Photo-Cross-Linked Hydrogel Replication of Small Objects: A Multistep Final Project for Undergraduate Polymer Laboratories

Abstract

We developed a multipart laboratory experiment on the synthesis of freestanding hydrogels for junior to senior undergraduate students. In this experiment series that runs over the course of multiple 3-h lab periods, small everyday objects belonging to the students are reproduced as hydrogels by first creating negative templates in thermally cured poly(dimethylsiloxane) molds (PDMS), followed by simultaneous photopolymerization and cross-linking using N-vinylpyrrolidone and poly(ethylene glycol) diacrylate in the molds. After being cured at room temperature, the molds are bisected and the objects are recovered. Second, the students optimize the synthesis of poly(N-vinylpyrrolidone)/ poly(ethylene glycol) diacrylate (PVPON/PEGDA) hydrogels via UV-induced polymerization in test-batch scale quartered Petri dishes. Next, using the optimized hydrogel synthesis and the molds from part one, PVPON/PEGDA replicas of their objects are obtained by simultaneous photopolymerization and cross-linking in a UV cross-linking device. Finally, students present their results, methodology, and proposals for industrial scaleup to the class. The students are encouraged by steady progress toward their goal of making a freestanding hydrogel replica of their object and applying their knowledge toward developing a reproduceable protocol. They learn to control synthetic parameters including mixing ratios, polymerization time, and UV intensity as well as readjusting their synthesis procedure based on their understanding of structure−property concepts. This experience provides students with an introduction to polymer synthesis and methodologies familiar to both academic research and industry, which builds confidence in their ability to conduct independent research and development.

Reassessing Undergraduate Polymer Chemistry Laboratory Experiments for Virtual Learning Environments

“…Fully virtual, upper-level polymer experiments regarding the synthesis of block copolymers, hydrogels, and polyelectrolytes ,, would also require strategies that more closely approximate an in-person laboratory such as VR experiments and DLE (e.g., Labster, Beyond Labz). Both VR and DLE are more immersive and offer students a greater degree of control over the outcome of the reaction. , However, many of these experiments feature application-specific objectives that equip students with property-directed polymer design fundamentals.…”

“…110 Journal of Chemical Education While the underlying concepts in these experiments can be adapted to a virtual environment using any of the previously discussed approaches, VR and DLE show the most promise for translating more tactile synthesis protocols such as air-free or Schlenk techniques 113,114 for radical polymerizations to a digital forum. Fully virtual, upper-level polymer experiments regarding the synthesis of block copolymers, hydrogels, and polyelectrolytes 119,120,130 would also require strategies that more closely approximate an in-person laboratory such as VR experiments and DLE (e.g., Labster, Beyond Labz). Both VR and DLE are more immersive and offer students a greater degree of control over the outcome of the reaction.…”

A Homogenous, Photocrosslinkable Poly(dimethylsiloxane‐co‐methylvinylsiloxane) Solution in an Acrylate Monomer

“…[1,2] A hydrosilylation reaction arises between the arcrylate or vinyl and hydridosilyl groups in the PDMS main chains under a special catalyst, resulting in the network formation in PDMS followed by the change in PDMS state. [3,4] This change especially furnishes the PDMS materials with such excellent moldability that they have been utilized for molds, [5] nanoimprint stamps, [6,7] microfluidic chips, [8][9][10] actuators, [10][11][12] biomedical devices, [13,14] sensors, [15,16] E-skins, [16,17] and even for 3D inkjet printing materials. [9,[18][19][20][21] But, it is difficult to produce continuously and massively the crosslinked PDMS elastomers.…”

Zooming in on Polymer Chemistry and Designing Synthesis of High Sulfur-Content Polymers for Virtual Undergraduate Laboratory Experiment

“…Designing laboratory experiments on polymers can connect students with real-world applications, spark and promote students’ interests in science, and help students visualize some fundamental concepts in chemistry. , Several in-person lab experiments on synthesis, characterization, analysis, and applications of polymers were previously covered in the Journal of Chemical Education − and recently (2017) published in the Journal of Chemical Education Special Issue on Polymer Concepts across the Curriculum . − Specifically, polymer syntheses using different polymerization techniques such as radical polymerization (e.g., free-radical, controlled/living: ATRP − and RAFT , ), ring-opening polymerization (ROP) ,− and ring-opening metathesis polymerization (ROMP), , and photopolymerization , were modified to design experiments for undergraduate (UG) laboratories; however, they were all designed for in-person experiments. Contrarily, many lab activities were envisioned, designed, and implemented for remote education even before pandemic time, − and several new studies have also been published in 2020, particularly in the Special Issue: Insights Gained While Teaching Chemistry in the Time of COVID-19 . − Despite the breadth of the literature on distance learning, new virtual laboratory experiments incorporating polymers are missing and can be beneficial.…”