A bottom/up approach for the study of the crystal structure of sustainable and eco-friendly polymers and the relationships with properties – ECOPOLYCRYS

The design and application of sustainable polymers is a remarkable scientific goal demanded by the modern society at a global level.
The in-depth knowledge of the molecular structure of polymers is of fundamental importance in the macromolecular science and
technology to design materials with tailored properties for specific applications. The ECOPOLYCRYS (ECo-friendly POLYmer CRYstal
Structure) project is aimed at studying the crystal structure and the relationships with properties of sustainable and eco-friendly
polymers by using modern X-ray diffraction methods. In addition to the traditional reciprocal-space methods, mainly applicable in the
case of highly crystalline materials, innovative direct-space methods based on global-optimization algorithms, such as Simulated
Annealing, will be developed, implemented and applied.
ECOPOLYCRYS will carry out high-performance computational approaches to determine the correct polymer crystal structure
corresponding to the best global fit of the 1D experimental X-ray diffraction pattern to the simulated one. The crystallographic
solution process will also exploit information coming from other investigations (diffraction from oriented samples, solid-state NMR,
electron diffraction). Studies aimed at optimizing the processing conditions to obtain a high level of crystallinity and good-quality
diffraction patterns will be also carried out. A first research line will be focused on the study of the crystal structure of biodegradable
and biobased polyesters and copolyesters, which represent sustainable alternatives to the non-degradable fossil-based common
polyolefins in many applications, thanks to the good processability, high mechanical strength and low price, coupled with easiness to
degradation. Despite the extensive research already conducted on their crystallization behavior, several aspects of the structure of
some crystal modifications remain to be clarified. A second research line will be focused on the study of the
poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), a thermoplastic polymer with high thermal and dimensional stability presenting the
unique feature in the polymer field i.e., the capability to form nanoporous crystalline (NC) phases able to capture from air or water
many guest molecules also if they are present at very low activities, leading to the formation of cocrystalline (CC) phases. Although
many studies of guest sorption on PPO NC samples have been carried out, the structural solution of the NC and CC phases has not
yet been achieved by traditional methods. Understanding the detailed structure of the PPO crystalline modifications will be useful to
get more detailed and quantitative structure-properties correlations for the best comprehension of the application potential of this
nanoporous polymer that, thanks to the ability to high guest-uptake, can be relevant for ecological uses as dense membranes for
organic pollutant control, molecular separations and sensors.
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