Formation of lamellar structure by competition in crystallization of both components for crystalline–crystalline block copolymers

Biocompatible and biodegradable MOPEO‐b‐PCL diblock copolymer micelles as nanocontainers for drugs

“…Simultaneously, the crystallinity of MOPEO blocks decreases. This fact proves the negative influence of PCL blocks on the crystallization of MOPEO in accordance to the literature data [15]. Furthermore, the X c value for MOPEO blocks turns out to be less than crystal- linity degree for PCL blocks even in the case of DBC1, which MOPEO block is significantly longer than PCL block.…”

“…PEO and PCL are crystallizable and the temperatures of their glass and melting transitions are close [15]. That is why some investigations of DBC structural characteristics were carried out with application of DSC.…”

“…According to the literature data [15] and the changes in the relative intensity (DH m ) of all the melting peaks with DBC content (Table 2), one could be assumed that the second melting peak with T m~4 7-51 8C at the first scan would be attributed to the melting transition in PEO microcrystalline domains; moreover, the highest and the most intense melting peak with T m from 57.4 to 64.5 8C (at the first scan) would be assigned to the melting process in separate microcrystalline regions of PCL. One can see, that with increasing in PCL length (and in its weight fraction) the T m values for PCL microcrystalline regions grow to the constant value too.…”

Poly(ethylene glycol)-poly(tetrahydrofuran)-poly(ethylene glycol) triblock copolymer : Synthesis, crystallization behavior and novel morphology

“…Block copolymers, consisting of both crystalline and amorphous segments were widely recognized that their crystallization processes and the resulting crystal morphologies can be significantly influenced by microphase separation in melt [6,7]. However, block copolymers, consisting of different crystalline segments such as the double crystalline block copolymers, usually exhibit much more complicated crystallization behaviors [8,9], including confined crystallization [10][11][12][13], competitive or interactive crystallization and so on [14][15][16]. For these block copolymers, the overall crystallization behavior is influenced by block ratios, nucleation types, crystallization kinetics and characteristics of the individually folded chains [5,[17][18][19].…”

“…Unfortunately, reports on this field are still inadequate till now. Recently, with the comprehensive investigations on crystallization process for block copolymers, the high order structures containing crystal lamellae were frequently discovered [6,[21][22][23][24][25], where several types of spherulites with unusual morphologies such as ring banded spherulite, spherical granular aggregates and double concentric spherulites have been reported [14,15,[26][27][28][29][30][31]. Especially, the double concentric spherulites were only found in poly(ethylene oxide)/poly(!-caprolactone) PEG/PCL block copolymer up to now [14,[26][27][28][29].…”