PTMO with 25:75 mole ratios of hard and soft segments
and having a medium Mn soft segment (5350
g mol–1) exhibits an appreciable increase in percentage
of elongation that is from 32% for PGS to 737%. Blends of PGS-b-PTMO and a thermoplastic polyester elastomer, Hytrel 3078,
form a semi-interpenetrated polymer network, which exhibits increased
tensile strength to 2.11 MPa and percentage of elongation to 2574.
An elongation of such magnitude is unprecedented in the literature
for predominantly aliphatic polyesters and demonstrates that the simple
polyester can be tailored for superior performance.
Sulfonic acid functionalized porous polyaromatics are highly active and recyclable heterogeneous catalysts for biodiesel production from vegetable oils.
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