Great advances have been made in various 3D printing methods for ceramics. Fabrication of Si‐based ceramics using polymer‐derived ceramics (PDCs) is gaining popularity. Using this route, preceramic polymers can be shaped in the polymer state and then pyrolyzed to produce different types of ceramics. Cellular ceramics can be manufactured using this technique. Herein, the novel fabrication of cellular ceramics with a two‐step process using PDCs is reported. First cellular structures are 3D printed with fused filament fabrication (FFF) using thermoplastic polyurethane and impregnated with preceramic polymer polysilazane. Second, pyrolysis of the impregnated structure produces a self‐similar ceramic cellular structure. The impact of 1) catalysts, 2) curing environment, and 3) pyrolysis sequence optimization to form cellular ceramics with fully dense SiOC(N) struts are systemically evaluated. The resultant custom ceramic components can tolerate operating temperatures of 1500 °C and can be manufactured for less than 5% of the cost of competing methods. The ceramic material is shown to be biocompatible and promotes fast cell adhesion. Finally, early‐stage cell activation on the SiOC(N) structure is shown to be tunable by adjusting the porosity with this 3D printing to mimic the bone tissue geometry for bone regeneration.
Chain-end-labeled
polymers are interesting for a range of applications.
In polymer nanomedicine, chain-end-labeled polymers are useful to
study and help understand cellular internalization and intracellular
trafficking processes. The recent advent of fluorescent label-free
techniques, such as nanoscale secondary ion mass spectrometry (NanoSIMS),
provides access to high-resolution intracellular mapping that can
complement information obtained using fluorescent-labeled materials
and confocal microscopy and flow cytometry. Using poly(
N
-(2-hydroxypropyl)methacrylamide) (PHPMA) as a prototypical polymer
nanomedicine, this paper presents a synthetic strategy to polymers
that contain trace element labels, such as fluorine, which can be
used for NanoSIMS analysis. The strategy presented in this paper is
based on reversible addition fragmentation chain transfer (RAFT) polymerization
of pentafluorophenyl methacrylate (PFMA) mediated by two novel chain-transfer
agents (CTAs), which contain either one (α) or two (α,ω)
fluorine labels. In the first part of this study, via a number of
polymerization experiments, the polymerization properties of the fluorinated
RAFT CTAs were established.
19
F NMR spectroscopy revealed
that these fluorinated RAFT agents possess unique spectral signatures,
which allow to directly monitor RAFT agent conversion and measure
end-group fidelity. Comparison with 4-cyanopentanoic acid dithiobenzoate,
which is a standard CTA for the RAFT polymerization of PFMA, revealed
that the introduction of one or two fluorine labels does not significantly
affect the polymerization properties of the CTA. In the last part
of this paper, a proof-of-concept study is presented that demonstrates
the feasibility of the fluorine-labeled poly(pentafluorophenyl methacrylate)
polymers as platforms for the postpolymerization modification to generate
PHPMA-based polymer nanomedicines.
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