Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels exhibit temperature-responsive volume changes near physiological temperature, but their low mechanical strength in the swollen state limits use in structurally demanding biomedical applications. In this study, we systematically investigated poly(NIPAAm-co-acrylamide), P(NIPAAm-co-AAm), hydrogels with varying AAm-to-NIPAAm ratios to explore the compositional trade-offs between thermal responsiveness and mechanical performance. Hydrogels were synthesized under fixed crosslinker and water content conditions, and evaluated through compressive mechanical testing, thermal swelling analysis, and crosslinking density estimation. Our results show that increasing AAm content enhances mechanical strength and stiffness but reduces the magnitude of temperature-induced volumetric shrinkage. An intermediate comonomer formulation demonstrated an optimal balance, maintaining both sufficient mechanical integrity for transdermal microneedle insertion and a reversible volume transition. This study highlights the potential of compositional tuning in hydrogel systems to meet the competing demands of responsiveness and durability in advanced biomedical applications.

Immediate action is required to achieve carbon neutrality within the cement industry. The integration of biochar into cement as a component of reinforced concrete has potential to mitigate carbon emissions in the construction sector by enabling carbon sequestration. In pursuit of eco-friendly practices and improved physical properties of cement composites, this study investigated the properties of wood-based, micron-sized biochar as a non-carbonate raw material, including its chemical composition, morphology, and wettability. The characterization of lignocellulosic micro-biochar and its mechanical impact on cement composites was a focus of this study. Cement was partially replaced with varying weight percentages of micro-biochar (1, 3, and 5 wt%), and the effects were evaluated through compressive strength tests after 7 and 28 d. The results demonstrated that the micro-biochar could sustain strength even when substituted for cement. Notably, after 28 d, the compressive strength of the sample with only cement was 29.6 MPa, while the sample with 3 wt% biochar substitution showed 30.9 MPa, indicating a 4.4% increase. This research contributes to sustainable construction practices by offering a green solution for reducing carbon emissions in the industry.