Stabilization Impact of Nano-particles to Polymeric Hydrogels

• Applicant: Professorin Dr. Regine von Klitzing
• Subject Area: Polymer Materials ; Experimental Condensed Matter Physics ; Synthesis and Properties of Functional Materials
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392208985

• Final Report Year: 2024

Final Report Abstract

The aim of the project was to strengthen the (bio)adhesivity and mechanical stability of hydrogel coatings. These two properties are often counteracting. Therefore, the project addressed the understanding of the relationship between the hydrogel structure, the mechanical behaviour and adhesion properties. To increase the adhesion a mussel-inspired strategy was followed. A catecholic amino acid, i.e. 3,4-dihydroxyphenyl-L-alanine (DOPA) which is in the mussel’s bypass was incorporated into a hydrogel as a polymerizable group (dopamine methacrylamide (DMA)). Due to ease of preparation of coatings and faster response to outer stimuli we prepared coatings of microgels instead of macrogels. First, thermo-sensitive P(NIPAM-co-DMA) microgels were synthesized. Since DMA acts also as scavenger, the task was to identify the suitable point of time to add DMA and the total reaction time. Mass spectroscopy, NMR and UV-Vis measurements showed that an addition of DMA 10-15 min after the start of polymerisation and a total reaction time of 60 min are suitable synthesis parameter. DLS measurements showed that the addition of DMA leads to a decrease in volume phase transition temperature (VPTT), strong sharpening of the volume phase transition and a decrease in swelling ability. This is due to cohesive effects induced by the catechol groups. This also leads to a pronounced stiffening of the microgels, as AFM indentation experiments showed. We could show that different indenter sizes between 10 nm and 6700 nm do not detect different elastic moduli. In addition, the adhesive properties could be enhanced by the incorporation of DMA up to 10 mol% of DMA. Higher DMA amount leads to a decrease in adhesion due to pronounced cohesion between the DMA groups. Recent measurements of friction forces of droplets of microgel dispersion being pulled over a substrate indicate a strong increase in friction forces with increasing amount of DMA in the microgels. To summarize, we conclude that the catechol groups within the microgels are responsible for the strengthened mechanics due to enhanced cohesion and the catechol groups in the outer shell of the microgels lead to enhanced adhesive properties. We can fabricate adhesive, mechanical robust and transparent coatings in a controllable manner. The results on P(NIPAM-co-DMA) microgels were presented in peer-reviewed publications and at national and international conferences.

Publications

• Odd‐even effect during layer‐by‐layer assembly of polyelectrolytes inspired by marine mussel. Journal of Polymer Science Part B: Polymer Physics, 55(3), 245-255.
  Wang, Weina; Xu, Yisheng; Han, Haoya; Micciulla, Samantha; Backes, Sebastian; Li, Ang; Xu, Jun; Shen, Weihua; von Klitzing, Regine & Guo, Xuhong
  
• Characterization of hollow silica–polyelectrolyte composite nanoparticles by small-angle X-ray scattering. Journal of Materials Science, 53(5), 3210-3224.
  Han, Haoya; Li, Li; Yang, Qingsong; Tian, Yuchuan; Wang, Yunwei; Ye, Zhishuang; von Klitzing, Regine & Guo, Xuhong
  
• Core–Shell–Corona Silica Hybrid Nanoparticles Templated by Spherical Polyelectrolyte Brushes: A Study by Small Angle X-ray Scattering. Langmuir, 33(38), 9857-9865.
  Han, Haoya; Li, Li; Wang, Weihua; Tian, Yuchuan; Wang, Yunwei; Wang, Junyou; von Klitzing, Regine & Guo, Xuhong
  
• Spherical polyelectrolyte nanogels as templates to prepare hollow silica nanocarriers: observation by small angle X-ray scattering and TEM. RSC Adv., 7(76), 47877-47885.
  Han, Haoya; Li, Li; Tian, Yuchuan; Wang, Yunwei; Ye, Zhishuang; Yang, Qingsong; Wang, Yiming; von Klitzing, Regine & Guo, Xuhong
  
• Mineral-Enhanced Polyacrylic Acid Hydrogel as an Oyster-Inspired Organic–Inorganic Hybrid Adhesive. ACS Applied Materials & Interfaces, 10(12), 10471-10479.
  Li, Ang; Jia, Yunfei; Sun, Shengtong; Xu, Yisheng; Minsky, Burcu Baykal; Stuart, M. A. Cohen; Cölfen, Helmut; von Klitzing, Regine & Guo, Xuhong
  
• Interaction among Spherical Polyelectrolyte Brushes in Concentrated Aqueous Solution. Langmuir, 36(12), 3104-3110.
  Wang, Yunwei; Li, Li; Wang, Yiming; Yang, Qingshong; Ye, Zhishuang; Hua, Chen; Tian, Yuchuan; Klitzing, Regine von & Guo, Xuhong
  
• Selective uptake of different proteins by annealed and quenched cationic spherical polyelectrolyte brushes. Journal of Polymer Science, 58(21), 3018-3030.
  Ye, Zhishuang; Li, Li; Dai, Liheng; Wang, Yunwei; Yang, Qingsong; von Klitzing, Regine & Guo, Xuhong
  
• Copolymerization Kinetics of Dopamine Methacrylamide during PNIPAM Microgel Synthesis for Increased Adhesive Properties. Langmuir, 38(17), 5275-5285.
  Forg, Sandra; Karbacher, Alexandra; Ye, Zhishuang; Guo, Xuhong & von, Klitzing Regine
  
• Influence of Dopamine Methacrylamide on Swelling Behavior and Nanomechanical Properties of PNIPAM Microgels. ACS Applied Materials & Interfaces, 16(1), 1521-1534.
  Forg, Sandra; Guo, Xuhong & von, Klitzing Regine