The Critical Lowest Molecular Weight for PEG to Crystallize in Cross‐Linked Networks

Abstract

Summary: Poly(ethylene glycol) (PEG) networks were synthesized by γ‐irradiation. The crystalline behavior of PEG was investigated by differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD). It was shown that the crystallinity of PEG is dramatically lower in the cross‐linked networks than in pure PEG. When the molecular weight of PEG in the networks decreased to 1 000, it could not crystallize at all. Moreover, we also found that the melting temperature of PEG is greatly affected by the presence of a cross‐linked network.The DSC curves of PEG ($\overline M _{\rm w}$ = 1 500) and the corresponding cross‐linked PEG.imageThe DSC curves of PEG ($\overline M _{\rm w}$ = 1 500) and the corresponding cross‐linked PEG.

Doxycycline hydrogels with reversible disulfide crosslinks for dermal wound healing of mustard injuries

“…The shift of −7.56°C in the melting of 8-arm-PEG-SH when converted to 8-arm-PEG-S-TP confirms the substitution of the TP groups on PEG. These observations were consistent with those reported in the past [29]. Furthermore, XPS analysis was conducted to confirm the number of thiol and nitrogen species present on 8-arm-PEG-S-TP.…”

“…The difference in crystallization behavior of polymer networks from that of linear polymers is well known [29]. The crosslinking of polymer chains result in a reduction of crystallinity.…”

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“…The similar phenomena were also found A c c e p t e d M a n u s c r i p t 9 by Binesh et al [29], Qiao et al [30], and Wu et al [23]. The degree of amorphous region increases as the content of PMMA increases to 90%.…”

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“…Crystallinity has been reported for other PEG-based networks with urethane links. [25][26][27][28] The observed crystallinity dependence on the molar mass in PEG networks has been previously reported, [29][30][31] and can be attributed to the lost of mobility of the PEG chains due to the cross-linking. When the molar mass of PEG is low, the chain is not long enough to fold and to crystallize.…”