The limits of precision monomer placement in chain growth polymerization

Precise control over the location of monomers in a polymer chain has been described as the ‘Holy Grail’ of polymer synthesis. Controlled chain growth polymerization techniques have brought this goal closer, allowing the preparation of multiblock copolymers with ordered sequences of functional monomers. Such structures have promising applications ranging from medicine to materials engineering. Here we show, however, that the statistical nature of chain growth polymerization places strong limits on the control that can be obtained. We demonstrate that monomer locations are distributed according to surprisingly simple laws related to the Poisson or beta distributions. The degree of control is quantified in terms of the yield of the desired structure and the standard deviation of the appropriate distribution, allowing comparison between different synthetic techniques. This analysis establishes experimental requirements for the design of polymeric chains with controlled sequence of functionalities, which balance precise control of structure with simplicity of synthesis

Effect of scandium triflate on the RAFT copolymerization of methyl acrylate and vinyl acetate controlled by an acid/base “switchable” chain transfer agent

Modulation of the activity of an acid/base switchable dithiocarbamate RAFT agent, cyanomethyl (4-fluorophenyl)(pyridin-4-yl)carbamodithioate, with the Lewis acid scandium triflate (Sc(OTf)3) was investigated to examine the ability to deliver improved control over RAFT copolymerizations involving both more-activated and less-activated monomers—specifically the copolymerization of methyl acrylate (MA) and vinyl acetate (VAc). The introduction of either 0.5 or 1 mol equiv of Sc(OTf)3, with respect to RAFT agent, into a RAFT copolymerization of MA and VAc provides substantially improved control resulting in significantly reduced molar mass dispersities (Đ) (∼1.1–1.3) than achieved in its absence (Đ ∼ 1.3–1.4). Furthermore, similar introduction of Sc(OTf)3 into MA homopolymerization mediated by the same RAFT agent also delivered polymers of very low Đ (∼1.15). Sc(OTf)3 was also found to lower the rate of polymerization and alter the copolymerization reactivity ratios for MA and VAc. Increasing the Lewis acid concentration provides enhanced incorporation of the less active monomer, VAc, into the copolymers ([Sc(OTf)3]/[RAFT] = 0, rMA = 4.04, rVAc = 0.032; [Sc(OTf)3]/[RAFT] = 0.5, rMA = 3.08, rVAc = 0.17; [Sc(OTf)3]/[RAFT] = 1, rMA = 2.68, rVAc = 0.62). Carbon nuclear magnetic resonance (13C NMR) and differential scanning calorimetry (DSC) analysis of preparative samples confirm the enhanced VAc incorporation with increased levels of Sc(OTf)3. Importantly the inclusion of Sc(OTf)3 does not deleteriously affect the thiocarbonylthio end-groups of the RAFT polymers, with high end-group fidelity being observed in all copolymerizations

Update and critical reanalysis of IUPAC benchmark propagation rate coefficient data

The dataset used to generate IUPAC benchmark Arrhenius parameters for propagation rate coefficients in radical polymerization is extended and reanalyzed, taking into account systematic interlaboratory variation

Controlling dispersity in aqueous atom transfer radical polymerization: rapid and quantitative synthesis of one-pot block copolymers

The dispersity of polymers is efficiently controlled in aqueous atom transfer radical polymerization by modulating the reversible dissociation of the bromide ion from the copper deactivator

Designing a primary care pharmacist-led review for people treated with opioids for persistent pain: a multi-method qualitative study.

oai:repository.canterbury.ac.uk:97w90Opioids are frequently prescribed for persistent non-cancer pain despite limited evidence of long-term effectiveness and risk of harm. Evidence-based interventions to address inappropriate opioid prescribing are lacking. To explore perspectives of people living with persistent pain to understand barriers and facilitators in reducing opioids in the context of a pharmacist-led primary care review, and identify review components and features for optimal delivery. Primary care multi-method qualitative study. Adults with experience of persistent pain and taking opioids participated in semi-structured interviews (n=15, 73% female) and an online discussion forum (n=31). The Theoretical Domains Framework (TDF) provided a framework for data collection and thematic analysis, involving deductive analysis to TDF domains, inductive analysis within-domains to generate subthemes, and subtheme comparison to form across-domain overarching themes. The behaviour change technique taxonomy v.1 and motivational behaviour change technique classification system were used to systematically map themes to behaviour change techniques to identify potential review components and delivery features. 32 facilitator and barrier subthemes for patients reducing opioids were identified across 13 TDF domains. These combined into six overarching themes: learning to live with pain, opioid reduction expectations, assuming a medical model, pharmacist-delivered reviews, pharmacist-patient relationship and patient engagement. Subthemes mapped to 21 unique behaviour change techniques, yielding 17 components and five delivery features for the proposed PROMPPT review. This study generated theoretically-informed evidence for design of a practice pharmacist-led PROMPPT review. Future research will test the feasibility and acceptability of the PROMPPT review and pharmacist training. [Abstract copyright: Copyright © 2024, The Authors.

Acceptability of a proposed practice pharmacist-led review for opioid-treated patients with persistent pain: A qualitative study to inform intervention development

Introduction Regular review of patients prescribed opioids for persistent non-cancer pain (PCNP) is recommended but not routinely undertaken. The PROMPPT (Proactive clinical Review of patients taking Opioid Medicines long-term for persistent Pain led by clinical Pharmacists in primary care Teams) research programme aims to develop and test a pharmacist-led pain review (PROMPPT) to reduce inappropriate opioid use for persistent pain in primary care. This study explored the acceptability of the proposed PROMPPT review to inform early intervention development. Methods Interviews (n = 15) and an online discussion forum (n = 31) with patients prescribed opioids for PCNP and interviews with pharmacists (n = 13), explored acceptability of a proposed PROMPPT review. A prototype PROMPPT review was then tested and refined through 3 iterative cycles of in-practice testing (IPT) (n = 3 practices, n = 3 practice pharmacists, n = 13 patients). Drawing on the Theoretical Framework of Acceptability (TFA), a framework was generated (including a priori TFA constructs) allowing for deductive and inductive thematic analysis to identify aspects of prospective and experienced acceptability. Results Patients felt uncertain about practice pharmacists delivering the proposed PROMPPT review leading to development of content for the invitation letter for IPT (introducing the pharmacist and outlining the aim of the review). After IPT, patients felt that pharmacists were suited to the role as they were knowledgeable and qualified. Pharmacists felt that the proposed reviews would be challenging. Although challenges were experienced during delivery of PROMPPT reviews, pharmacists found that they became easier to deliver with time, practise and experience. Recommendations for optimisations after IPT included development of the training to include examples of challenging consultations. Conclusions Uptake of new healthcare interventions is influenced by perceptions of acceptability. Exploring prospective and experienced acceptability at multiple time points during early intervention development, led to mini-optimisations of the prototype PROMPPT review ahead of a non-randomised feasibility study

Designing a primary care pharmacist-led review for people treated with opioids for persistent pain: a multi-method qualitative study

Background Opioids are frequently prescribed for persistent non-cancer pain despite limited evidence of long-term effectiveness and risk of harm. Evidence-based interventions to address inappropriate opioid prescribing are lacking. Aim To explore perspectives of people living with persistent pain to understand barriers and facilitators in reducing opioids in the context of a pharmacist-led primary care review, and identify review components and features for optimal delivery. Design & setting Primary care multi-method qualitative study. Method Adults with experience of persistent pain and taking opioids participated in semi-structured interviews (n=15, 73% female) and an online discussion forum (n=31). The Theoretical Domains Framework (TDF) provided a framework for data collection and thematic analysis, involving deductive analysis to TDF domains, inductive analysis within-domains to generate subthemes, and subtheme comparison to form across-domain overarching themes. The behaviour change technique taxonomy v.1 and motivational behaviour change technique classification system were used to systematically map themes to behaviour change techniques to identify potential review components and delivery features. Results 32 facilitator and barrier subthemes for patients reducing opioids were identified across 13 TDF domains. These combined into six overarching themes: learning to live with pain, opioid reduction expectations, assuming a medical model, pharmacist-delivered reviews, pharmacist-patient relationship and patient engagement. Subthemes mapped to 21 unique behaviour change techniques, yielding 17 components and five delivery features for the proposed PROMPPT review. Conclusion This study generated theoretically-informed evidence for design of a practice pharmacist-led PROMPPT review. Future research will test the feasibility and acceptability of the PROMPPT review and pharmacist training

Acceptability of a proposed practice pharmacist-led review for opioid-treated patients with persistent pain: A qualitative study to inform intervention development

Introduction Regular review of patients prescribed opioids for persistent non-cancer pain (PCNP) is recommended but not routinely undertaken. The PROMPPT (Proactive clinical Review of patients taking Opioid Medicines long-term for persistent Pain led by clinical Pharmacists in primary care Teams) research programme aims to develop and test a pharmacist-led pain review (PROMPPT) to reduce inappropriate opioid use for persistent pain in primary care. This study explored the acceptability of the proposed PROMPPT review to inform early intervention development. Methods Interviews ( n = 15) and an online discussion forum ( n = 31) with patients prescribed opioids for PCNP and interviews with pharmacists ( n = 13), explored acceptability of a proposed PROMPPT review. A prototype PROMPPT review was then tested and refined through 3 iterative cycles of in-practice testing (IPT) ( n = 3 practices, n = 3 practice pharmacists, n = 13 patients). Drawing on the Theoretical Framework of Acceptability (TFA), a framework was generated (including a priori TFA constructs) allowing for deductive and inductive thematic analysis to identify aspects of prospective and experienced acceptability. Results Patients felt uncertain about practice pharmacists delivering the proposed PROMPPT review leading to development of content for the invitation letter for IPT (introducing the pharmacist and outlining the aim of the review). After IPT, patients felt that pharmacists were suited to the role as they were knowledgeable and qualified. Pharmacists felt that the proposed reviews would be challenging. Although challenges were experienced during delivery of PROMPPT reviews, pharmacists found that they became easier to deliver with time, practise and experience. Recommendations for optimisations after IPT included development of the training to include examples of challenging consultations. Conclusions Uptake of new healthcare interventions is influenced by perceptions of acceptability. Exploring prospective and experienced acceptability at multiple time points during early intervention development, led to mini-optimisations of the prototype PROMPPT review ahead of a non-randomised feasibility study