ABSTRACT
Polyvinyl polymers bearing pendant hole transport functionalities have been extensively explored for solution-processed hole transport layer (HTL) technologies, yet there are only rare examples of high anisotropic packing of the HT moieties of these polymers into substrate-parallel orientations within HTL films. For small molecules, substrate-parallel alignment of HT moieties is a well-established approach to improve overall device performance. To address the longstanding challenge of extension from vapor-deposited small molecules to solution-processable polymer systems, a fundamental chemistry tactic is reported here, involving the positioning of HT side chains within macromolecular frameworks by the construction of HT polymers having bottlebrush topologies. Applying state-of-the-art polymer synthetic techniques, various functional subunits, including triphenylamine (TPA) for hole transport and adhesion to the substrate, and perfluoro alkyl-substituted benzyloxy styrene for migration to the air interface, were organized with exquisite control over the composition and placement throughout the bottlebrush topology. Upon assembling the HT bottlebrush (HTB) polymers into monolayered HTL films on various substrates through spin-casting and thermal annealing, the backbones of HTBs were vertically aligned while the grafts with pendant TPAs were extended parallel to the substrate. The overall design realized high TPA π-stacking along the out-of-plane direction of the substrate in the HTLs, which doubled the efficiency of organic light-emitting diodes compared with linear poly(vinyl triphenylamine)s.
ABSTRACT
Substance use and mental ill health constitute a major public health burden, and a key global policy priority is to reduce illicit and other harmful substance use. Amphetamine-type stimulants (ATS) are the second most used class of illicit drugs and a range of mental health issues have been documented amongst users. This paper explores the relationship between mental health and ATS use, through a thematic analysis of qualitative interviews with n = 18 current and former ATS users in England. The findings are presented by trajectory point of; (1) Initiation of ATS use; (2) continued and increased ATS use and (3) decreased and remitted ATS use. This work helps to develop understanding around the complex and bi-directional relationship between ATS use and mental health. Many ATS users lead chaotic lives and engage in multiple risk behaviours, however there is a need to better understand and conceptualise the dynamic interaction between different individual, social, environment and cultural factors that determine individuals' mental health and substance use. There is no 'one size fits all' approach to prevention and treatment, and these findings highlight the need for more joined-up, tailored and holistic approaches to intervention development.
ABSTRACT
Background: alcohol presents risks to the health of older adults at levels that may have been 'safer' earlier in life. Moderate drinking is associated with some health benefits, and can play a positive role in older people's social lives. To support healthy ageing, we must understand older people's views with regards to their drinking. This study aims to synthesise qualitative evidence exploring the perceptions and experiences of alcohol use by adults aged 50 years and over. Methods: a pre-specified search strategy was applied to Medline, PsychINFO, Scopus, Applied Social Sciences Index and Abstracts and Cumulative Index to Nursing and Allied Health Literature databases from starting dates. Grey literature, relevant journals, references and citations of included articles were searched. Two independent reviewers sifted articles and assessed study quality. Principles of thematic analysis were applied to synthesise the findings from included studies. Results: of 2,056 unique articles identified, 25 articles met inclusion criteria. Four themes explained study findings: routines and rituals of older people's drinking; self-image as a responsible drinker; perceptions of alcohol and the ageing body; and older people's access to alcohol. Differences between gender, countries and social patterns are highlighted. Conclusions: older people perceive themselves as controlled and responsible drinkers. They may not recognise risks associated with alcohol, but appreciate its role in sustaining social and leisure activities important to health and well-being in later life. These are important considerations for intervention development. Drinking is routinised across the life course and may be difficult to change in retirement.
