Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Crystallization-Arrested Viscoelastic Phase Separation in Semiconducting
  Polymer Gels   Through a combination of rheological characterization and
temperature-variable imaging methods, a novel gelation pathway in dilute
solutions of a semiconducting polymer to achieve interconnected, crystalline
networks with hierarchical porosity is reported. Upon rapid cooling, solutions
of regioregular poly(3-hexylthiophene) (RR-P3HT) in ortho-dichlorobenzene
formed thermoreversible gels. Temperature-variable confocal microscopy revealed
cooling-induced structural rearrangement to progress through viscoelastic phase
separation. The phase separation process arrested prematurely during the
formation of micron-sized solvent-rich "holes" within the RR-P3HT matrix due to
intrachain crystallization. Cryogen-based scanning electron microscopy of RR
P3HT gels revealed the existence of an interfibrillar network exhibiting
nano-sized pores. Remarkably, these networks formed to equal gel strengths when
a third component, either small molecule phenyl C61 butyric acid methyl ester
(PCBM) or non-crystallizing regiorandom (Rra)-P3HT, was added to the solution.
Organic solar cells in which the active layers were deposited from
phase-separated solutions displayed 45% higher efficiency compared to reference
cells.

22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: stat
9
The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ