Semi-crystalline polymethylene-b-poly(acrylic acid) diblock copolymers: aggregation behavior, confined crystallization and controlled growth of semicrystalline micelles from dilute DMF solution

Abstract

In this paper, we have systematically investigated the aggregation behavior, confined crystallization and controlled growth of a novel polyolefin analogue-containing block copolymers (BCPs), i.e., polymethylene-b-poly(acrylic acid) diblock copolymers (PM-b-PAA). On cooling from a homogenous DMF solution at 80 °C, PM-b-PAA was found to crystallize and aggregate with well-defined disk-like micelles. The aggregate behavior and in-plane morphology of PM-b-PAA could be easily controlled by modifying the block ratio, solution pH and solvent composition (DMF-water), by manipulating the crystallization of PM block and the stretching degree of solvated PAA corona. Further investigation of the crystalline feature of PM-b-PAA indicated that the crystallization of PM was retarded by tethered amorphous PAA segments. The crystalline micelle could construct a nano-confined environment with PM folding as the core into a thickness of the mono-layered polyethylene. Finally, when cultured in dilute DMF solution at 50 °C, the initial crystalline micelles, being as self-seeds, could follow a living growth mechanism and develop into single crystals, with well-defined lozenge-shaped morphology.

Polymethylene-b-poly(acrylic acid) diblock copolymers: Morphology and crystallization evolution influenced by polyethyene polyamine with dual confinement effects

“…In recent years, block copolymers (BCPs) have attracted abiding interest, owing to their various morphologies in bulk or solution, [1][2][3][4] which is caused by the thermodynamic incompatibility of the different polymer segments. [5][6][7] The morphologies are mainly including spheres, cylinders, lamellae and vesicles. [8][9][10] The ordered nano-structures are widely used in catalysts and drugs delivery as nano-reactors.…”

“…[12][13][14] In all, block copolymers can be spontaneously constructed well-ordered periodic structures and have wide applications in the fields of lithography, industrial catalysis, biomedical, and optoelectronics technology. [5,8,15,16] As one unique species, semi-crystalline BCPs, which contain at least one crystallizable chain segment, have aroused wide concern in the last decade. [17][18][19] Frequently used crystalline block components are polyethylene (PE), [1,[20][21][22] polyethylene oxide (PEO) [20][21][22][23][24] and polycaprolactone (PCL).…”

“…Currently, researches on the semi-crystalline BCPs are mainly concentrated in the following respects: 1), to regulate the self-assembly morphologies of crystalline BCPs by chain structures and various external parameters, which change the relative strength of crystallization and other driving forces in the bulk, in thin film and in solution. [5,8] For example, He et al investigated the effect of inorganic salt on the micellar morphology of semicrystalline PCL-b-PEO in aqueous solution, and the results indicated that the inorganic salt can induce sphere-to-rod or sphere-to-lamella transformations of the PCL-b-PEO micelles in aqueous solution, which can be explained with the reduced tethering density (σ ). [32] 2), some studies on highly asymmetric lamellar structures, [33] single crystals, [5,8] co-micelles [26,34] or controlled growth of semi-crystalline micelles [5,26] in which aggregation, crystallization are 'free' in the absence of other chemicals.…”

How a Small Modification of the Corona-Forming Block Redirects the Self-Assembly of Crystalline–Coil Block Copolymers in Solution

“…To prepare fiber-like micelles of the non-quaternized PFS 17 heated to 90 C as described above, cooled to room temperature and allowed to age for 24 h.…”

“…6,9,10 The first rod-like micelles reported involved poly(ferrocenyldimethylsilane) (PFS) block copolymers. [11][12][13] Other more recent examples of rod-like micelles involve block copolymers with polyethylene (PE), 7,[14][15][16][17][18][19][20] polyacrylonitrile (PAN), 21 polyferrocenyldimethylgermane (PFG), 22 poly(e-caprolactone) (PCL), [23][24][25][26][27][28][29][30] poly(L-lactide) (PLLA), [31][32][33][34][35] and polythiophene, 36,37 as the crystalline core-forming block.…”