Soft porous crystals (SPCs) that exhibit stimuli-responsive dynamic sorption behavior are attracting interest for gas storage/separation applications. However, the design and synthesis of SPCs is challenging. Herein, we report a new type of SPC based on a [2 + 3] imide-based organic cage (NKPOC-1) and find that it exhibits guest-induced breathing behavior. Various gases were found to induce activated NKPOC-1 crystals to reversibly switch from a "closed" nonporous phase (α) to two porous "open" phases (β and γ). The net effect is gate-opening behavior induced by CO 2 and C3 hydrocarbons. Interestingly, NKPOC-1-α selectively adsorbs propyne over propylene and propane under ambient conditions. Thus, NKPOC-1-α has the potential to separate binary and ternary C3 hydrocarbon mixtures, and the performance was subsequently verified by fixed bed column breakthrough experiments. In addition, molecular dynamics calculations and in situ X-ray diffraction experiments indicate that the gate-opening effect is accompanied by reversible structural transformations. The adsorption energies from molecular dynamics simulations aid are consistent with the experimentally observed selective adsorption phenomena. The understanding gained from this study of NKPOC-1 supports the further development of SPCs for applications in gas separation/storage because SPCs do not inherently suffer from the recyclability problems often encountered with rigid materials.
Traditional covalent
organic frameworks (COFs) are prepared via
polymerization based on small molecular monomers. However, the employment
of polymers as building blocks to construct COFs has not been reported
yet. Herein, we create a new concept of polymer covalent organic frameworks
(polyCOFs) formed by linear polymers as structural building blocks,
which inherit the merits from both COFs and linear polymers. PolyCOFs
represent a new category of porous COF materials that demonstrate
good crystallinity and high stability. More importantly, benefiting
from the flexibility and processability of a linear polymer, polyCOFs
can spontaneously form defect-free, flexible, and freestanding membranes
that exhibit excellent mechanical properties and undergo reversible
mechanical transformation upon exposure to various organic vapors.
For the first time, we demonstrated that polyCOF membranes can be
used as artificial muscles to perform various complicated motions
(e.g., lifting objects, doing “sit-ups”) triggered by
vapors. This study bridges the gap between one-dimensional amorphous
linear polymers and crystalline polymer frameworks and paves a new
avenue to prepare stimuli-responsive actuators using porous COF materials.
To support people with dementia to live at home, a key national and international policy driver is to create dementia-friendly communities which draws attention to the importance of a local neighbourhood and living well with dementia. However, there is a lack of evidence about how people with dementia define and interact with their neighbourhood. This longitudinal narrative research aimed to uncover the meaning, construction and place of neighbourhood in the lives of people with dementia and their care partners through a participatory approach. Five couples, where one partner had an early diagnosis of dementia and capacity to consent, participated in the (up to) one-year mixed qualitative method study. During this time-frame, 65 home visits were conducted, resulting in over 57 hours of interview data alongside the development of other artefacts, such as neighbourhood maps, photographs, diaries and field notes. Narrative analysis was applied within and across the data-sets. This led to the emergence of three themes to describe a connected neighbourhood. First, ‘connecting to people’ is about the couples’ connections with family members, friends and neighbours through a sense of belonging, group identification and responsibilities. Second, ‘connecting to places’ shares the couples’ emotional and biographical attachment to places. Third, ‘connecting to resources’ refers to the couples actively seeking support to live independently and to retain neighbourhood connections.
Developing highly efficient and robust biomimetic catalysts is an essential and feasible strategy to overcome the intrinsic drawbacks of natural enzymes. Inspired by the synthetic strategy of covalent organic frameworks,...
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