Dear friend Ray Yang

According to a study on **boronic ester-based dynamic covalent bonds**, these bonds are formed between boronic acids and diols and impart excellent self-healing properties to hydrogels, organic gels, elastomers, and plastics depending on the characteristics of the corresponding polymer (Article Synthesis, characterization and properties of chitosan modif...

In your case, you are trying to synthesize a hydrogel by mixing SAC and P(NIPAAm-st-MAAmBO) without chemical crosslinkers. You hope the hydroxyl groups on chitosan could react with benzoxaborole on MAAmBO to form boronate ester bonds. However, you still failed. In your current study, you have let them mix in pH 6、8、10 condition and no one became a hydrogel. Therefore, you have concluded some possible problems including pKa and steric effect but you could not find the practical relationship between these reasons and your materials.

I'm sorry that I couldn't find any information about the specific reaction between SAC and P(NIPAAm-st-MAAmBO) through boronate ester bonds. However, I hope that the information about boronic ester-based dynamic covalent bonds can help you in your research.

I hope this helps! Let me know if you have any other questions.

Source:

Recent progress in self-healing polymers and hydrogels based on .... https://pubs.rsc.org/en/content/articlehtml/2021/ta/d1ta02308j.

Journal of Materials Chemistry A - RSC Publishing. https://pubs.rsc.org/en/content/articlelanding/2021/ta/d1ta02308j.

Boronic acid and diol-containing polymers: how to choose the correct .... https://pubs.rsc.org/en/content/articlelanding/2020/sm/d0sm00178c.

PHYSICOCHEMICAL CHARACTERIZATION OF CHEMICALLY MODIFIED CHITOSAN BY .... https://www.ipen.br/biblioteca/cd/cbpol/2005/PDF/473.pdf.

Comparison of the acylation of chitosan with succinic anhydride in .... https://www.researchgate.net/publication/292338950_Comparison_of_the_acylation_of_chitosan_with_succinic_anhydride_in_aqueous_suspension_and_in_solution.

Synthesis, characterization and properties of chitosan modified with .... https://www.sciencedirect.com/science/article/pii/S0032386105012681.

y_succinic_anhydride.

Synthesis and characterization of octenyl succinic anhydride modified .... https://www.sciencedirect.com/science/article/pii/S0268005X17318167.

The mechanisms of boronate ester formation and fluorescent ... - Nature. https://www.nature.com/articles/s41557-019-0314-x.

Kaushik Shandilya Thank you very much! I will try to figure out the problems from your recommendations.