Distinctive Polymorphism-like Isodimorphism in Poly(propylene succinate-ran-propylene fumarate)

Diverse Applications of Two-Dimensional Correlation Spectroscopy (2D-COS)

This second of the two-part series of a comprehensive survey review provides the diverse applications of two-dimensional correlation spectroscopy (2D-COS) covering different probes, perturbations, and systems in the last two years. Infrared spectroscopy has maintained its top popularity in 2D-COS over the past two years. Fluorescence spectroscopy is the second most frequently used analytical method, which has been heavily applied to the analysis of heavy metal binding, environmental, and solution systems. Various other analytical methods including laser-induced breakdown spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, capillary electrophoresis, seismologic, and so on, have also been reported. In the last two years, concentration, composition, and pH are the main effects of perturbation used in the 2D-COS fields, as well as temperature. Environmental science is especially heavily studied using 2D-COS. This comprehensive survey review shows that 2D-COS undergoes continuous evolution and growth, marked by novel developments and successful applications across diverse scientific fields.

Melting Behaviors of Bio-Based Poly(propylene 2,5-furan dicarboxylate)-b-poly(ethylene glycol) Co Polymers Related to Their Crystal Morphology

In this experiment, a series of poly(propylene 2,5-furan dicarboxylate)-b-poly(ethylene glycol) (PPFEG) copolymers with different ratios were synthesized using melt polycondensation of dimethylfuran-2,5-dicarboxylate (DMFD), 1,3-propanediol (PDO) and poly(ethylene glycol) (PEG). The effect of PEG content on the crystallization behavior of the poly(propylene 2,5-furan dicarboxylate) (PPF) copolymers was investigated. For PPF, the nucleation density of the β-crystals was higher than that of α-crystals. As Tc increases, the β crystals are suppressed more, but at Tc = 140 °C, the bulk of PPF has already been converted to α crystals, which crystallize faster at higher nucleation densities, resulting in a difference in polymer properties. For this case, we chose to add a soft segment material, PEG, which led to an early multi-melt crystallization behavior of the PPF. The addition of PEG led to a decrease in the crystallization temperature of PPF, as well as a decrease in the cold crystallization peak of PPF. From the crystalline morphology, it can be seen that the addition of PEG caused the transformation of the PPF crystalline form to occur earlier. From the crystalline morphology of PPF at 155 °C, it can be observed that the ring-banded spherical crystals of the PPF appear slowly with increasing time. With the addition of PEG, spherical crystals of the ring band appeared earlier, and even appeared first, and then disappeared slowly.

Promoting Co-Crystallization in Poly(butylene succinate) and Poly(butylene fumarate) Blends via End-Group Functionalization

Co-crystallization plays a crucial role in the integration and regulation of thermal and mechanical properties in polymer blends, but the poor compatibility of the components in the crystal phase has always been a major obstacle to co-crystallization, which puts forward stricter requests for linkage and interaction between different entities. On the basis of the hydrogen-bonding interaction that can promote chain stacking and thus improve miscibility, we propose that crystalline/crystalline blends of 2-ureido-4[1H]-pyrimidinone (UPy)-functionalized poly(butylene succinate) and poly(butylene fumarate) (PBS-UPy/PBF-UPy) where UPy groups with quadruple hydrogen-bonding interaction are employed to connect different chain ends, could inhibit phase separation and improve co-crystallization. PBS-UPy/PBF-UPy blends exhibit complex component-dependent and cooling-rate-dependent co-crystallization behavior. A high level of co-crystallization occurs in the range of PBS-UPy-rich fractions, and the proportion could approach over 98% under optimized conditions with the aid of UPy quadruple hydrogen bonds interaction. This work enriches the understanding of co-crystallization in crystalline/crystalline polymer blends and provides more possibility for the design of structures and properties of polymer materials.