Dear Colleagues,

This Special Issue is dedicated to developing new functional hydrogels with unique properties, original designs and a hierarchical structure.

Hydrogels, composed of a three-dimensional, cross-linked polymer network and an abundance of water, are representative soft and wet materials. The soft and wet nature of hydrogels has already allowed them to find broad applications in various fields, such as tissue engineering, drug delivery, soft actuators, and flexible electronics. However, conventional hydrogels are mechanically brittle and weak, which severely limits their scope of applications. In the past two decades, a significant volume of research has reported the successful preparation of mechanically strong and tough hydrogels via the design of structures with sacrificial bonds; that is, the sacrificial bonds can break preferentially during deformation to dissipate energy, endowing the material with high toughness. Led by these pioneering studies, attempts have been further made to construct novel structures in hydrogels, and subsequently, various hydrogels with special properties (e.g., anti-fracture, self-healing, adhesive, anti-fatigue, and anti-freezing) have gradually emerged, thus greatly enriching the application prospects of hydrogels.

The properties of hydrogels are highly dependent on their structures. Interestingly, functional hydrogels usually possess exquisite hierarchical structures at different scales, for example, at the nano-, micro-, meso-, and macro-scale. Understanding the structure–property relationship in hydrogels is vital for their functions and applications. Hence, within this topic, we aim to share state-of-the-art advances in the development of functional hydrogels with excellent properties with a hierarchically structural design and expect to provide a powerful paradigm for developing novel functional hydrogels. We sincerely welcome submissions in this exciting field and look forward to presenting these new works.

Dr. Chengtao Yu
Dr. Xiaohua Chang
Dr. Yong Zheng
Prof. Dr. Jian Hu
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Gels is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• functional hydrogels
• hierarchical structure
• multiscale structure
• structure–property relationship
• mechanical property