Cellulosic polymer colloids, polymers and polyelectrolytes

对新兴生物经济的一个重要贡献是在环境友好的过程中将生物质转化为有用的产品。大约5年前，我们有了一个令人着迷的发现。我们发现了一种新型的纳米纤维素(现在称为毛状纳米纤维素，HNC)，与传统的纤维素纳米晶(NC)和纤维素纳米纤维(CNF)有很大的不同。这种新型粒子由棒状胶体核心组成，并含有许多聚合物或聚电解质链(毛发)。HNC颗粒属于聚合物胶体的范畴。它们可以由脱木素的木纤维(纤维素纤维)通过水处理生产，产率约为50%。另外50%由水溶性纤维素衍生品组成。这项研究将涉及HNC的性质和应用，以及水溶性纤维素及其衍生物的性质。我们建议将研究分为7个主题进行组织。在主题1“HNC的特征”中，我们将尝试使用三种不同的技术对毛发进行成像：(I)用纳米金颗粒(AuNP)标记毛发，然后是电子显微镜；(Ii)使用化学修饰的尖端使用原子力显微镜对毛发进行成像；(Iii)使用随机光学重建显微镜(STORM)。主题2涉及由计算机数控系统生产的HNC，以及右手和左手计算机控制系统的液晶特性。主题3讨论修剪后的HNC的聚合。我们已经证明，由于HNC的几乎所有电荷都位于两端的短毛中，所以人们可以将HNC与二胺(通过生物偶联或点击化学)交联，从而导致端到端的聚集。也应该有可能通过混合带正电荷和带负电荷的平截HNC来制造细长的纳米纤维，从而产生两种类型HNC交替的长纤维。主题4和4涉及HNC的阻垢性能和聚合物/HNC复合材料的防污膜，将用计时安培法进行测量。最后，主题6和主题7分别涉及纤维素水溶性聚合物和聚电解质的性质。具体地说，我们建议研究氧化程度(DO)约为1的纤维素C2-C3碳上含有双醛的纤维素衍生物。我们将这些聚合物称为双醛改性纤维素(DAMC)，以区别于DO=2的双醛纤维素(DAC)。我们建议研究DAMC和DAC的性质，如分子质量、醛基多分散性和密度、持久性长度、Flory-Huggins参数(或聚合物-溶剂相互作用参数等)以及它的长期稳定性。将使用的一些技术是GPC(凝胶渗透色谱、静态光散射和渗透压测量)。我们将把可光开关的分子连接到DAMC上，并将聚合链想象成风暴。

An important contribution to the emerging bioeconomy is the conversion of biomass to useful products in environmentally friendly processes. About 5 years ago, we made a fascinating discovery. We discovered a novel type of nanocellulose (now called hairy nanocellulose, HNC), very different from the conventional cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF). The novel particle consists of a rod-shaped colloidal core and contains many polymeric or polyelectrolyte chains (the “hairs”). HNC particles belong to the class of polymer colloids. They can be produced by an aqueous process from delignified wood fibers (cellulose fibers) with a yield of about 50%. The other 50% consists of water-soluble cellulose derivatives. The research proposed here will address properties and applications of HNC and properties of the water soluble cellulosics and derivatives thereof. We propose to organize the research in 7 topics. In topic 1, “Characterization of HNC”, we will attempt imaging the hairs with three different techniques: (i) labeling the hairs with gold nanoparticles (AuNP), followed by TEM; (ii) imaging the hairs by AFM using chemically modified tips; (iii) by Stochastic Optical Reconstruction Microscopy (STORM). Topic 2 deals with HNC produced from CNC, and the liquid crystalline properties of right and left handed CNC. Topic 3 addresses the aggregation of trimmed HNC. We have shown that one can crosslink carboxylated crew cut HNC with a diamine (via bioconjugation or click chemistry), which results in end-to-end aggregation, since almost all the charges of HNC are located in the short hairs at both ends. It should also be possible to make long slender nanofibrils by mixing positively and negatively charged crew cut HNC, resulting in long fibrils in which the two types of HNC alternate. Topics 4 and 4 deal with antiscaling properties of HNC and antifouling membranes of polymer/HNC composites, to be measured by chronoamperometry. Finally topics 6 and 7 deal with the properties of cellulosic water-soluble polymers and polyelectrolyes respectively. Specifically, we propose to study cellulose derivatives with dialdehyde groups on the C2-C3 carbons of cellulose, with a degree of oxidation (DO) of about 1. We refer to these polymers as dialdehyde modified cellulose (DAMC), to distinguish them from dialdehyde cellulose (DAC), for which DO = 2. We propose to study the properties of DAMC and DAC, such as molecular weight, polydispersity in molecular weight and density of aldehyde groups, persistence length, Flory-Huggins - parameter (or polymer-solvent interaction parameter, etc.), as well as its long-time stability. Some of the techniques used will be GPC (gel permeation chromatography, static light scattering and osmotic pressure measurements. We will attach photoswitchable molecules to DAMC and image the polymeric chains with STORM.