Side‐chain crystallization behavior of graft copolymers consisting of amorphous main chain and crystalline side chains: Poly(methyl methacrylate)‐graft‐poly(ethylene glycol) and poly(methyl acrylate)‐graft‐poly(ethylene glycol)

Abstract

Graft copolymers consisting of amorphous main chain, poly(methyl methacrylate) (PMMA), or poly(methyl acrylate) (PMAc), and crystalline side chains, poly(ethylene glycol) (PEG), have been prepared by copolymerization of PEG macromonomers with methyl methacrylate or methyl acrylate (MMAx or MACx, respectively). Because of the compatibility of PMMA/PEG and PMAc/PEG, from small-angle X-ray scattering results, the main and side chains in graft copolymers were suggested to be homogeneous in the molten state. Differential scanning calorimetry (DSC) cooling scans revealed that PEG side chains for graft copolymers with large PEG fractions were crystallized when the sample was cooled, with a cooling rate of 10°C/min. The spherulite pattern observed by a polarized optical microscope suggested the growth of PEG crystalline lamellae. Crystallization of PEG in MMAx was more restrained than in MACx. From these results, we have concluded that the crystallization behavior of the grafted side chains is strongly influenced by the glass transition of a homogeneously molten sample as well as dilution of the crystallizable chains. Domain spacings for isothermally crystallized graft copolymers were described by interdigitating chain packing in crystalline-amorphous lamellar structure.

Microphase separation in copolymers of hydrophilic PEG blocks and hydrophobic tyrosine-derived segments using simultaneous SAXS/WAXS/DSC

“…But the PEG segments did not recrystallize during cooling in any of our polymers (Figure 4), even when cooled at 1 °C/min; the PEG blocks in polymers such as 15 and 30% PEG 1k DTE and 30%PEG 1k I 2 DTE should have crystallized during cooling at ~ 20 °C below T m as observed in other copolymers [7]. PEG blocks did crystallize when the samples were aged (~ 3 days).…”

“…The influence of PEG depends on whether the polymer is a blend [5–6], a graft [1, 7], a diblock [8–10] or a segmented block [11] copolymer. Segmented block copolymers with PEG as one the blocks have been studied in aqueous solution [12–14], gel [15], and in the solid phase [10, 16–17].…”

Side‐chain crystallization behavior of graft copolymers consisting of an amorphous main chain and crystalline side chains. II. Poly(n‐hexyl methacrylate)‐graft‐poly(ethylene glycol)

“…For graft copolymers, despite their potential importance in industry, only limited studies on the phase behavior and morphology have been reported 2, 5–14. We can expect that in semicrystalline graft copolymers containing crystallizable block chains, the morphology by microphase separation in the molten state before crystallization will be an important factor influencing the crystallization behavior, as reported for semicrystalline diblock copolymers.…”

“…The phase behavior and microphase separation of multicomponent polymers, such as block copolymers and graft copolymers, have attracted much attention because of their ability to form a self‐assembled ordered structure with a nanometer‐sized periodicity 1–14. Diblock copolymers consisting of two incompatible amorphous polymers have been most widely investigated with experimental and theoretical approaches 1, 3, 4.…”

“…In our previous article,14 the crystallization behavior of graft copolymers consisting of an amorphous main chain and crystalline side chains was investigated. The graft copolymers, poly(methyl methacrylate)‐ graft ‐poly(ethylene glycol) (PMMA‐ g ‐PEG) and poly(methyl acrylate)‐ graft ‐poly(ethylene glycol) (PMAc‐ g ‐PEG), were prepared by the random radical copolymerization of α‐methoxy‐ω‐methacryloyl poly(ethylene glycol) with methyl methacrylate and methyl acrylate, respectively.…”