Tuning Ligand Concentration in Cu(0)-RDRP: A Simple Approach to Control Polymer Dispersity

Cu­(0)-reversible deactivation radical polymerization (RDRP) is a versatile polymerization tool, providing rapid access to well-defined polymers while utilizing mild reaction conditions and low catalyst loadings. However, thus far, this method has not been applied to tailor dispersity, a key parameter that determines the physical properties and applications of polymeric materials. Here, we report a simple to perform method, whereby Cu(0)-RDRP can systematically control polymer dispersity (Đ = 1.07–1.72), while maintaining monomodal molecular weight distributions. By varying the ligand concentration, we could effectively regulate the rates of initiation and deactivation, resulting in polymers of various dispersities. Importantly, both low and high dispersity PMA possess high end-group fidelity, as evidenced by MALDI-ToF-MS, allowing for a range of block copolymers to be prepared with different dispersity configurations. The scope of our method can also be extended to include inexpensive ligands (i.e., PMDETA), which also facilitated the polymerization of lower propagation rate constant monomers (i.e., styrene) and the in situ synthesis of block copolymers. This work significantly expands the toolbox of RDRP methods for tailoring dispersity in polymeric materials

Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers

Controlled polymerization methods are well-established synthetic protocols for the design and preparation of polymeric materials with a high degree of precision over molar mass and architecture. Exciting recent work has shown that the high end-group fidelity and/or functionality inherent in these techniques can enable new routes to depolymerization under relatively mild conditions. Converting polymers back to pure monomers by depolymerization is a potential solution to the environmental and ecological concerns associated with the ultimate fate of polymers. This perspective focuses on the emerging field of depolymerization from polymers synthesized by controlled polymerizations including radical, ionic, and metathesis polymerizations. We provide a critical review of current literature categorized according to polymerization technique and explore numerous concepts and ideas which could be implemented to further enhance depolymerization including lower temperature systems, catalytic depolymerization, increasing polymer scope, and controlled depolymerization

Ubiquitous Nature of Rate Retardation in Reversible Addition–Fragmentation Chain Transfer Polymerization

Reversible addition–fragmentation chain transfer (RAFT) polymerization is one of the most powerful reversible deactivation radical polymerization (RDRP) processes. Rate retardation is prevalent in RAFT and occurs when polymerization rates deviate from ideal conventional radical polymerization kinetics. Herein, we explore beyond what was initially thought to be the culprit of rate retardation: dithiobenzoate chain transfer agents (CTA) with more active monomers (MAMs). Remarkably, polymerizations showed that rate retardation occurs in systems encompassing the use of trithiocarbonates and xanthates CTAs with varying monomeric activities. Both the simple slow fragmentation and intermediate radical termination models show that retardation of all these systems can be described by using a single relationship for a variety of monomer reactivity and CTAs, suggesting rate retardation is a universal phenomenon of varying severity, independent of CTA composition and monomeric activity level

Machine learning-assisted exploration of a versatile polymer platform with charge transfer-dependent full-color emission

No description supplied</p

Efficient Binding, Protection, and Self-Release of dsRNA in Soil by Linear and Star Cationic Polymers

Double stranded RNA (dsRNA) exhibits severe degradation within 3 days in live soil, limiting its potential application in crop protection. Herein we report the efficient binding, protection, and self-release of dsRNA in live soil through the usage of a cationic polymer. Soil stability assays show that linear poly­(2-(dimethylamino)­ethyl acrylate) can delay the degradation of dsRNA by up to 1 week while the star shaped analogue showed an increased stabilization of dsRNA by up to 3 weeks. Thus, the architecture of the polymer can significantly affect the lifetime of dsRNA in soil. In addition, the hydrolysis and dsRNA binding and release profiles of these polymers were carefully evaluated and discussed. Importantly, hydrolysis could occur independently of environmental conditions (e.g., different pH, different temperature) showing the potential for many opportunities in agrochemicals where protection and subsequent self-release of dsRNA in live soil is required

Annual cost of implementing CCDS.

a<p>Assuming the 12 sets of tablets, printers and chargers need replacing every 3 years; and converted to annualised capital charges using annual discount rate of 3.5%.</p><p>Annual cost of implementing CCDS.</p

Hierarchy of harms.

<p>Hierarchy of harms.</p

Secondary outcomes at one month patients by treatment available and received.

a<p>Comparison of groups uses group B as the reference, reflects the variable under consideration:</p><p>Odds Ratio (OR) for logistic regression models for binary variables; and Additive Group Effect (Δ, in same units as dependent variable) for linear models for continuous variables.</p><p>Secondary outcomes at one month patients by treatment available and received.</p

Cost of implementing CCDS by one month.

<p>Cost of implementing CCDS by one month.</p

Characteristics of participants recruited to Intervention and Control groups.

<p>Characteristics of participants recruited to Intervention and Control groups.</p