Study of hydrogen‐bonding strength in poly(ϵ‐caprolactone) blends by DSC and FTIR

Abstract

The hydrogen‐bonding strength of poly(ϵ‐caprolactone) (PCL) blends with three different well‐known hydrogen‐bonding donor polymers [i.e., phenolic, poly(vinyl‐phenol) (PVPh), and phenoxy] was investigated with differential scanning calorimetry and Fourier transform infrared spectroscopy. All blends exhibited a single glass‐transition temperature with differential scanning calorimetry, which is characteristic of a miscible system. The strength of interassociation depended on the hydrogen‐bonding donor group in the order phenolic/PCL > PVPh/PCL > phenoxy/PCL, which corresponds to the q value of the Kwei equation. In addition, the interaction energy density parameter calculated from the melting depression of PCL with the Nishi–Wang equation resulted in a similar trend in terms of the hydrogen‐bonding strength. Quantitative analyses on the fraction of hydrogen‐bonded carbonyl groups in the molten state were made with Fourier transform infrared spectroscopy for all systems, and good correlations between thermal behaviors and infrared results were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1348–1359, 2001

Unidirectional Dimerization and Stacking of Ureidopyrimidinone End Groups in Polycaprolactone Supramolecular Polymers

“…This value of the melting transition of caprolactone corresponds to the values reported in the literature. 60,63,64 At 62°C, at a somewhat higher temperature than the second melting peak in DSC, a significant shift of the band at 1668 cm -1 to 1661 cm -1 ( Figure 1B) was observed, and therefore, this transition is ascribed to melting of the UPy moieties. Another way of plotting the same data can give a clearer view of melting of the two parts of the polymers.…”

Solid State and Thermal Behavior of 17β-Estradiol in Ammonioethyl Methacrylate Ester Copolymer

“…A single T g point is an indication of full miscibility of a polymer blend (Kuo 2001a;Kuo 2001b;Maldonado-Santoyo 2004). On the contrary, an immiscible polymer blend exhibits more than one T g representing T g of amorphous pure polymers used as components (Kuo 2001a).…”

“…Partially miscible or immiscible blends do not typically show the depression of melting point whereas a miscible blend displays the melting point depression when the content of amorphous polymer increases. The temperature reduction was a result of morphological effects and thermodynamic reasons (Kuo 2001a;Kuo 2001b). In a thermodynamically miscible blend, an amorphous polymer resides inside the interlamellar regions of a semi-crystalline polymer.…”

“…This peak corresponded to free hydroxyl group absorption (Kuo 2001a;Kuo 2001b;Wiranidchapong 2006;Wiranidchapong 2008;Wiranidchapong 2009). The appearance of this peak was agreed with the water loss during heating.…”

“…In reciprocal way, the positive q value indicates that the self-associated hydrogen bonding is weaker than the inter-associated hydrogen bonding. The higher q value, the stronger hydrogen bonding (Kuo 2001a;Kuo 2001b). The third order equation of the proposed model considers the contact interaction energies (K 1 ≠ 0) and the influence of the molecular neighborhood on the contact energy (K 2 ≠ 0), so that Equation (15) can be written in the term of the corrected weight fraction of the stiffer polymer as displayed below;…”