PEGylated Polyurea Bearing Hindered Urea Bond for Drug Delivery

Chen, Meishan; Xu, Weiguo; Wang, Yanqiao; Yang, Yulin; Jiang, Zhong‐Xing; Ding, Jianxun

doi:10.3390/molecules24081538

Cited by 10 publications

(8 citation statements)

References 24 publications

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“…Contrary to common expectations, these networks show very slow stress relaxation at the processing T , revealing the importance of pressure or compressive stress on the processability of this HUB dynamic polymer network. Despite its dissociative nature, at 130–160 °C, the network exhibited an Arrhenius T -dependence of average stress relaxation time, which is characteristic of vitrimers as well as CANs with dissociative dynamic character. ,, These results agree with findings on other dissociative network systems. , As shown here, the utility of HUB chemistry in the development of reprocessable networks can be extended beyond polyureas and poly(urethane-ureas) to include addition-type networks made from vinyl monomers or polymers. Future efforts will aim to develop other HUB-based cross-linkers with various bulkiness to be used in synthesizing addition-type CANs for a range of applications.…”

supporting

confidence: 85%

“…4,40,54 These results agree with findings on other dissociative network systems. 20,39 As shown here, the utility of HUB chemistry in the development of reprocessable networks can be extended beyond polyureas and poly(urethane-ureas) to include addition-type networks made from vinyl monomers or polymers. Future efforts will aim to develop other HUB-based cross-linkers with various bulkiness to be used in synthesizing addition-type CANs for a range of applications.…”

mentioning

confidence: 94%

“…Unfortunately, polyureas cannot be recycled because of the high stability of the amide bonds in ureas as a result of conjugation effects between the lone electron pair on the nitrogen atom and the π-electrons on the carbonyl p-orbital. , However, incorporating bulky substituents on the amide nitrogen atom can weaken the amide bond by disturbing its orbital coplanarity, which reduces the conjugation effect and weakens the carbonyl–amine interaction, enabling the reversible amidolysis of amide bonds under mild conditions. , Cheng and co-workers studied the effect of steric hindrance on the reaction dynamics of hindered urea bonds (HUBs) and noted that urea bonds with bulky side groups on the nitrogen atom can reversibly dissociate into isocyanates and amines at mild temperature ( T ) . They synthesized HUB-containing polyureas and poly(urethane-urea) materials and demonstrated bulk reprocessability and self-healing at 37 and 100 °C, respectively. , Others have reported on HUB-based polyureas and poly(urea-urethane) networks. − …”

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confidence: 99%

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Reprocessable and Recyclable Chain-Growth Polymer Networks Based on Dynamic Hindered Urea Bonds

Rusayyis

Torkelson

2022

ACS Macro Lett.

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Conventional cross-linked polymers cannot be reprocessed because of the presence of permanent covalent cross-links, preventing reuse and recycling. Covalent adaptable networks (CANs) employ dynamic covalent bonds that undergo dynamic reactions under external stimulus, allowing recyclability of these network materials. Hindered urea chemistry is one of the recently discovered dissociative dynamic chemistries. While hindered urea bonds have traditionally been exploited in the synthesis of step-growth type CANs, the use of hindered urea bonds in the synthesis of chain-growth-type dynamic networks has only been narrowly explored. Here, we present a simple, catalyst-free, fast method to synthesize a hindered-urea-based dynamic cross-linker that can undergo a free radical polymerization with vinyl-type monomers or polymers to form reprocessable CANs. Using this cross-linker, we developed dynamic polymethacrylate networks that can be (re)processed at 80 °C. These dynamic covalent networks exhibit full recovery of cross-link density after multiple recycling steps; they are only the second chain-growth network synthesized directly and exclusively from carbon–carbon double bond monomers to demonstrate such recovery. Unlike other dissociative dynamic polymer networks, polymethacrylate networks that contain dissociative dynamic hindered urea bonds do not flow and maintain their network structure even at high temperature (300 °C). Despite its relatively fast reprocessability, the network showed delayed and extremely slow stress relaxation at the processing temperature. This work offers a simple approach to obtain reprocessable addition-type networks based on hindered urea bonds while revealing the limitations of stress relaxation experiments in relationship to the processability of some dynamic polymer networks.

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confidence: 85%

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confidence: 94%

mentioning

confidence: 99%

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Reprocessable and Recyclable Chain-Growth Polymer Networks Based on Dynamic Hindered Urea Bonds

Rusayyis

Torkelson

2022

ACS Macro Lett.

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“…Polyureas are versatile and robust materials that find application in coatings, 1 adhesives, 2 drug delivery systems, 3 elastomers, 4 and composites. 5 Much of the durability of these materials can be traced to the strong hydrogen bonding stemming from the urea linkage and the linkage's resistance to hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

Isocyanate‐free synthesis of ureas and polyureas via ruthenium catalyzed dehydrogenation of amines and formamides

Langsted

Paulson

Bomann

et al. 2021

J of Applied Polymer Sci

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Ethyl formate is very effective for the formylation of amines and diamines to yield formamides and diformamides, respectively. Subsequent dehydrogenation of 1:1 mixtures of formamides and amines or diformamides and diamines with ruthenium pincer catalysts furnishes ureas and polyureas, respectively. This approach provides access to a large structural variety of ureas and polyureas because a wide range of primary amines and diamines are readily converted to the corresponding ureas and polyureas. Small molecule ureas were isolated in yields of up to 95%, whereas polyureas were isolated in lower yields (up to 68%) due to strong adhesion to the reaction flask and poor solubility impeding product removal. Furthermore, the ease with which hydrogen can be removed from the reaction medium enables the synthesis of polyureas with molecular weights that are among the highest reported to date (M n up to 31,100 g mol À1 ). Notably, this synthetic approach does not necessitate high pressure conditions, simplifying equipment needed for their preparation, and it avoids the use of isocyanates, which have significant health concerns.

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“…Six original research articles focus on the synthesis and characterization of advanced functional polymers. Chen et al synthesized an amphiphilic polyurea consisting of cyclohexyl- tert -butyl polyurea and poly(ethylene glycol) (PEG) for the encapsulation of chemotherapeutic drug paclitaxel (PTX) [11]. The PEGylated polyurea micelle showed more efficient delivery of PTX into 4T1 cells, with enhanced antitumor efficacy.…”

mentioning

confidence: 99%